Fix netfs_write_single() and afs_single_writepages() to better handle a
write that would be skipped due to lock contention and WB_SYNC_NONE by
returning 1 from netfs_write_single() if it skipped and making
afs_single_writepages() skip also. If a skip occurs, the inode must be
re-marked as the VFS may have cleared the mark.
This is really only theoretical for directories in netfs_write_single() as
the only path to that is through afs_single_writepages() that takes the
->validate_lock around it, thereby serialising it.
Fixes: 6dd8093661 ("afs: Use netfslib for directories")
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-24-dhowells@redhat.com
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Under some circumstances, netfs_perform_write() doesn't correctly
manipulate folio->private between NULL, NETFS_FOLIO_COPY_TO_CACHE, pointing
to a group and pointing to a netfs_folio struct, leading to potential
multiple attachments of private data with associated folio ref leaks and
also leaks of netfs_folio structs or netfs_group refs.
Fix this by consolidating the place at which a folio is marked uptodate in
one place and having that look at what's attached to folio->private and
decide how to clean it up and then set the new group. Also, the content
shouldn't be flushed if group is NULL, even if a group is specified in the
netfs_group parameter, as that would be the case for a new folio. A
filesystem should always specify netfs_group or never specify netfs_group.
The Sashiko auto-review tool noted that it was theoretically possible that
the fpos >= ctx->zero_point section might leak if it modified a streaming
write folio. This is unlikely, but with a network filesystem, third party
changes can happen. It also pointed out that __netfs_set_group() would
leak if called multiple times on the same folio from the "whole folio
modify section".
Fixes: 8f52de0077 ("netfs: Reduce number of conditional branches in netfs_perform_write()")
Closes: https://sashiko.dev/#/patchset/20260414082004.3756080-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-22-dhowells@redhat.com
cc: Paulo Alcantara <pc@manguebit.org>
cc: Matthew Wilcox <willy@infradead.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
In netfs_invalidate_folio(), if the region of a partial invalidation
overlaps the front (but not all) of a dirty write cached in a streaming
write page (dirty, but not uptodate, with the dirty region tracked by a
netfs_folio struct), the function modifies the dirty region - but
incorrectly as it moves the region forward by setting the start to the
start, not the end, of the invalidation region.
Fix this by setting finfo->dirty_offset to the end of the invalidation
region (iend).
Fixes: cce6bfa6ca ("netfs: Fix trimming of streaming-write folios in netfs_inval_folio()")
Closes: https://sashiko.dev/#/patchset/20260414082004.3756080-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-21-dhowells@redhat.com
cc: Paulo Alcantara <pc@manguebit.org>
cc: Matthew Wilcox <willy@infradead.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
netfs_unlock_abandoned_read_pages(rreq) accesses the index of the folios it
is wanting to unlock and compares that to rreq->no_unlock_folio so that it
doesn't unlock a folio being read for netfs_perform_write() or
netfs_write_begin().
However, given that netfs_unlock_abandoned_read_pages() is called _after_
NETFS_RREQ_IN_PROGRESS is cleared, the one folio that it's not allowed to
dereference is the one specified by ->no_unlock_folio as ownership
immediately reverts to the caller.
Fix this by storing the folio pointer instead and using that rather than
the index. Also fix netfs_unlock_read_folio() where the same applies.
Fixes: ee4cdf7ba8 ("netfs: Speed up buffered reading")
Closes: https://sashiko.dev/#/patchset/20260414082004.3756080-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-20-dhowells@redhat.com
cc: Paulo Alcantara <pc@manguebit.org>
cc: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>
cc: Matthew Wilcox <willy@infradead.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Fix netfs_read_gaps() to release the sink page it uses after waiting for
the request to complete. The way the sink page is used is that an
ITER_BVEC-class iterator is created that has the gaps from the target folio
at either end, but has the sink page tiled over the middle so that a single
read op can fill in both gaps.
