Patch series "mm: allow pte_offset_map[_lock]() to fail", v2.
What is it all about? Some mmap_lock avoidance i.e. latency reduction.
Initially just for the case of collapsing shmem or file pages to THPs; but
likely to be relied upon later in other contexts e.g. freeing of empty
page tables (but that's not work I'm doing). mmap_write_lock avoidance
when collapsing to anon THPs? Perhaps, but again that's not work I've
done: a quick attempt was not as easy as the shmem/file case.
I would much prefer not to have to make these small but wide-ranging
changes for such a niche case; but failed to find another way, and have
heard that shmem MADV_COLLAPSE's usefulness is being limited by that
mmap_write_lock it currently requires.
These changes (though of course not these exact patches) have been in
Google's data centre kernel for three years now: we do rely upon them.
What is this preparatory series about?
The current mmap locking will not be enough to guard against that tricky
transition between pmd entry pointing to page table, and empty pmd entry,
and pmd entry pointing to huge page: pte_offset_map() will have to
validate the pmd entry for itself, returning NULL if no page table is
there. What to do about that varies: sometimes nearby error handling
indicates just to skip it; but in many cases an ACTION_AGAIN or "goto
again" is appropriate (and if that risks an infinite loop, then there must
have been an oops, or pfn 0 mistaken for page table, before).
Given the likely extension to freeing empty page tables, I have not
limited this set of changes to a THP config; and it has been easier, and
sets a better example, if each site is given appropriate handling: even
where deeper study might prove that failure could only happen if the pmd
table were corrupted.
Several of the patches are, or include, cleanup on the way; and by the
end, pmd_trans_unstable() and suchlike are deleted: pte_offset_map() and
pte_offset_map_lock() then handle those original races and more. Most
uses of pte_lockptr() are deprecated, with pte_offset_map_nolock() taking
its place.
This patch (of 32):
Use pmdp_get_lockless() in preference to READ_ONCE(*pmdp), to get a more
reliable result with PAE (or READ_ONCE as before without PAE); and remove
the unnecessary extra barrier()s which got left behind in its callers.
HOWEVER: Note the small print in linux/pgtable.h, where it was designed
specifically for fast GUP, and depends on interrupts being disabled for
its full guarantee: most callers which have been added (here and before)
do NOT have interrupts disabled, so there is still some need for caution.
Link: https://lkml.kernel.org/r/f35279a9-9ac0-de22-d245-591afbfb4dc@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Yu Zhao <yuzhao@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zack Rusin <zackr@vmware.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Commit 71024cb4a0 ("frontswap: remove frontswap_tmem_exclusive_gets")
removed support for exclusive loads from frontswap as it was not used.
Bring back exclusive loads support to frontswap by adding an "exclusive"
output parameter to frontswap_ops->load.
On the zswap side, add a module parameter to enable/disable exclusive
loads, and a config option to control the boot default value. Refactor
zswap entry invalidation in zswap_frontswap_invalidate_page() into
zswap_invalidate_entry() to reuse it in zswap_frontswap_load() if
exclusive loads are enabled.
With exclusive loads, we avoid having two copies of the same page in
memory (compressed & uncompressed) after faulting it in from zswap. On
the other hand, if the page is to be reclaimed again without being
dirtied, it will be re-compressed. Compression is not usually slow, and a
page that was just faulted in is less likely to be reclaimed again soon.
Link: https://lkml.kernel.org/r/20230607195143.1473802-1-yosryahmed@google.com
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Suggested-by: Yu Zhao <yuzhao@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
managed pages has already been set to 0 in free_area_init_core_hotplug(),
via zone_init_internals() on each zone. It's pointless to reset again.
Furthermore, reset_node_managed_pages() no longer needs to be exposed
outside of mm/memblock.c. Remove declaration in include/linux/memblock.h
and define it as static.
In addtion to this, the only caller of reset_node_managed_pages() is
reset_all_zones_managed_pages(), which is annotated with __init, so it
should be safe to also mark reset_node_managed_pages() as __init.
