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Alice Ryhl
dcb81aeab4 mm: rust: add VmaNew for f_ops->mmap() 
This type will be used when setting up a new vma in an f_ops->mmap() hook.
Using a separate type from VmaRef allows us to have a separate set of
operations that you are only able to use during the mmap() hook.  For
example, the VM_MIXEDMAP flag must not be changed after the initial setup
that happens during the f_ops->mmap() hook.

To avoid setting invalid flag values, the methods for clearing VM_MAYWRITE
and similar involve a check of VM_WRITE, and return an error if VM_WRITE
is set.  Trying to use `try_clear_maywrite` without checking the return
value results in a compilation error because the `Result` type is marked
#[must_use].

For now, there's only a method for VM_MIXEDMAP and not VM_PFNMAP.  When we
add a VM_PFNMAP method, we will need some way to prevent you from setting
both VM_MIXEDMAP and VM_PFNMAP on the same vma.

Link: https://lkml.kernel.org/r/20250408-vma-v16-6-d8b446e885d9@google.com
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Gary Guo <gary@garyguo.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:25 -07:00
Alice Ryhl
114ba9b9e8 mm: rust: add mmput_async support 
Adds an MmWithUserAsync type that uses mmput_async when dropped but is
otherwise identical to MmWithUser.  This has to be done using a separate
type because the thing we are changing is the destructor.

Rust Binder needs this to avoid a certain deadlock.  See commit
9a9ab0d963 ("binder: fix race between mmput() and do_exit()") for
details.  It's also needed in the shrinker to avoid cleaning up the mm in
the shrinker's context.

Link: https://lkml.kernel.org/r/20250408-vma-v16-5-d8b446e885d9@google.com
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jann Horn <jannh@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:24 -07:00
Alice Ryhl
3105f8f391 mm: rust: add lock_vma_under_rcu 
Currently, the binder driver always uses the mmap lock to make changes to
its vma.  Because the mmap lock is global to the process, this can involve
significant contention.  However, the kernel has a feature called per-vma
locks, which can significantly reduce contention.  For example, you can
take a vma lock in parallel with an mmap write lock.  This is important
because contention on the mmap lock has been a long-term recurring
challenge for the Binder driver.

This patch introduces support for using `lock_vma_under_rcu` from Rust. 
The Rust Binder driver will be able to use this to reduce contention on
the mmap lock.

Link: https://lkml.kernel.org/r/20250408-vma-v16-4-d8b446e885d9@google.com
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:24 -07:00
Alice Ryhl
bf3d331bb8 mm: rust: add vm_insert_page 
The vm_insert_page method is only usable on vmas with the VM_MIXEDMAP
flag, so we introduce a new type to keep track of such vmas.

The approach used in this patch assumes that we will not need to encode
many flag combinations in the type.  I don't think we need to encode more
than VM_MIXEDMAP and VM_PFNMAP as things are now.  However, if that
becomes necessary, using generic parameters in a single type would scale
better as the number of flags increases.

Link: https://lkml.kernel.org/r/20250408-vma-v16-3-d8b446e885d9@google.com
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jann Horn <jannh@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:24 -07:00
Alice Ryhl
040f404b73 mm: rust: add vm_area_struct methods that require read access 
This adds a type called VmaRef which is used when referencing a vma that
you have read access to.  Here, read access means that you hold either the
mmap read lock or the vma read lock (or stronger).

Additionally, a vma_lookup method is added to the mmap read guard, which
enables you to obtain a &VmaRef in safe Rust code.

This patch only provides a way to lock the mmap read lock, but a follow-up
patch also provides a way to just lock the vma read lock.

Link: https://lkml.kernel.org/r/20250408-vma-v16-2-d8b446e885d9@google.com
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:24 -07:00
Alice Ryhl
5bb9ed6cdf mm: rust: add abstraction for struct mm_struct 
Patch series "Rust support for mm_struct, vm_area_struct, and mmap", v16.

This updates the vm_area_struct support to use the approach we discussed
at LPC where there are several different Rust wrappers for vm_area_struct
depending on the kind of access you have to the vma.  Each case allows a
different set of operations on the vma.

This includes an MM MAINTAINERS entry as proposed by Lorenzo:
https://lore.kernel.org/all/33e64b12-aa07-4e78-933a-b07c37ff1d84@lucifer.local/


This patch (of 9):

These abstractions allow you to reference a `struct mm_struct` using both
mmgrab and mmget refcounts.  This is done using two Rust types:

* Mm - represents an mm_struct where you don't know anything about the
  value of mm_users.
* MmWithUser - represents an mm_struct where you know at compile time
  that mm_users is non-zero.

This allows us to encode in the type system whether a method requires that
mm_users is non-zero or not.  For instance, you can always call
`mmget_not_zero` but you can only call `mmap_read_lock` when mm_users is
non-zero.

The struct is called Mm to keep consistency with the C side.

The ability to obtain `current->mm` is added later in this series.

The mm module is defined to only exist when CONFIG_MMU is set.  This
avoids various errors due to missing types and functions when CONFIG_MMU
is disabled.  More fine-grained cfgs can be considered in the future.  See
the thread at [1] for more info.

Link: https://lkml.kernel.org/r/20250408-vma-v16-9-d8b446e885d9@google.com
Link: https://lkml.kernel.org/r/20250408-vma-v16-1-d8b446e885d9@google.com
Link: https://lore.kernel.org/all/202503091916.QousmtcY-lkp@intel.com/
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Acked-by: Balbir Singh <balbirs@nvidia.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jann Horn <jannh@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:24 -07:00
Kevin Brodsky
8472cc4503 riscv: mm: call PUD/P4D ctor in special kernel pgtable alloc 
Constructors for PUD/P4D-level pgtables were recently introduced.  They
should be called for all pgtables; make sure they are called for special
kernel mappings created by create_pgd_mapping() too.

While at it also switch to using pagetable_alloc() like in
alloc_{pte,pmd}_late().

Link: https://lkml.kernel.org/r/20250408095222.860601-13-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:23 -07:00
Kevin Brodsky
cb5d2be838 arm64: mm: call PUD/P4D ctor in __create_pgd_mapping() 
Constructors for PUD/P4D-level pgtables were recently introduced.  They
should be called for all pgtables; make sure they are called for special
kernel mappings created by __create_pgd_mapping() too.

Link: https://lkml.kernel.org/r/20250408095222.860601-12-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:23 -07:00
Kevin Brodsky
0e3a16a760 riscv: mm: clarify ctor mm argument in alloc_{pte,pmd}_late 
pagetable_{pte,pmd}_ctor(mm, ptdesc) skip the ptlock initialisation if mm
is &init_mm.  To avoid unnecessary overhead, it is therefore preferable to
pass the actual mm associated to the PTE/PMD.