The bug was found by KASAN detecting a UAF on the generic/075 xfstest in
the cifsd kernel thread that handles reception of data from the TCP socket:
BUG: KASAN: use-after-free in _copy_to_iter+0x48a/0xa20
Write of size 885 at addr ffff888107f92000 by task cifsd/1285
CPU: 2 UID: 0 PID: 1285 Comm: cifsd Not tainted 7.0.0 #6 PREEMPT(lazy)
Call Trace:
dump_stack_lvl+0x5d/0x80
print_report+0x17f/0x4f1
kasan_report+0x100/0x1e0
kasan_check_range+0x10f/0x1e0
__asan_memcpy+0x3c/0x60
_copy_to_iter+0x48a/0xa20
__skb_datagram_iter+0x2c9/0x430
skb_copy_datagram_iter+0x6e/0x160
tcp_recvmsg_locked+0xce0/0x1130
tcp_recvmsg+0xeb/0x300
inet_recvmsg+0xcf/0x3a0
sock_recvmsg+0xea/0x100
cifs_readv_from_socket+0x3a6/0x4d0 [cifs]
cifs_read_iter_from_socket+0xdd/0x130 [cifs]
cifs_readv_receive+0xaad/0xb10 [cifs]
cifs_demultiplex_thread+0x1148/0x1740 [cifs]
kthread+0x1cf/0x210
Fixes: ee4cdf7ba8 ("netfs: Speed up buffered reading")
Reported-by: Steve French <sfrench@samba.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-18-dhowells@redhat.com
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
cc: Paulo Alcantara <pc@manguebit.org>
cc: Matthew Wilcox <willy@infradead.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
In netfs_perform_write(), "write streaming" (the caching of dirty data in
dirty but !uptodate folios) is performed to avoid the need to read data
that is just going to get immediately overwritten. However, this is/will
be disabled in three circumstances: if the fd is open O_RDWR, if fscache is
in use (as we need to round out the blocks for DIO) or if content
encryption is enabled (again for rounding out purposes).
The idea behind disabling it if the fd is open O_RDWR is that we'd need to
flush the write-streaming page before we could read the data, particularly
through mmap. But netfs now fills in the gaps if ->read_folio() is called
on the page, so that is unnecessary. Further, this doesn't actually work
if a separate fd is open for reading.
Fix this by removing the check for O_RDWR, thereby allowing streaming
writes even when we might read.
This caused a number of problems with the generic/522 xfstest, but those
are now fixed.
Fixes: c38f4e96e6 ("netfs: Provide func to copy data to pagecache for buffered write")
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-17-dhowells@redhat.com
cc: Paulo Alcantara <pc@manguebit.org>
cc: Matthew Wilcox <willy@infradead.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Fix netfs_read_gaps() to remove the netfs_folio record from the folio
record before marking the folio uptodate if it successfully fills the gaps
around the dirty data in a streaming write folio (dirty, but not uptodate).
Found with:
fsx -q -N 1000000 -p 10000 -o 128000 -l 600000 \
/xfstest.test/junk --replay-ops=junk.fsxops
using the following as junk.fsxops:
truncate 0x0 0x138b1 0x8b15d *
write 0x507ee 0x10df7 0x927c0
write 0x19993 0x10e04 0x927c0 *
mapwrite 0x66214 0x1a253 0x927c0
copy_range 0xb704 0x89b9 0x24429 0x79380
write 0x2402b 0x144a2 0x90660 *
mapwrite 0x204d5 0x140a0 0x927c0 *
copy_range 0x1f72c 0x137d0 0x7a906 0x927c0 *
read 0 0x9157c 0x9157c
on cifs with the default cache option.
It shows folio 0x24 misbehaving if the FMODE_READ check is commented out in
netfs_perform_write():
if (//(file->f_mode & FMODE_READ) ||
netfs_is_cache_enabled(ctx)) {
and no fscache. This was initially found with the generic/522 xfstest.