Link: https://lkml.kernel.org/r/20230607024548.1240-1-haifeng.xu@shopee.com
Signed-off-by: Haifeng Xu <haifeng.xu@shopee.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When commit 19343b5bdd ("mm/page-writeback: introduce tracepoint for
wait_on_page_writeback()") repurposed the writeback_dirty_page trace event
as a template to create its new wait_on_page_writeback trace event, it
ended up opening a window to NULL pointer dereference crashes due to the
(infrequent) occurrence of a race where an access to a page in the
swap-cache happens concurrently with the moment this page is being written
to disk and the tracepoint is enabled:
BUG: kernel NULL pointer dereference, address: 0000000000000040
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 800000010ec0a067 P4D 800000010ec0a067 PUD 102353067 PMD 0
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 1 PID: 1320 Comm: shmem-worker Kdump: loaded Not tainted 6.4.0-rc5+ #13
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS edk2-20230301gitf80f052277c8-1.fc37 03/01/2023
RIP: 0010:trace_event_raw_event_writeback_folio_template+0x76/0xf0
Code: 4d 85 e4 74 5c 49 8b 3c 24 e8 06 98 ee ff 48 89 c7 e8 9e 8b ee ff ba 20 00 00 00 48 89 ef 48 89 c6 e8 fe d4 1a 00 49 8b 04 24 <48> 8b 40 40 48 89 43 28 49 8b 45 20 48 89 e7 48 89 43 30 e8 a2 4d
RSP: 0000:ffffaad580b6fb60 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff90e38035c01c RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff90e38035c044
RBP: ffff90e38035c024 R08: 0000000000000002 R09: 0000000000000006
R10: ffff90e38035c02e R11: 0000000000000020 R12: ffff90e380bac000
R13: ffffe3a7456d9200 R14: 0000000000001b81 R15: ffffe3a7456d9200
FS: 00007f2e4e8a15c0(0000) GS:ffff90e3fbc80000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000040 CR3: 00000001150c6003 CR4: 0000000000170ee0
Call Trace:
<TASK>
? __die+0x20/0x70
? page_fault_oops+0x76/0x170
? kernelmode_fixup_or_oops+0x84/0x110
? exc_page_fault+0x65/0x150
? asm_exc_page_fault+0x22/0x30
? trace_event_raw_event_writeback_folio_template+0x76/0xf0
folio_wait_writeback+0x6b/0x80
shmem_swapin_folio+0x24a/0x500
? filemap_get_entry+0xe3/0x140
shmem_get_folio_gfp+0x36e/0x7c0
? find_busiest_group+0x43/0x1a0
shmem_fault+0x76/0x2a0
? __update_load_avg_cfs_rq+0x281/0x2f0
__do_fault+0x33/0x130
do_read_fault+0x118/0x160
do_pte_missing+0x1ed/0x2a0
__handle_mm_fault+0x566/0x630
handle_mm_fault+0x91/0x210
do_user_addr_fault+0x22c/0x740
exc_page_fault+0x65/0x150
asm_exc_page_fault+0x22/0x30
This problem arises from the fact that the repurposed writeback_dirty_page
trace event code was written assuming that every pointer to mapping
(struct address_space) would come from a file-mapped page-cache object,
thus mapping->host would always be populated, and that was a valid case
before commit 19343b5bdd. The swap-cache address space
(swapper_spaces), however, doesn't populate its ->host (struct inode)
pointer, thus leading to the crashes in the corner-case aforementioned.
commit 19343b5bdd ended up breaking the assignment of __entry->name and
__entry->ino for the wait_on_page_writeback tracepoint -- both dependent
on mapping->host carrying a pointer to a valid inode. The assignment of
__entry->name was fixed by commit 68f23b8906 ("memcg: fix a crash in
wb_workfn when a device disappears"), and this commit fixes the remaining
case, for __entry->ino.
Link: https://lkml.kernel.org/r/20230606233613.1290819-1-aquini@redhat.com
Fixes: 19343b5bdd ("mm/page-writeback: introduce tracepoint for wait_on_page_writeback()")
Signed-off-by: Rafael Aquini <aquini@redhat.com>
Reviewed-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Aristeu Rozanski <aris@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Within each nfs_server sysfs tree, add an entry named "shutdown". Writing
1 to this file will set the cl_shutdown bit on the rpc_clnt structs
associated with that mount. If cl_shutdown is set, the task scheduler
immediately returns -EIO for new tasks.
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
After lockd is started, add a symlink for lockd's rpc_client under
NFS' superblock sysfs.
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
For the general and state management nfs_client under each mount, create
symlinks to their respective rpc_client sysfs entries.