Unfortunately, this proves challenging for alloc_{pte,pmd}_late() as the
associated mm is not available at the point where they are called - in
fact not even top-level functions like create_pgd_mapping() are passed the
mm.  As a result they both call the ctor with NULL as mm; this is safe but
potentially wasteful.

This is not a new situation, but let's add a couple of comments to clarify
it.

Link: https://lkml.kernel.org/r/20250408095222.860601-11-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:23 -07:00
Kevin Brodsky
5e8eb9aeed arm64: mm: always call PTE/PMD ctor in __create_pgd_mapping() 
TL;DR: always call the PTE/PMD ctor, passing the appropriate mm to skip
ptlock_init() if unneeded.

__create_pgd_mapping() is used for creating different kinds of mappings,
and may allocate page table pages if passed an allocator callback.  There
are currently three such cases:

1. create_pgd_mapping(), which is used to create the EFI mapping
2. arch_add_memory()
3. map_entry_trampoline()

1. uses pgd_pgtable_alloc() as allocator callback, which calls the
PTE/PMD ctor, while 2.  and 3.  use __pgd_pgtable_alloc(), which does not.
The rationale is most likely that pgtables associated with init_mm do not
make use of split page table locks, and it is therefore unnecessary to
initialise them by calling the ctor.  2.  operates on swapper_pg_dir so
the allocated pgtables are clearly associated with init_mm, this is
arguably the case for 3.  too (the trampoline mapping is never modified so
ptlocks are anyway irrelevant).  1.  corresponds to efi_mm so ptlocks need
to be initialised in that case.

We are now moving towards calling the ctor for all page tables, even those
associated with init_mm.  pagetable_{pte,pmd}_ctor() have become aware of
the associated mm so that the ptlock initialisation can be skipped for
init_mm.  This patch therefore amends the allocator callbacks so that the
PTE/PMD ctor are always called, with an appropriate mm pointer to avoid
unnecessary ptlock overhead.

Modifying the prototype of the allocator callbacks to take the mm and
propagating that pointer all the way down would be pretty invasive. 
Instead:

* __pgd_pgtable_alloc() (cases 2.  and 3.  above) is replaced with
  pgd_pgtable_alloc_init_mm(), resulting in the ctors being called with
  &init_mm.  This is the main functional change in this patch; the ptlock
  still isn't initialised, but other ctor actions (e.g. 
  accounting-related) are now carried out for those allocated pgtables.

* pgd_pgtable_alloc() (case 1.  above) is replaced with
  pgd_pgtable_alloc_special_mm(), resulting in the ctors being called with
  NULL as mm.  No functional change here; NULL essentially means "not
  init_mm", and the ptlock is still initialised.

__pgd_pgtable_alloc() is now the common implementation of those two
helpers.  While at it we switch it to using pagetable_alloc() like
standard pgtable allocator functions and remove the comment regarding ctor
calls (ctors are now always expected to be called).

Link: https://lkml.kernel.org/r/20250408095222.860601-10-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:23 -07:00
Kevin Brodsky
c64f46ee13 arm64: mm: use enum to identify pgtable level instead of *_SHIFT 
Commit 90292aca98 ("arm64: mm: use appropriate ctors for page tables")
introduced pgtable ctor calls in pgd_pgtable_alloc().  To identify the
pgtable level and call the appropriate ctor, the *_SHIFT value associated
with the pgtable level is used.  However, those values do not
unambiguously identify a level, because if a given level is folded, the
*_SHIFT value will be equal to that of the upper level (e.g.  PMD_SHIFT ==
PUD_SHIFT if PMD is folded).

As things stand, there is probably not much damaged done by calling the
ctor for a different level, and ARCH_ENABLE_SPLIT_PMD_PTLOCK is only
selected if PMD isn't folded (so we don't needlessly initialise
pmd_ptlock).  Still, this is pretty confusing, and it would get even more
confusing when adding ctor calls for the remaining levels.

Let's simplify all this by using an enum to identify the pgtable level
instead; this way folding becomes irrelevant.  This is inspired by one of
the m68k pgtable allocators (arch/m68k/include/asm/motorola_pgalloc.h).

Link: https://lkml.kernel.org/r/20250408095222.860601-9-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:22 -07:00
Kevin Brodsky
8240d8d3c5 mm: skip ptlock_init() for kernel PMDs 
Split page table locks are not used for pgtables associated to init_mm, at
any level.  pte_alloc_kernel() does not call ptlock_init() as a result. 
There is however no separate alloc/free functions for kernel PMDs, and
pmd_ptlock_init() is called unconditionally.  When ALLOC_SPLIT_PTLOCKS is
true (e.g.  32-bit architectures or if CONFIG_PREEMPT_RT is selected),
this results in unnecessary dynamic memory allocation every time a kernel
PMD is allocated.

Now that pagetable_pmd_ctor() is passed the associated mm, we can easily
remove this overhead by skipping pmd_ptlock_init() if the pgtable is
associated to init_mm.  No special-casing is needed on the dtor path, as
ptlock_free() is already called unconditionally for all levels. 
(ptlock_free() is a no-op unless a ptlock was allocated for the given
PTP.)

Link: https://lkml.kernel.org/r/20250408095222.860601-8-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:22 -07:00
Kevin Brodsky
10a2e444e4 sparc64: mm: call ctor/dtor for kernel PTEs 
The generic implementation of pte_{alloc_one,free}_kernel now calls the
[cd]tor, without initialising the ptlock needlessly as
pagetable_pte_ctor() skips it for init_mm.

Align sparc64 with the generic implementation by ensuring
pagetable_pte_[cd]tor() are called for kernel PTEs.  As a result the
kernel and user alloc/free functions have the same implementation, and
since pgtable_t is defined as pte_t *, we can have both call a common
helper.

Link: https://lkml.kernel.org/r/20250408095222.860601-7-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:22 -07:00
Kevin Brodsky
8e8299bf38 powerpc: mm: call ctor/dtor for kernel PTEs 
The generic implementation of pte_{alloc_one,free}_kernel now calls the
[cd]tor, without initialising the ptlock needlessly as
pagetable_pte_ctor() skips it for init_mm.

On powerpc, all functions related to PTE allocation are implemented by
common helpers, which are passed a boolean to differentiate user from
kernel pgtables.  This patch aligns the powerpc implementation with the
generic one by calling pagetable_pte_[cd]tor() unconditionally in those
helpers.

Link: https://lkml.kernel.org/r/20250408095222.860601-6-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:22 -07:00
Kevin Brodsky
5a392e991d m68k: mm: call ctor/dtor for kernel PTEs 
The generic implementation of pte_{alloc_one,free}_kernel now calls the
[cd]tor.  Align the m68k/ColdFire implementation of those functions by
calling the [cd]tor explicitly.