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-16-dhowells@redhat.com
Fixes: ee4cdf7ba8 ("netfs: Speed up buffered reading")
cc: Paulo Alcantara <pc@manguebit.org>
cc: Matthew Wilcox <willy@infradead.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Fix netfs_advance_writethrough() to always unlock the supplied folio and to
mark it dirty if it isn't yet written to the end. Unfortunately, it can't
be marked for writeback until the folio is done with as that may cause a
deadlock against mmapped reads and writes.
Even though it has been marked dirty, premature writeback can't occur as
the caller is holding both inode->i_rwsem (which will prevent concurrent
truncation, fallocation, DIO and other writes) and ictx->wb_lock (which
will cause flushing to wait and writeback to skip or wait).
Note that this may be easier to deal with once the queuing of folios is
split from the generation of subrequests.
Fixes: 288ace2f57 ("netfs: New writeback implementation")
Closes: https://sashiko.dev/#/patchset/20260427154639.180684-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-15-dhowells@redhat.com
cc: Paulo Alcantara <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
In order to avoid reading whilst writing, netfslib will allow "streaming
writes" in which dirty data is stored directly into folios without reading
them first. Such folios are marked dirty but may not be marked uptodate.
If a folio is entirely written by a streaming write, uptodate will be set,
otherwise it will have a netfs_folio struct attached to ->private recording
the dirty region.
In the event that a partially written streaming write page is to be
overwritten entirely by a single write(), netfs_perform_write() will try to
copy over it, but doesn't discard the netfs_folio if it succeeds; further,
it doesn't correctly handle a partial copy that overwrites some of the
dirty data.
Fix this by the following:
(1) If the folio is successfully overwritten, free the netfs_folio struct
before marking the page uptodate.
(2) If the copy to the folio partially fails, but short of the dirty data,
just ignore the copy.
(3) If the copy partially fails and overwrites some of the dirty data,
accept the copy, update the netfs_folio struct to record the new data.
If the folio is now filled, free the netfs_folio and set uptodate,
otherwise return a partial write.
Found with:
fsx -q -N 1000000 -p 10000 -o 128000 -l 600000 \
/xfstest.test/junk --replay-ops=junk.fsxops
using the following as junk.fsxops:
truncate 0x0 0 0x927c0
write 0x63fb8 0x53c8 0
copy_range 0xb704 0x19b9 0x24429 0x79380
write 0x2402b 0x144a2 0x90660 *
write 0x204d5 0x140a0 0x927c0 *
copy_range 0x1f72c 0x137d0 0x7a906 0x927c0 *
read 0x00000 0x20000 0x9157c
read 0x20000 0x20000 0x9157c
read 0x40000 0x20000 0x9157c
read 0x60000 0x20000 0x9157c
read 0x7e1a0 0xcfb9 0x9157c
on cifs with the default cache option.
It shows folio 0x24 misbehaving if the FMODE_READ check is commented out in
netfs_perform_write():
if (//(file->f_mode & FMODE_READ) ||
netfs_is_cache_enabled(ctx)) {
and no fscache. This was initially found with the generic/522 xfstest.
Fixes: 8f52de0077 ("netfs: Reduce number of conditional branches in netfs_perform_write()")
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-14-dhowells@redhat.com
cc: Paulo Alcantara <pc@manguebit.org>
cc: Matthew Wilcox <willy@infradead.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
If a streaming write is made, this will leave the relevant modified folio
in a not-uptodate, but dirty state with a netfs_folio struct hung off of
folio->private indicating the dirty range. Subsequently truncating the
file such that the dirty data in the folio is removed, but the first part
of the folio theoretically remains will cause the netfs_folio struct to be
discarded... but will leave the dirty flag set.
If the folio is then read via mmap(), netfs_read_folio() will see that the
page is dirty and jump to netfs_read_gaps() to fill in the missing bits.
netfs_read_gaps(), however, expects there to be a netfs_folio struct
present and can oops because truncate removed it.
