Patch series "xarray: extract __xa_cmpxchg_raw".
This series reduces duplication between __xa_cmpxchg and __xa_insert by
extracting a new function that does not coerce zero entries to null on the
return path.
The new function may be used by the upcoming Rust xarray abstraction in
its reservation API where it is useful to tell the difference between zero
entries and null slots.
This patch (of 2):
Reduce code duplication by extracting a static inline function that
returns its argument if it is non-zero and NULL otherwise.
This changes xas_result to check for errors before checking for zero but
this cannot change the behavior of existing callers:
- __xa_erase: passes the result of xas_store(_, NULL) which cannot fail.
- __xa_store: passes the result of xas_store(_, entry) which may fail.
xas_store calls xas_create when entry is not NULL which returns NULL
on error, which is immediately checked. This should not change
observable behavior.
- __xa_cmpxchg: passes the result of xas_load(_) which might be zero.
This would previously return NULL regardless of the outcome of
xas_store but xas_store cannot fail if xas_load returns zero
because there is no need to allocate memory.
- xa_store_range: same as __xa_erase.
Link: https://lkml.kernel.org/r/20241112-xarray-insert-cmpxchg-v1-0-dc2bdd8c4136@gmail.com
Link: https://lkml.kernel.org/r/20241112-xarray-insert-cmpxchg-v1-1-dc2bdd8c4136@gmail.com
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andreas Hindborg <a.hindborg@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stephen Rothwell reports that I missed fixing up the documentation when
the argument names changed in commit 938df695e9 ("vsprintf: associate
the format state with the format pointer"), resulting in htmldoc
warnings like
lib/vsprintf.c:2760: warning: Function parameter or struct member 'fmt_str' not described in 'vsnprintf'
lib/vsprintf.c:2760: warning: Excess function parameter 'fmt' description in 'vsnprintf'
...
which I didn't notice because the doc build takes longer than the whole
"real" kernel build for me, so I never bother (and judging by the other
warnings, pretty much nobody else does either).
I guess the bigger issues won't be fixed until the doc build is much
faster (narrator: "That isn's in the cards") but at least linux-next
finds the new cases.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: 938df695e9 ("vsprintf: associate the format state with the format pointer")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Change the LONG_MAX in simple_offset_add to 1024, and do latter:
[root@fedora ~]# mkdir /tmp/dir
[root@fedora ~]# for i in {1..1024}; do touch /tmp/dir/$i; done
touch: cannot touch '/tmp/dir/1024': Device or resource busy
[root@fedora ~]# rm /tmp/dir/123
[root@fedora ~]# touch /tmp/dir/1024
[root@fedora ~]# rm /tmp/dir/100
[root@fedora ~]# touch /tmp/dir/1025
touch: cannot touch '/tmp/dir/1025': Device or resource busy
After we delete file 100, actually this is a empty entry, but the latter
create failed unexpected.
mas_alloc_cyclic has two chance to find empty entry. First find the entry
with range range_lo and range_hi, if no empty entry exist, and range_lo >
min, retry find with range min and range_hi. However, the first call
mas_empty_area may mark mas as EBUSY, and the second call for
mas_empty_area will return false directly. Fix this by reload mas before
second call for mas_empty_area.
[Liam.Howlett@Oracle.com: fix mas_alloc_cyclic() second search]
Link: https://lore.kernel.org/all/20241216060600.287B4C4CED0@smtp.kernel.org/
Link: https://lkml.kernel.org/r/20241216190113.1226145-2-Liam.Howlett@oracle.com
Link: https://lkml.kernel.org/r/20241214093005.72284-1-yangerkun@huaweicloud.com
Fixes: 9b6713cc75 ("maple_tree: Add mtree_alloc_cyclic()")
Signed-off-by: Yang Erkun <yangerkun@huawei.com>
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com> says:
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The strange vbin_printf / bstr_printf interface used to save one- and
two-byte printf numerical arguments into their packed format.
That's more than a bit strange since the argument buffer is supposed to
be an array of 'u32' words, and it's also very different from how the
source of the data (varargs) work - which always do the normal integer
type conversions, so 'char' and 'short' are always passed as int-sized
anyway.
This odd packing causes extra code complexity, and it really isn't worth
it, since the space savings are simply not there: it only happens for
formats like '%hd' (short) and '%hhd' (char), which are very rare
indeed.
In fact, the only other user of this interface seems to be the bpf
helper code (bpf_bprintf_prepare()), and Alexei points out that that
case doesn't support those truncated integer formatting options at all
in the first place.