Link: https://lkml.kernel.org/r/20250408095222.860601-5-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:21 -07:00
Kevin Brodsky
49f5996664 mm: call ctor/dtor for kernel PTEs 
Since [1], constructors/destructors are expected to be called for all page
table pages, at all levels and for both user and kernel pgtables.  There
is however one glaring exception: kernel PTEs are managed via separate
helpers (pte_alloc_kernel/pte_free_kernel), which do not call the [cd]tor,
at least not in the generic implementation.

The most obvious reason for this anomaly is that init_mm is special-cased
not to use split page table locks.  As a result calling ptlock_init() for
PTEs associated with init_mm would be wasteful, potentially resulting in
dynamic memory allocation.  However, pgtable [cd]tors perform other
actions - currently related to accounting/statistics, and potentially more
functionally significant in the future.

Now that pagetable_pte_ctor() is passed the associated mm, we can make it
skip the call to ptlock_init() for init_mm; this allows us to call the
ctor from pte_alloc_one_kernel() too.  This is matched by a call to the
pgtable destructor in pte_free_kernel(); no special-casing is needed on
that path, as ptlock_free() is already called unconditionally. 
(ptlock_free() is a no-op unless a ptlock was allocated for the given
PTP.)

This patch ensures that all architectures that rely on
<asm-generic/pgalloc.h> call the [cd]tor for kernel PTEs. 
pte_free_kernel() cannot be overridden so changing the generic
implementation is sufficient.  pte_alloc_one_kernel() can be overridden
using __HAVE_ARCH_PTE_ALLOC_ONE_KERNEL, and a few architectures implement
it by calling the page allocator directly.  We amend those so that they
call the generic __pte_alloc_one_kernel() instead, if possible, ensuring
that the ctor is called.

A few architectures do not use <asm-generic/pgalloc.h>; those will be
taken care of separately.

[1] https://lore.kernel.org/linux-mm/20250103184415.2744423-1-kevin.brodsky@arm.com/

Link: https://lkml.kernel.org/r/20250408095222.860601-4-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> # s390
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:21 -07:00
Kevin Brodsky
65ccffcee8 x86: pgtable: always use pte_free_kernel() 
Page table pages are normally freed using the appropriate helper for the
given page table level.  On x86, pud_free_pmd_page() and
pmd_free_pte_page() are an exception to the rule: they call free_page()
directly.

Constructor/destructor calls are about to be introduced for kernel PTEs. 
To avoid missing dtor calls in those helpers, free the PTE pages using
pte_free_kernel() instead of free_page().

While at it also use pmd_free() instead of calling pagetable_dtor()
explicitly at the PMD level.

Link: https://lkml.kernel.org/r/20250408095222.860601-3-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:21 -07:00
Kevin Brodsky
d82d3bf411 mm: pass mm down to pagetable_{pte,pmd}_ctor 
Patch series "Always call constructor for kernel page tables", v2.

There has been much confusion around exactly when page table
constructors/destructors (pagetable_*_[cd]tor) are supposed to be called. 
They were initially introduced for user PTEs only (to support split page
table locks), then at the PMD level for the same purpose.  Accounting was
added later on, starting at the PTE level and then moving to higher levels
(PMD, PUD).  Finally, with my earlier series "Account page tables at all
levels" [1], the ctor/dtor is run for all levels, all the way to PGD.

I thought this was the end of the story, and it hopefully is for user
pgtables, but I was wrong for what concerns kernel pgtables.  The current
situation there makes very little sense:

* At the PTE level, the ctor/dtor is not called (at least in the generic
  implementation).  Specific helpers are used for kernel pgtables at this
  level (pte_{alloc,free}_kernel()) and those have never called the
  ctor/dtor, most likely because they were initially irrelevant in the
  kernel case.

* At all other levels, the ctor/dtor is normally called.  This is
  potentially wasteful at the PMD level (more on that later).

This series aims to ensure that the ctor/dtor is always called for kernel
pgtables, as it already is for user pgtables.  Besides consistency, the
main motivation is to guarantee that ctor/dtor hooks are systematically
called; this makes it possible to insert hooks to protect page tables [2],
for instance.  There is however an extra challenge: split locks are not
used for kernel pgtables, and it would therefore be wasteful to initialise
them (ptlock_init()).

It is worth clarifying exactly when split locks are used.  They clearly
are for user pgtables, but as illustrated in commit 61444cde91 ("ARM:
8591/1: mm: use fully constructed struct pages for EFI pgd allocations"),
they also are for special page tables like efi_mm.  The one case where
split locks are definitely unused is pgtables owned by init_mm; this is
consistent with the behaviour of apply_to_pte_range().

The approach chosen in this series is therefore to pass the mm associated
to the pgtables being constructed to pagetable_{pte,pmd}_ctor() (patch 1),
and skip ptlock_init() if mm == &init_mm (patch 3 and 7).  This makes it
possible to call the PTE ctor/dtor from pte_{alloc,free}_kernel() without
unintended consequences (patch 3).  As a result the accounting functions
are now called at all levels for kernel pgtables, and split locks are
never initialised.

In configurations where ptlocks are dynamically allocated (32-bit,
PREEMPT_RT, etc.) and ARCH_ENABLE_SPLIT_PMD_PTLOCK is selected, this
series results in the removal of a kmem_cache allocation for every kernel
PMD.  Additionally, for certain architectures that do not use
<asm-generic/pgalloc.h> such as s390, the same optimisation occurs at the
PTE level.

===

Things get more complicated when it comes to special pgtable allocators
(patch 8-12).  All architectures need such allocators to create initial
kernel pgtables; we are not concerned with those as the ctor cannot be
called so early in the boot sequence.  However, those allocators may also
be used later in the boot sequence or during normal operations.  There are
two main use-cases:

1. Mapping EFI memory: efi_mm (arm, arm64, riscv)
2. arch_add_memory(): init_mm

The ctor is already explicitly run (at the PTE/PMD level) in the first
case, as required for pgtables that are not associated with init_mm. 
However the same allocators may also be used for the second use-case (or
others), and this is where it gets messy.  Patch 1 calls the ctor with
NULL as mm in those situations, as the actual mm isn't available. 
Practically this means that ptlocks will be unconditionally initialised. 
This is fine on arm - create_mapping_late() is only used for the EFI
mapping.  On arm64, __create_pgd_mapping() is also used by
arch_add_memory(); patch 8/9/11 ensure that ctors are called at all levels
with the appropriate mm.  The situation is similar on riscv, but
propagating the mm down to the ctor would require significant refactoring.
Since they are already called unconditionally, this series leaves riscv
no worse off - patch 10 adds comments to clarify the situation.

From a cursory look at other architectures implementing arch_add_memory(),
s390 and x86 may also need a similar treatment to add constructor calls. 
This is to be taken care of in a future version or as a follow-up.

===

The complications in those special pgtable allocators beg the question:
does it really make sense to treat efi_mm and init_mm differently in e.g. 
apply_to_pte_range()?  Maybe what we really need is a way to tell if an mm
corresponds to user memory or not, and never use split locks for non-user
mm's.  Feedback and suggestions welcome!