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Create a sysfs directory for each mount that corresponds to the mount's
nfs_server struct. As the mount is being constructed, use the name
"server-n", but rename it to the "MAJOR:MINOR" of the mount after assigning
a device_id. The rename approach allows us to populate the mount's directory
with links to the various rpc_client objects during the mount's
construction. The naming convention (MAJOR:MINOR) can be used to reference
a particular NFS mount's sysfs tree.
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
The btrfs_inode_mod_outstanding_extents trace event only shows the modified
number to the number of outstanding extents. It would be helpful if we can
see the resulting extent number as well.
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Use the new TLS handshake API to enable the SunRPC client code
to request a TLS handshake. This implements support for RFC 9289,
only on TCP sockets.
Upper layers such as NFS use RPC-with-TLS to protect in-transit
traffic.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
The RPC header parser doesn't recognize TLS handshake traffic, so it
will close the connection prematurely with an error. To avoid that,
shunt the transport's data_ready callback when there is a TLS
handshake in progress.
The XPRT_SOCK_IGNORE_RECV flag will be toggled by code added in a
subsequent patch.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Overlayfs creates the real underlying files with fake f_path, whose
f_inode is on the underlying fs and f_path on overlayfs.
Those real files were open with FMODE_NONOTIFY, because fsnotify code was
not prapared to handle fsnotify hooks on files with fake path correctly
and fanotify would report unexpected event->fd with fake overlayfs path,
when the underlying fs was being watched.
Teach fsnotify to handle events on the real files, and do not set real
files to FMODE_NONOTIFY to allow operations on real file (e.g. open,
access, modify, close) to generate async and permission events.
Because fsnotify does not have notifications on address space
operations, we do not need to worry about ->vm_file not reporting
events to a watched overlayfs when users are accessing a mapped
overlayfs file.
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Message-Id: <20230615112229.2143178-6-amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Pass the upper layer's rpc_create_args to the rpc_clnt_new()
tracepoint so additional parts of the upper layer's request can be
recorded.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Add an initial set of policies along with fields for upper layers to
pass the requested policy down to the transport layer.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Overlayfs uses open_with_fake_path() to allocate internal kernel files,
with a "fake" path - whose f_path is not on the same fs as f_inode.
Allocate a container struct backing_file for those internal files, that
is used to hold the "fake" ovl path along with the real path.
backing_file_real_path() can be used to access the stored real path.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Message-Id: <20230615112229.2143178-5-amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
cachefiles uses kernel_open_tmpfile() to open kernel internal tmpfile
without accounting for nr_files.
cachefiles uses open_with_fake_path() for the same reason without the
need for a fake path.
Fork open_with_fake_path() to kernel_file_open() which only does the
noaccount part and use it in cachefiles.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Message-Id: <20230615112229.2143178-3-amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Overlayfs and cachefiles use vfs_open_tmpfile() to open a tmpfile
without accounting for nr_files.
Rename this helper to kernel_tmpfile_open() to better reflect this
helper is used for kernel internal users.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Message-Id: <20230615112229.2143178-2-amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Up until commit 6a45b0e258 ("gpiolib: Introduce
gpiochip_irqchip_add_domain()") all irq_domains were allocated
by gpiolib itself and thus gpiolib also takes care of freeing it.
With gpiochip_irqchip_add_domain() a user of gpiolib can associate an
irq_domain with the gpio_chip. This irq_domain is not managed by
gpiolib and therefore must not be freed by gpiolib.
Fixes: 6a45b0e258 ("gpiolib: Introduce gpiochip_irqchip_add_domain()")
Reported-by: Jiawen Wu <jiawenwu@trustnetic.com>
Signed-off-by: Michael Walle <mwalle@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Add a helper to complete an ordered_extent without first doing a lookup.
The tracepoint cannot use the ordered_extent class as we also want to
print the range.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
STA MLD setup links may get removed if AP MLD remove the corresponding
affiliated APs with Multi-Link reconfiguration as described in
P802.11be_D3.0, section 35.3.6.2.2 Removing affiliated APs. Currently,
there is no support to notify such operation to cfg80211 and userspace.
Add support for the drivers to indicate STA MLD setup links removal to
cfg80211 and notify the same to userspace. Upon receiving such
indication from the driver, clear the MLO links information of the
removed links in the WDEV.
Signed-off-by: Veerendranath Jakkam <quic_vjakkam@quicinc.com>
Link: https://lore.kernel.org/r/20230317142153.237900-1-quic_vjakkam@quicinc.com
[rename function and attribute, fix kernel-doc]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