As a result, bpf_bprintf_prepare() doesn't need any changes for this,
and TRACE_BPRINT uses 'vbin_printf()' -> 'bstr_printf()' for the
formatting and hopefully doesn't expose the odd packing any other way
(knock wood).
Link: https://lore.kernel.org/all/CAADnVQJy65oOubjxM-378O3wDfhuwg8TGa9hc-cTv6NmmUSykQ@mail.gmail.com/
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We'll squirrel away the size of the number in 'struct fmt' instead.
We have two fairly separate state structures: the 'decode state' is in
'struct fmt', while the 'printout format' is in 'printf_spec'. Both
structures are small enough to pass around in registers even across
function boundaries (ie two words), even on 32-bit machines.
The goal here is to avoid the case statements on the format states,
which generate either deep conditionals or jump tables, while also
keeping the state size manageable.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make the format_decode() code generation easier to look at by getting
the strange and unlikely cases out of line.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
At some point skip_atoi() had been marked 'noinline_for_stack', but it
turns out that this is now a pessimization, and not inlining it actually
results in a stack frame in format decoding due to the call and thus
hurts stack usage rather than helping.
With the simplistic atoi function inlined, the format decoding now needs
no frame at all.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We did the flags as an array earlier, they had simpler rules. The final
format specifiers are a bit more complex since they have more fields to
deal with, and we want to handle the length modifiers at the same time.
But like the flags, we're better off just making it a data-driven table
rather than some case statement.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Rather than a case statement, just look up the printf format flags
(justification, zero-padding etc) using a small table.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The vsnprintf() code is written as a state machine as it walks the
format pointer, but for various historical reasons the state is oddly
named and was encoded as the 'type' field in the 'struct printf_spec'.
That naming came from the fact that the states used to not just encode
the state of the state machine, but also the various integer types that
would then be printed out.
Let's make the state machine more obvious, and actually call it 'state',
and associate it with the format pointer itself, rather than the
'printf_spec' that contains the currently decoded formatting specs.
This also removes the bit packing from printf_spec, which makes it much
easier on the compiler.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Every single caller wants to know what the next format location is, but
instead the function returned the length of the processed part and so
every single return statement in the format_decode() function was
instead subtracting the start of the format string.
The callers that that did want to know the length (in addition to the
end of the format processing) already had to save off the start of the
format string anyway. So this was all just doing extra processing both
on the caller and callee sides.
Just change the calling convention to return the end of the format
processing, making everything simpler (and preparing for yet more
simplification to come).
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that we have simplified the number format types, the top-level
switch table can easily just handle all the remaining cases, and we
don't need to have a case statement with a conditional on the same
expression as the switch statement.
We do want to fall through to the common 'number()' case, but that's
trivially done by making the other case statements use 'continue'
instead of 'break'. They are just looping back to the top, after all.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Instead of dealing with all the different special types (size_t,
unsigned char, ptrdiff_t..) just deal with the size of the integer type
and the sign.
This avoids a lot of unnecessary case statements, and the games we play
with the value of the 'SIGN' flags value
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Lockdep changes for v6.14:
- Use swap() macro in the ww_mutex test.
- Minor fixes and documentation for lockdep configs on internal data structure sizes.
- Some "-Wunused-function" warning fixes for Clang.
Rust locking changes for v6.14:
- Add Rust locking files into LOCKING PRIMITIVES maintainer entry.
- Add `Lock<(), ..>::from_raw()` function to support abstraction on low level locking.
- Expose `Guard::new()` for public usage and add type alias for spinlock and mutex guards.
- Add lockdep checking when creating a new lock `Guard`.
gf128mul_4k_bbe(), gf128mul_bbe() and gf128mul_init_4k_bbe()
are part of the library originally added in 2006 by
commit c494e0705d ("[CRYPTO] lib: table driven multiplications in
GF(2^128)")
but have never been used.
Remove them.
(BBE is Big endian Byte/Big endian bits
Note the 64k table version is used and I've left that in)
Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Move the hash table growth check and work scheduling outside the
rht lock to prevent a possible circular locking dependency.
The original implementation could trigger a lockdep warning due to
a potential deadlock scenario involving nested locks between
rhashtable bucket, rq lock, and dsq lock. By relocating the
growth check and work scheduling after releasing the rth lock, we break
this potential deadlock chain.
This change expands the flexibility of rhashtable by removing
restrictive locking that previously limited its use in scheduler
and workqueue contexts.