This patch (of 12):

In preparation for calling constructors for all kernel page tables while
eliding unnecessary ptlock initialisation, let's pass down the associated
mm to the PTE/PMD level ctors.  (These are the two levels where ptlocks
are used.)

In most cases the mm is already around at the point of calling the ctor so
we simply pass it down.  This is however not the case for special page
table allocators:

* arch/arm/mm/mmu.c
* arch/arm64/mm/mmu.c
* arch/riscv/mm/init.c

In those cases, the page tables being allocated are either for standard
kernel memory (init_mm) or special page directories, which may not be
associated to any mm.  For now let's pass NULL as mm; this will be refined
where possible in future patches.

No functional change in this patch.

Link: https://lore.kernel.org/linux-mm/20250103184415.2744423-1-kevin.brodsky@arm.com/ [1]
Link: https://lore.kernel.org/linux-hardening/20250203101839.1223008-1-kevin.brodsky@arm.com/ [2]
Link: https://lkml.kernel.org/r/20250408095222.860601-1-kevin.brodsky@arm.com
Link: https://lkml.kernel.org/r/20250408095222.860601-2-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>	[s390]
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: <x86@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:21 -07:00
Uladzislau Rezki (Sony)
24c76f37ab vmalloc: use for_each_vmap_node() in purge-vmap-area 
Update a __purge_vmap_area_lazy() to use introduced helper.  This is last
place in vmalloc code.  Also this patch introduces an extra function which
is node_to_id() that converts a vmap_node pointer to an index in array.

__purge_vmap_area_lazy() requires that extra function.

Link: https://lkml.kernel.org/r/20250408151549.77937-3-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Christop Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:20 -07:00
Uladzislau Rezki (Sony)
ce906d7679 vmalloc: switch to for_each_vmap_node() helper 
There are places which can be updated easily to use the helper to iterate
over all vmap-nodes.  This is what this patch does.

The aim is to improve readability and simplify the code.

[akpm@linux-foundation.org: fix build warning]
Link: https://lkml.kernel.org/r/20250408151549.77937-2-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Christop Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:20 -07:00
Uladzislau Rezki (Sony)
4318255091 vmalloc: add for_each_vmap_node() helper 
To simplify iteration over vmap-nodes, add the for_each_vmap_node() macro
that iterates over all nodes in a system.  It tends to simplify the code.

Link: https://lkml.kernel.org/r/20250408151549.77937-1-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Christop Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:20 -07:00
Liu Ye
a40b3fa844 fs/proc/page: refactor to reduce code duplication 
kpageflags_read() and kpagecgroup_read() are quite similar to
kpagecount_read().  Refactor common code into a helper function to reduce
code duplication.

Link: https://lkml.kernel.org/r/20250318063226.223284-1-liuyerd@163.com
Signed-off-by: Liu Ye <liuye@kylinos.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Svetly Todorov <svetly.todorov@memverge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:20 -07:00
Przemek Kitszel
4c97a17a25 xarray: make xa_alloc_cyclic() return 0 on all success cases 
Change xa_alloc_cyclic() to return 0 even on wrap-around.  Do the same for
xa_alloc_cyclic_irq() and xa_alloc_cyclic_bh().

This will prevent any future bug of treating return of 1 as an error:
	int ret = xa_alloc_cyclic(...)
	if (ret) // currently mishandles ret==1
		goto failure;

If there will be someone interested in when wrap-around occurs, there is
still __xa_alloc_cyclic() that behaves as before.  For now there is no
such user.

Link: https://lkml.kernel.org/r/20250320102219.8101-1-przemyslaw.kitszel@intel.com
Signed-off-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Link: https://lore.kernel.org/netdev/Z9gUd-5t8b5NX2wE@casper.infradead.org
Cc: Andriy Shevchenko <andriy.shevchenko@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Cc: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:19 -07:00
Anshuman Khandual
dbb9c166a0 arm64/mm: define ptdesc_t 
Define ptdesc_t type which describes the basic page table descriptor
layout on arm64 platform.  Subsequently all level specific pxxval_t
descriptors are derived from ptdesc_t thus establishing a common original
format, which can also be appropriate for page table entries, masks and
protection values etc which are used at all page table levels.

Link: https://lkml.kernel.org/r/20250407053113.746295-4-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Suggested-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:19 -07:00
Anshuman Khandual
08978fc3b0 mm/ptdump: split effective_prot() into level specific callbacks 
Last argument in effective_prot() is u64 assuming pxd_val() returned value
(all page table levels) is 64 bit.  pxd_val() is very platform specific
and its type should not be assumed in generic MM.

Split effective_prot() into individual page table level specific callbacks
which accepts corresponding pxd_t argument instead and then the
subscribing platform (only x86) just derive pxd_val() from the entries as
required and proceed as earlier.

Link: https://lkml.kernel.org/r/20250407053113.746295-3-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:19 -07:00
Anshuman Khandual
e064e7384f mm/ptdump: split note_page() into level specific callbacks 
Patch series "mm/ptdump: Drop assumption that pxd_val() is u64", v2.

Last argument passed down in note_page() is u64 assuming pxd_val()
returned value (all page table levels) is 64 bit - which might not be the
case going ahead when D128 page tables is enabled on arm64 platform. 
Besides pxd_val() is very platform specific and its type should not be
assumed in generic MM.  A similar problem exists for effective_prot(),
although it is restricted to x86 platform.

This series splits note_page() and effective_prot() into individual page
table level specific callbacks which accepts corresponding pxd_t page
table entry as an argument instead and later on all subscribing platforms
could derive pxd_val() from the table entries as required and proceed as
before.

Define ptdesc_t type which describes the basic page table descriptor
layout on arm64 platform.  Subsequently all level specific pxxval_t
descriptors are derived from ptdesc_t thus establishing a common original
format, which can also be appropriate for page table entries, masks and
protection values etc which are used at all page table levels.


This patch (of 3):

Last argument passed down in note_page() is u64 assuming pxd_val()
returned value (all page table levels) is 64 bit - which might not be the
case going ahead when D128 page tables is enabled on arm64 platform. 
Besides pxd_val() is very platform specific and its type should not be
assumed in generic MM.

Split note_page() into individual page table level specific callbacks
which accepts corresponding pxd_t argument instead and then subscribing
platforms just derive pxd_val() from the entries as required and proceed
as earlier.

Also add a note_page_flush() callback for flushing the last page table
page that was being handled earlier via level = -1.

Link: https://lkml.kernel.org/r/20250407053113.746295-1-anshuman.khandual@arm.com
Link: https://lkml.kernel.org/r/20250407053113.746295-2-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:19 -07:00
Li Wang
e487a5d513 selftest/mm: make hugetlb_reparenting_test tolerant to async reparenting 
In cgroup v2, memory and hugetlb usage reparenting is asynchronous.  This
can cause test flakiness when immediately asserting usage after deleting a
child cgroup.  To address this, add a helper function
`assert_with_retry()` that checks usage values with a timeout-based retry.
This improves test stability without relying on fixed sleep delays.

Also bump up the tolerance size to 7MB.

To avoid False Positives:
  ...
  # Assert memory charged correctly for child only use.
  # actual a = 11 MB
  # expected a = 0 MB
  # fail
  # cleanup
  # [FAIL]
  not ok 11 hugetlb_reparenting_test.sh -cgroup-v2 # exit=1
  # 0
  # SUMMARY: PASS=10 SKIP=0 FAIL=1

Link: https://lkml.kernel.org/r/20250407084201.74492-1-liwang@redhat.com
Signed-off-by: Li Wang <liwang@redhat.com>
Tested-by: Donet Tom <donettom@linux.ibm.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Kirill A. Shuemov <kirill.shutemov@linux.intel.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:18 -07:00
Johannes Weiner
ee414bd97b mm: page_alloc: tighten up find_suitable_fallback() 
find_suitable_fallback() is not as efficient as it could be, and somewhat
difficult to follow.

1. should_try_claim_block() is a loop invariant. There is no point in
   checking fallback areas if the caller is interested in claimable
   blocks but the order and the migratetype don't allow for that.

2. __rmqueue_steal() doesn't care about claimability, so it shouldn't
   have to run those tests.

Different callers want different things from this helper:

1. __compact_finished() scans orders up until it finds a claimable block
2. __rmqueue_claim() scans orders down as long as blocks are claimable
3. __rmqueue_steal() doesn't care about claimability at all

Move should_try_claim_block() out of the loop. Only test it for the
two callers who care in the first place. Distinguish "no blocks" from
"order + mt are not claimable" in the return value; __rmqueue_claim()
can stop once order becomes unclaimable, __compact_finished() can keep
advancing until order becomes claimable.

Before:

 Performance counter stats for './run case-lru-file-mmap-read' (5 runs):

	 85,294.85 msec task-clock                       #    5.644 CPUs utilized               ( +-  0.32% )
	    15,968      context-switches                 #  187.209 /sec                        ( +-  3.81% )
	       153      cpu-migrations                   #    1.794 /sec                        ( +-  3.29% )
	   801,808      page-faults                      #    9.400 K/sec                       ( +-  0.10% )
   733,358,331,786      instructions                     #    1.87  insn per cycle              ( +-  0.20% )  (64.94%)
   392,622,904,199      cycles                           #    4.603 GHz                         ( +-  0.31% )  (64.84%)
   148,563,488,531      branches                         #    1.742 G/sec                       ( +-  0.18% )  (63.86%)
       152,143,228      branch-misses                    #    0.10% of all branches             ( +-  1.19% )  (62.82%)

	   15.1128 +- 0.0637 seconds time elapsed  ( +-  0.42% )

After:

 Performance counter stats for './run case-lru-file-mmap-read' (5 runs):

         84,380.21 msec task-clock                       #    5.664 CPUs utilized               ( +-  0.21% )
            16,656      context-switches                 #  197.392 /sec                        ( +-  3.27% )
               151      cpu-migrations                   #    1.790 /sec                        ( +-  3.28% )
           801,703      page-faults                      #    9.501 K/sec                       ( +-  0.09% )
   731,914,183,060      instructions                     #    1.88  insn per cycle              ( +-  0.38% )  (64.90%)
   388,673,535,116      cycles                           #    4.606 GHz                         ( +-  0.24% )  (65.06%)
   148,251,482,143      branches                         #    1.757 G/sec                       ( +-  0.37% )  (63.92%)
       149,766,550      branch-misses                    #    0.10% of all branches             ( +-  1.22% )  (62.88%)

           14.8968 +- 0.0486 seconds time elapsed  ( +-  0.33% )

Link: https://lkml.kernel.org/r/20250407180154.63348-2-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Brendan Jackman <jackmanb@google.com>
Tested-by: Shivank Garg <shivankg@amd.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Carlos Song <carlos.song@nxp.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:18 -07:00
David Hildenbrand
6e3092d788 kernel/events/uprobes: uprobe_write_opcode() rewrite 
uprobe_write_opcode() does some pretty low-level things that really, it
shouldn't be doing: for example, manually breaking COW by allocating
anonymous folios and replacing mapped pages.

Further, it does seem to do some shaky things: for example, writing to
possible COW-shared anonymous pages or zapping anonymous pages that might
be pinned.  We're also not taking care of uffd, uffd-wp, softdirty ... 
although rather corner cases here.  Let's just get it right like ordinary
ptrace writes would.

Let's rewrite the code, leaving COW-breaking to core-MM, triggered by
FOLL_FORCE|FOLL_WRITE (note that the code was already using FOLL_FORCE).

We'll use GUP to lookup/faultin the page and break COW if required.  Then,
we'll walk the page tables using a folio_walk to perform our page
modification atomically by temporarily unmap the PTE + flushing the TLB.

Likely, we could avoid the temporary unmap in case we can just atomically
write the instruction, but that will be a separate project.

Unfortunately, we still have to implement the zapping logic manually,
because we only want to zap in specific circumstances (e.g., page content
identical).

Note that we can now handle large folios (compound pages) and the shared
zeropage just fine, so drop these checks.

Link: https://lkml.kernel.org/r/20250321113713.204682-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <olsajiri@gmail.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Namhyung kim <namhyung@kernel.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: tongtiangen <tongtiangen@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:18 -07:00
David Hildenbrand
8a5577428e kernel/events/uprobes: pass VMA to set_swbp(), set_orig_insn() and uprobe_write_opcode() 
We already have the VMA, no need to look it up using
get_user_page_vma_remote().  We can now switch to get_user_pages_remote().

Link: https://lkml.kernel.org/r/20250321113713.204682-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <olsajiri@gmail.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Namhyung kim <namhyung@kernel.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: tongtiangen <tongtiangen@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:18 -07:00
David Hildenbrand
b56e644665 kernel/events/uprobes: pass VMA instead of MM to remove_breakpoint() 
Patch series "kernel/events/uprobes: uprobe_write_opcode() rewrite", v3.

Currently, uprobe_write_opcode() implements COW-breaking manually, which
is really far from ideal.  Further, there is interest in supporting
uprobes on hugetlb pages [1], and leaving at least the COW-breaking to the
core will make this much easier.

Also, I think the current code doesn't really handle some things properly
(see patch #3) when replacing/zapping pages.

Let's rewrite it, to leave COW-breaking to the fault handler, and handle
registration/unregistration by temporarily unmapping the anonymous page,
modifying it, and mapping it again.  We still have to implement zapping of
anonymous pages ourselves, unfortunately.