Import to say that this calls rht_grow_above_75(), which reads from
struct rhashtable without holding the lock, if this is a problem, we can
move the check to the lock, and schedule the workqueue after the lock.
Fixes: f0e1a0643a ("sched_ext: Implement BPF extensible scheduler class")
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
Modified so that atomic_inc is also moved outside of the bucket
lock along with the growth above 75% check.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Lockdep has a set of configs used to determine the size of the static
arrays that it uses. However, the upper limit that was initially setup
for these configs is too high (30 bit shift). This equates to several
GiB of static memory for individual symbols. Using such high values
leads to linker errors:
$ make defconfig
$ ./scripts/config -e PROVE_LOCKING --set-val LOCKDEP_BITS 30
$ make olddefconfig all
[...]
ld: kernel image bigger than KERNEL_IMAGE_SIZE
ld: section .bss VMA wraps around address space
Adjust the upper limits to the maximum values that avoid these issues.
The need for anything more, likely points to a problem elsewhere. Note
that LOCKDEP_CHAINS_BITS was intentionally left out as its upper limit
had a different symptom and has already been fixed [1].
Reported-by: J. R. Okajima <hooanon05g@gmail.com>
Closes: https://lore.kernel.org/all/30795.1620913191@jrobl/ [1]
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20241024183631.643450-2-cmllamas@google.com
This is new API which caters to the following requirements:
- Pack or unpack a large number of fields to/from a buffer with a small
code footprint. The current alternative is to open-code a large number
of calls to pack() and unpack(), or to use packing() to reduce that
number to half. But packing() is not const-correct.
- Use unpacked numbers stored in variables smaller than u64. This
reduces the rodata footprint of the stored field arrays.
- Perform error checking at compile time, rather than runtime, and return
void from the API functions. Because the C preprocessor can't generate
variable length code (loops), this is a bit tricky to do with macros.
To handle this, implement macros which sanity check the packed field
definitions based on their size. Finally, a single macro with a chain of
__builtin_choose_expr() is used to select the appropriate macros. We
enforce the use of ascending or descending order to avoid O(N^2) scaling
when checking for overlap. Note that the macros are written with care to
ensure that the compilers can correctly evaluate the resulting code at
compile time. In particular, care was taken with avoiding too many nested
statement expressions. Nested statement expressions trip up some
compilers, especially when passing down variables created in previous
statement expressions.
There are two key design choices intended to keep the overall macro code
size small. First, the definition of each CHECK_PACKED_FIELDS_N macro is
implemented recursively, by calling the N-1 macro. This avoids needing
the code to repeat multiple times.
Second, the CHECK_PACKED_FIELD macro enforces that the fields in the
array are sorted in order. This allows checking for overlap only with
neighboring fields, rather than the general overlap case where each field
would need to be checked against other fields.
The overlap checks use the first two fields to determine the order of the
remaining fields, thus allowing either ascending or descending order.
This enables drivers the flexibility to keep the fields ordered in which
ever order most naturally fits their hardware design and its associated
documentation.
The CHECK_PACKED_FIELDS macro is directly called from within pack_fields
and unpack_fields, ensuring that all drivers using the API receive the
benefits of the compile-time checks. Users do not need to directly call
any of the macros directly.
The CHECK_PACKED_FIELDS and its helper macros CHECK_PACKED_FIELDS_(0..50)
are generated using a simple C program in scripts/gen_packed_field_checks.c
This program can be compiled on demand and executed to generate the
macro code in include/linux/packing.h. This will aid in the event that a
driver needs more than 50 fields. The generator can be updated with a new
size, and used to update the packing.h header file. In practice, the ice
driver will need to support 27 fields, and the sja1105 driver will need
to support 0 fields. This on-demand generation avoids the need to modify
Kbuild. We do not anticipate the maximum number of fields to grow very
often.
- Reduced rodata footprint for the storage of the packed field arrays.
To that end, we have struct packed_field_u8 and packed_field_u16, which
define the fields with the associated type. More can be added as
needed (unlikely for now). On these types, the same generic pack_fields()
and unpack_fields() API can be used, thanks to the new C11 _Generic()
selection feature, which can call pack_fields_u8() or pack_fields_16(),
depending on the type of the "fields" array - a simplistic form of
polymorphism. It is evaluated at compile time which function will actually
be called.
Over time, packing() is expected to be completely replaced either with
pack() or with pack_fields().
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Co-developed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20241210-packing-pack-fields-and-ice-implementation-v10-3-ee56a47479ac@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Most of the sanity checks in pack() and unpack() can be covered at
compile time. There is only one exception, and that is truncation of the
uval during a pack() operation.