We could look into not performing the temporary unmapping if we can
perform the write atomically, which would likely also make adding hugetlb
support a lot easier.  But, limited (e.g., only PMD/PUD) hugetlb support
could be added on top of this with some tweaking.

Note that we now won't have to allocate another anonymous folio when
unregistering (which will be beneficial for hugetlb as well), we can
simply modify the already-mapped one from the registration (if any).  When
registering a uprobe, we'll first trigger a ptrace-like write fault to
break COW, to then modify the already-mapped page.

Briefly sanity tested with perf probes and with the bpf uprobes selftest.


This patch (of 3):

Pass VMA instead of MM to remove_breakpoint() and remove the "MM" argument
from install_breakpoint(), because it can easily be derived from the VMA.

Link: https://lkml.kernel.org/r/20250321113713.204682-1-david@redhat.com
Link: https://lkml.kernel.org/r/20250321113713.204682-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Namhyung kim <namhyung@kernel.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: tongtiangen <tongtiangen@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:17 -07:00
Gavin Shan
79049bb48a mm/debug: fix parameter passed to page_mapcount_is_type() 
As the comments of page_mapcount_is_type() indicate, the parameter passed
to the function should be one more than page->_mapcount.  However,
page->_mapcount is passed to the function by commit 4ffca5a966 ("mm:
support only one page_type per page") where page_type_has_type() is
replaced by page_mapcount_is_type(), but the parameter isn't adjusted.

Fix the parameter for page_mapcount_is_type() to be (page->__mapcount +
1).  Note that the issue doesn't cause any visible impacts due to the
safety gap introduced by PGTY_mapcount_underflow limit.

[akpm@linux-foundation.org: simplify __dump_folio(), per David]
Link: https://lkml.kernel.org/r/20250321120222.1456770-3-gshan@redhat.com
Fixes: 4ffca5a966 ("mm: support only one page_type per page")
Signed-off-by: Gavin Shan <gshan@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: gehao <gehao@kylinos.cn>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:17 -07:00
Gavin Shan
979f3ef0f7 mm: fix parameter passed to page_mapcount_is_type() 
Patch series "Fix parameter passed to page_mapcount_is_type()", v2.

Found by code inspection.  There are two places where the parameter passed
to page_mapcount_is_type() is (page->_mapcount), which is incorrect since
it should be one more than the value, as explained in the comments to
page_mapcount_is_type(): (a) page_has_type() in page-flags.h (b)
__dump_folio() in mm/debug.c

PATCH[1] fixes the parameter for (a)
PATCH[2] fixes the parameter for (b)

Note that the issue doesn't cause any visible impacts due to the safety
gap introduced by PGTY_mapcount_underflow limit.  So the tag 'Cc:
stable@vger.kernel.org' isn't needed.


This patch (of 2):

As the comments of page_mapcount_is_type() indicate, the parameter passed
to the function should be one more than page->_mapcount.  However,
page->_mapcount (equivalent to page->page_type) is passed to the function
by commit 4ffca5a966 ("mm: support only one page_type per page")
page_type_has_type() is replaced by page_mapcount_is_type(), but the
parameter isn't adjusted.

Fix it by replacing page_mapcount_is_type() with page_type_has_type() in
page_has_type().  Note that the issue doesn't cause any visible impacts
due to the safety gap introduced by PGTY_mapcount_underflow limit.

Link: https://lkml.kernel.org/r/20250321120222.1456770-1-gshan@redhat.com
Link: https://lkml.kernel.org/r/20250321120222.1456770-2-gshan@redhat.com
Fixes: 4ffca5a966 ("mm: support only one page_type per page")
Signed-off-by: Gavin Shan <gshan@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: gehao <gehao@kylinos.cn>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:17 -07:00
Andrei Vagin
a9562fd03a selftests/mm: add PAGEMAP_SCAN guard region test 
Add a selftest to verify the PAGEMAP_SCAN ioctl correctly reports guard
regions using the newly introduced PAGE_IS_GUARD flag.

Link: https://lkml.kernel.org/r/20250324065328.107678-4-avagin@google.com
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:17 -07:00
Andrei Vagin
267bee0cd8 tools headers UAPI: sync linux/fs.h with the kernel sources 
Required for a new PAGEMAP_SCAN test to verify guard region reporting.

Link: https://lkml.kernel.org/r/20250324065328.107678-3-avagin@google.com
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:16 -07:00
Andrei Vagin
a516403787 fs/proc: extend the PAGEMAP_SCAN ioctl to report guard regions 
Patch series "fs/proc: extend the PAGEMAP_SCAN ioctl to report guard
regions", v2.

Introduce the PAGE_IS_GUARD flag in the PAGEMAP_SCAN ioctl to expose
information about guard regions.  This allows userspace tools, such as
CRIU, to detect and handle guard regions.

Currently, CRIU utilizes PAGEMAP_SCAN as a more efficient alternative to
parsing /proc/pid/pagemap.  Without this change, guard regions are
incorrectly reported as swap-anon regions, leading CRIU to attempt dumping
them and subsequently failing.

The series includes updates to the documentation and selftests to reflect
the new functionality.


This patch (of 3):

Introduce the PAGE_IS_GUARD flag in the PAGEMAP_SCAN ioctl to expose
information about guard regions.  This allows userspace tools, such as
CRIU, to detect and handle guard regions.

Link: https://lkml.kernel.org/r/20250324065328.107678-1-avagin@google.com
Link: https://lkml.kernel.org/r/20250324065328.107678-2-avagin@google.com
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:16 -07:00
Sergey Senozhatsky
7eeafde0ac zsmalloc: cleanup headers includes 
Remove unused headers includes from zsmalloc and move pagemap.h and
migrate.h includes into zpdesc header.

Link: https://lkml.kernel.org/r/20250325080427.3449359-1-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:16 -07:00
Dmitry V. Levin
bc6fa71195 selftests/ptrace: add a test case for PTRACE_SET_SYSCALL_INFO 
Check whether PTRACE_SET_SYSCALL_INFO semantics implemented in the kernel
matches userspace expectations.

Link: https://lkml.kernel.org/r/20250303112052.GG24170@strace.io
Signed-off-by: Dmitry V. Levin <ldv@strace.io>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexey Gladkov (Intel) <legion@kernel.org>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: anton ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Brian Cain <bcain@quicinc.com>
Cc: Charlie Jenkins <charlie@rivosinc.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Zankel <chris@zankel.net>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Davide Berardi <berardi.dav@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Eugene Syromiatnikov <esyr@redhat.com>
Cc: Eugene Syromyatnikov <evgsyr@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Maciej W. Rozycki <macro@orcam.me.uk>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Renzo Davoi <renzo@cs.unibo.it>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:16 -07:00
Dmitry V. Levin
26bb32768f ptrace: introduce PTRACE_SET_SYSCALL_INFO request 
PTRACE_SET_SYSCALL_INFO is a generic ptrace API that complements
PTRACE_GET_SYSCALL_INFO by letting the ptracer modify details of system
calls the tracee is blocked in.

This API allows ptracers to obtain and modify system call details in a
straightforward and architecture-agnostic way, providing a consistent way
of manipulating the system call number and arguments across architectures.

As in case of PTRACE_GET_SYSCALL_INFO, PTRACE_SET_SYSCALL_INFO also does
not aim to address numerous architecture-specific system call ABI
peculiarities, like differences in the number of system call arguments for
such system calls as pread64 and preadv.

The current implementation supports changing only those bits of system
call information that are used by strace system call tampering, namely,
syscall number, syscall arguments, and syscall return value.

Support of changing additional details returned by
PTRACE_GET_SYSCALL_INFO, such as instruction pointer and stack pointer,
could be added later if needed, by using struct ptrace_syscall_info.flags
to specify the additional details that should be set.  Currently, "flags"
and "reserved" fields of struct ptrace_syscall_info must be initialized
with zeroes; "arch", "instruction_pointer", and "stack_pointer" fields are
currently ignored.

PTRACE_SET_SYSCALL_INFO currently supports only PTRACE_SYSCALL_INFO_ENTRY,
PTRACE_SYSCALL_INFO_EXIT, and PTRACE_SYSCALL_INFO_SECCOMP operations. 
Other operations could be added later if needed.

Ideally, PTRACE_SET_SYSCALL_INFO should have been introduced along with
PTRACE_GET_SYSCALL_INFO, but it didn't happen.  The last straw that
convinced me to implement PTRACE_SET_SYSCALL_INFO was apparent failure to
provide an API of changing the first system call argument on riscv
architecture.

ptrace(2) man page:

long ptrace(enum __ptrace_request request, pid_t pid, void *addr, void *data);
...
PTRACE_SET_SYSCALL_INFO
       Modify information about the system call that caused the stop.
       The "data" argument is a pointer to struct ptrace_syscall_info
       that specifies the system call information to be set.
       The "addr" argument should be set to sizeof(struct ptrace_syscall_info)).

Link: https://lore.kernel.org/all/59505464-c84a-403d-972f-d4b2055eeaac@gmail.com/
Link: https://lkml.kernel.org/r/20250303112044.GF24170@strace.io
Signed-off-by: Dmitry V. Levin <ldv@strace.io>
Reviewed-by: Alexey Gladkov <legion@kernel.org>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Tested-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Eugene Syromiatnikov <esyr@redhat.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: anton ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Brian Cain <bcain@quicinc.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Zankel <chris@zankel.net>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Davide Berardi <berardi.dav@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Eugene Syromyatnikov <evgsyr@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Maciej W. Rozycki <macro@orcam.me.uk>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Renzo Davoi <renzo@cs.unibo.it>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:15 -07:00
Dmitry V. Levin
c354ec9cee ptrace_get_syscall_info: factor out ptrace_get_syscall_info_op 
Move the code that calculates the type of the system call stop out of
ptrace_get_syscall_info() into a separate function
ptrace_get_syscall_info_op() which is going to be used later to implement
PTRACE_SET_SYSCALL_INFO API.

Link: https://lkml.kernel.org/r/20250303112038.GE24170@strace.io
Signed-off-by: Dmitry V. Levin <ldv@strace.io>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexey Gladkov (Intel) <legion@kernel.org>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: anton ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Brian Cain <bcain@quicinc.com>
Cc: Charlie Jenkins <charlie@rivosinc.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Zankel <chris@zankel.net>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Davide Berardi <berardi.dav@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Eugene Syromiatnikov <esyr@redhat.com>
Cc: Eugene Syromyatnikov <evgsyr@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Maciej W. Rozycki <macro@orcam.me.uk>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Renzo Davoi <renzo@cs.unibo.it>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:15 -07:00
Dmitry V. Levin
cc6622730b syscall.h: introduce syscall_set_nr() 
Similar to syscall_set_arguments() that complements
syscall_get_arguments(), introduce syscall_set_nr() that complements
syscall_get_nr().

syscall_set_nr() is going to be needed along with syscall_set_arguments()
on all HAVE_ARCH_TRACEHOOK architectures to implement
PTRACE_SET_SYSCALL_INFO API.

Link: https://lkml.kernel.org/r/20250303112020.GD24170@strace.io
Signed-off-by: Dmitry V. Levin <ldv@strace.io>
Tested-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Acked-by: Helge Deller <deller@gmx.de> # parisc
Reviewed-by: Maciej W. Rozycki <macro@orcam.me.uk> # mips
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexey Gladkov (Intel) <legion@kernel.org>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: anton ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Brian Cain <bcain@quicinc.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Zankel <chris@zankel.net>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Davide Berardi <berardi.dav@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Eugene Syromiatnikov <esyr@redhat.com>
Cc: Eugene Syromyatnikov <evgsyr@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Renzo Davoi <renzo@cs.unibo.it>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:15 -07:00
Dmitry V. Levin
17fc7b8f9b syscall.h: add syscall_set_arguments() 
This function is going to be needed on all HAVE_ARCH_TRACEHOOK
architectures to implement PTRACE_SET_SYSCALL_INFO API.

This partially reverts commit 7962c2eddb ("arch: remove unused function
syscall_set_arguments()") by reusing some of old syscall_set_arguments()
implementations.

[nathan@kernel.org: fix compile time fortify checks]
  Link: https://lkml.kernel.org/r/20250408213131.GA2872426@ax162
Link: https://lkml.kernel.org/r/20250303112009.GC24170@strace.io
Signed-off-by: Dmitry V. Levin <ldv@strace.io>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Acked-by: Helge Deller <deller@gmx.de> # parisc
Reviewed-by: Maciej W. Rozycki <macro@orcam.me.uk>	[mips]
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexey Gladkov (Intel) <legion@kernel.org>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: anton ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Brian Cain <bcain@quicinc.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Zankel <chris@zankel.net>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Davide Berardi <berardi.dav@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Eugene Syromiatnikov <esyr@redhat.com>
Cc: Eugene Syromyatnikov <evgsyr@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Renzo Davoi <renzo@cs.unibo.it>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:15 -07:00
Dmitry V. Levin
87a929ae4f hexagon: add syscall_set_return_value() 
Patch series "ptrace: introduce PTRACE_SET_SYSCALL_INFO API", v7.

PTRACE_SET_SYSCALL_INFO is a generic ptrace API that complements
PTRACE_GET_SYSCALL_INFO by letting the ptracer modify details of system
calls the tracee is blocked in.

This API allows ptracers to obtain and modify system call details in a
straightforward and architecture-agnostic way, providing a consistent way
of manipulating the system call number and arguments across architectures.