We'd like the error-less __pack() to catch that condition as well. But
at the same time, it is currently the responsibility of consumer drivers
(currently just sja1105) to print anything at all when this error
occurs, and then discard the return code.
We can just print a loud warning in the library code and continue with
the truncated __pack() operation. In practice, having the warning is
very important, see commit 24deec6b9e ("net: dsa: sja1105: disallow
C45 transactions on the BASE-TX MDIO bus") where the bug was caught
exactly by noticing this print.
Add the first print to the packing library, and at the same time remove
the print for the same condition from the sja1105 driver, to avoid
double printing.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20241210-packing-pack-fields-and-ice-implementation-v10-2-ee56a47479ac@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Pull locking fixes from Borislav Petkov:
- Remove if_not_guard() as it is generating incorrect code
- Fix the initialization of the fake lockdep_map for the first locked
ww_mutex
* tag 'locking_urgent_for_v6.13_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
headers/cleanup.h: Remove the if_not_guard() facility
locking/ww_mutex: Fix ww_mutex dummy lockdep map selftest warnings
Pull misc fixes from Andrew Morton:
"24 hotfixes. 17 are cc:stable. 15 are MM and 9 are non-MM.
The usual bunch of singletons - please see the relevant changelogs for
details"
* tag 'mm-hotfixes-stable-2024-12-07-22-39' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (24 commits)
iio: magnetometer: yas530: use signed integer type for clamp limits
sched/numa: fix memory leak due to the overwritten vma->numab_state
mm/damon: fix order of arguments in damos_before_apply tracepoint
lib: stackinit: hide never-taken branch from compiler
mm/filemap: don't call folio_test_locked() without a reference in next_uptodate_folio()
scatterlist: fix incorrect func name in kernel-doc
mm: correct typo in MMAP_STATE() macro
mm: respect mmap hint address when aligning for THP
mm: memcg: declare do_memsw_account inline
mm/codetag: swap tags when migrate pages
ocfs2: update seq_file index in ocfs2_dlm_seq_next
stackdepot: fix stack_depot_save_flags() in NMI context
mm: open-code page_folio() in dump_page()
mm: open-code PageTail in folio_flags() and const_folio_flags()
mm: fix vrealloc()'s KASAN poisoning logic
Revert "readahead: properly shorten readahead when falling back to do_page_cache_ra()"
selftests/damon: add _damon_sysfs.py to TEST_FILES
selftest: hugetlb_dio: fix test naming
ocfs2: free inode when ocfs2_get_init_inode() fails
nilfs2: fix potential out-of-bounds memory access in nilfs_find_entry()
...
The never-taken branch leads to an invalid bounds condition, which is by
design. To avoid the unwanted warning from the compiler, hide the
variable from the optimizer.
../lib/stackinit_kunit.c: In function 'do_nothing_u16_zero':
../lib/stackinit_kunit.c:51:49: error: array subscript 1 is outside array bounds of 'u16[0]' {aka 'short unsigned int[]'} [-Werror=array-bounds=]
51 | #define DO_NOTHING_RETURN_SCALAR(ptr) *(ptr)
| ^~~~~~
../lib/stackinit_kunit.c:219:24: note: in expansion of macro 'DO_NOTHING_RETURN_SCALAR'
219 | return DO_NOTHING_RETURN_ ## which(ptr + 1); \
| ^~~~~~~~~~~~~~~~~~
Link: https://lkml.kernel.org/r/20241117113813.work.735-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Current solution to adjust codetag references during page migration is
done in 3 steps:
1. sets the codetag reference of the old page as empty (not pointing
to any codetag);
2. subtracts counters of the new page to compensate for its own
allocation;
3. sets codetag reference of the new page to point to the codetag of
the old page.
This does not work if CONFIG_MEM_ALLOC_PROFILING_DEBUG=n because
set_codetag_empty() becomes NOOP. Instead, let's simply swap codetag
references so that the new page is referencing the old codetag and the old
page is referencing the new codetag. This way accounting stays valid and
the logic makes more sense.
Link: https://lkml.kernel.org/r/20241129025213.34836-1-00107082@163.com
Fixes: e0a955bf7f ("mm/codetag: add pgalloc_tag_copy()")
Signed-off-by: David Wang <00107082@163.com>
Closes: https://lore.kernel.org/lkml/20241124074318.399027-1-00107082@163.com/
Acked-by: Suren Baghdasaryan <surenb@google.com>
Suggested-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Yu Zhao <yuzhao@google.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