As in case of PTRACE_GET_SYSCALL_INFO, PTRACE_SET_SYSCALL_INFO also does
not aim to address numerous architecture-specific system call ABI
peculiarities, like differences in the number of system call arguments for
such system calls as pread64 and preadv.

The current implementation supports changing only those bits of system
call information that are used by strace system call tampering, namely,
syscall number, syscall arguments, and syscall return value.

Support of changing additional details returned by
PTRACE_GET_SYSCALL_INFO, such as instruction pointer and stack pointer,
could be added later if needed, by using struct ptrace_syscall_info.flags
to specify the additional details that should be set.  Currently, "flags"
and "reserved" fields of struct ptrace_syscall_info must be initialized
with zeroes; "arch", "instruction_pointer", and "stack_pointer" fields are
currently ignored.

PTRACE_SET_SYSCALL_INFO currently supports only PTRACE_SYSCALL_INFO_ENTRY,
PTRACE_SYSCALL_INFO_EXIT, and PTRACE_SYSCALL_INFO_SECCOMP operations. 
Other operations could be added later if needed.

Ideally, PTRACE_SET_SYSCALL_INFO should have been introduced along with
PTRACE_GET_SYSCALL_INFO, but it didn't happen.  The last straw that
convinced me to implement PTRACE_SET_SYSCALL_INFO was apparent failure to
provide an API of changing the first system call argument on riscv
architecture [1].

ptrace(2) man page:

long ptrace(enum __ptrace_request request, pid_t pid, void *addr, void *data);
...
PTRACE_SET_SYSCALL_INFO
       Modify information about the system call that caused the stop.
       The "data" argument is a pointer to struct ptrace_syscall_info
       that specifies the system call information to be set.
       The "addr" argument should be set to sizeof(struct ptrace_syscall_info)).


This patch (of 6):

hexagon is the only architecture that provides HAVE_ARCH_TRACEHOOK but
doesn't define syscall_set_return_value().  Since this function is going
to be needed on all HAVE_ARCH_TRACEHOOK architectures to implement
PTRACE_SET_SYSCALL_INFO API, add it on hexagon, too.

Link: https://lore.kernel.org/all/59505464-c84a-403d-972f-d4b2055eeaac@gmail.com/ [1]
Link: https://lkml.kernel.org/r/20250303111953.GB24170@strace.io
Signed-off-by: Dmitry V. Levin <ldv@strace.io>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexey Gladkov (Intel) <legion@kernel.org>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: anton ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Brian Cain <bcain@quicinc.com>
Cc: Charlie Jenkins <charlie@rivosinc.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Zankel <chris@zankel.net>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Davide Berardi <berardi.dav@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Eugene Syromyatnikov <evgsyr@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Maciej W. Rozycki <macro@orcam.me.uk>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Renzo Davoi <renzo@cs.unibo.it>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Eugene Syromiatnikov <esyr@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:14 -07:00
SoumishDas
f4d1c32489 mm: add kernel-doc comment for free_pgd_range() 
Provide kernel-doc for free_pgd_range() so it's easier to understand what
the function does and how it is used.

Link: https://lkml.kernel.org/r/20250325181325.5774-1-soumish.das@gmail.com
Signed-off-by: SoumishDas <soumish.das@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:14 -07:00
Kemeng Shi
ec9827cd28 mm: swap: replace cluster_swap_free_nr() with swap_entries_put_[map/cache]() 
Replace cluster_swap_free_nr() with swap_entries_put_[map/cache]() to
remove repeat code and leverage batch-remove for entries with last flag. 
After removing cluster_swap_free_nr, only functions with "_nr" suffix
could free entries spanning cross clusters.  Add corresponding description
in comment of swap_entries_put_map_nr() as is first function with "_nr"
suffix and have a non-suffix variant function swap_entries_put_map().

Link: https://lkml.kernel.org/r/20250325162528.68385-9-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Kairui Song <kasong@tencent.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:14 -07:00
Kemeng Shi
d4f8000bd6 mm: swap: factor out helper to drop cache of entries within a single cluster 
Factor out helper swap_entries_put_cache() from put_swap_folio() to serve
as a general-purpose routine for dropping cache flag of entries within a
single cluster.

Link: https://lkml.kernel.org/r/20250325162528.68385-8-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Kairui Song <kasong@tencent.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:14 -07:00
Kemeng Shi
4d71d9062d mm: swap: free each cluster individually in swap_entries_put_map_nr() 
1. Factor out general swap_entries_put_map() helper to drop entries
   belonging to one cluster.  If entries are last map, free entries in
   batch, otherwise put entries with cluster lock acquired and released
   only once.

2. Iterate and call swap_entries_put_map() for each cluster in
   swap_entries_put_nr() to leverage batch-remove for last map belonging
   to one cluster and reduce lock acquire/release in fallback case.

3. As swap_entries_put_nr() won't handle SWAP_HSA_CACHE drop, rename
   it to swap_entries_put_map_nr().

4. As we won't drop each entry invidually with swap_entry_put() now,
   do reclaim in free_swap_and_cache_nr() because
   swap_entries_put_map_nr() is general routine to drop reference and the
   relcaim work should only be done in free_swap_and_cache_nr().  Remove
   stale comment accordingly.

Link: https://lkml.kernel.org/r/20250325162528.68385-7-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Kairui Song <kasong@tencent.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:13 -07:00
Kemeng Shi
f2252acf44 mm: swap: drop last SWAP_MAP_SHMEM flag in batch in swap_entries_put_nr() 
The SWAP_MAP_SHMEM indicates last map from shmem.  Therefore we can drop
SWAP_MAP_SHMEM in batch in similar way to drop last ref count in batch.

Link: https://lkml.kernel.org/r/20250325162528.68385-6-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Kairui Song <kasong@tencent.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:13 -07:00
Kemeng Shi
46e0ab2c62 mm: swap: use swap_entries_free() drop last ref count in swap_entries_put_nr() 
Use swap_entries_free() to directly free swap entries when the swap
entries are not cached and referenced, without needing to set swap entries
to set intermediate SWAP_HAS_CACHE state.

Link: https://lkml.kernel.org/r/20250325162528.68385-5-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Kairui Song <kasong@tencent.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:13 -07:00
Kemeng Shi
835b868878 mm: swap: use swap_entries_free() to free swap entry in swap_entry_put_locked() 
In swap_entry_put_locked(), we will set slot to SWAP_HAS_CACHE before
using swap_entries_free() to do actual swap entry freeing.  This introduce
an unnecessary intermediate state.  By using swap_entries_free() in
swap_entry_put_locked(), we can eliminate the need to set slot to
SWAP_HAS_CACHE.  This change would make the behavior of
swap_entry_put_locked() more consistent with other put() operations which
will do actual free work after put last reference.

Link: https://lkml.kernel.org/r/20250325162528.68385-4-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Reviewed-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-11 17:48:13 -07:00