Fix this by calling folio_cancel_dirty() in netfs_invalidate_folio() in the
event that all the dirty data in the folio is erased (as nfs does).
Also add some tracepoints to log modifications to a dirty page.
This can be reproduced with something like:
dd if=/dev/zero of=/xfstest.test/foo bs=1M count=1
umount /xfstest.test
mount /xfstest.test
xfs_io -c "w 0xbbbf 0xf96c" \
-c "truncate 0xbbbf" \
-c "mmap -r 0xb000 0x11000" \
-c "mr 0xb000 0x11000" \
/xfstest.test/foo
with fscaching disabled (otherwise streaming writes are suppressed) and a
change to netfs_perform_write() to disallow streaming writes if the fd is
open O_RDWR:
if (//(file->f_mode & FMODE_READ) || <--- comment this out
netfs_is_cache_enabled(ctx)) {
It should be reproducible even without this change, but if prevents the
above trivial xfs_io command from reproducing it.
Note that the initial dd is important: the file must start out sufficiently
large that the zero-point logic doesn't just clear the gaps because it
knows there's nothing in the file to read yet. Unmounting and mounting is
needed to clear the pagecache (there are other ways to do that that may
also work).
This was initially reproduced with the generic/522 xfstest on some patches
that remove the FMODE_READ restriction.
Fixes: 9ebff83e64 ("netfs: Prep to use folio->private for write grouping and streaming write")
Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-12-dhowells@redhat.com
cc: Paulo Alcantara <pc@manguebit.org>
cc: Matthew Wilcox <willy@infradead.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
In netfs_extract_user_iter(), if iov_iter_extract_pages() failed to
extract user pages, bail out on -ENOMEM, otherwise return the error
code only if @npages == 0, allowing short DIO reads and writes to be
issued.
This fixes mmapstress02 from LTP tests against CIFS.
Fixes: 85dd2c8ff3 ("netfs: Add a function to extract a UBUF or IOVEC into a BVEC iterator")
Reported-by: Xiaoli Feng <xifeng@redhat.com>
Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-10-dhowells@redhat.com
Cc: netfs@lists.linux.dev
Cc: stable@vger.kernel.org
Cc: linux-cifs@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Fix the update of the zero point[*] by netfs_release_folio() when there is
uncommitted data in the pagecache beyond the folio being released but the
on-server EOF is in this folio (ie. i_size > remote_i_size). The update
needs to limit zero_point to remote_i_size, not i_size as i_size is a local
phenomenon reflecting updates made locally to the pagecache, not stuff
written to the server. remote_i_size tracks the server's i_size.
[*] The zero point is the file position from which we can assume that the
server will just return zeros, so we can avoid generating reads.
Note that netfs_invalidate_folio() probably doesn't need fixing as
zero_point should be updated by setattr after truncation or fallocate.
Found with:
fsx -q -N 1000000 -p 10000 -o 128000 -l 600000 \
/xfstest.test/junk --replay-ops=junk.fsxops
using the following as junk.fsxops:
truncate 0x0 0x1bbae 0x82864
write 0x3ef2e 0xf9c8 0x1bbae
write 0x67e05 0xcb5a 0x4e8f6
mapread 0x57781 0x85b6 0x7495f
copy_range 0x5d3d 0x10329 0x54fac 0x7495f
write 0x64710 0x1c2b 0x7495f
mapread 0x64000 0x1000 0x7495f
on cifs with the default cache option.
It shows read-gaps on folio 0x64 failing with a short read (ie. it hits
EOF) if the FMODE_READ check is commented out in netfs_perform_write():
if (//(file->f_mode & FMODE_READ) ||
netfs_is_cache_enabled(ctx)) {
and no fscache. This was initially found with the generic/522 xfstest.
Fixes: cce6bfa6ca ("netfs: Fix trimming of streaming-write folios in netfs_inval_folio()")
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-7-dhowells@redhat.com
cc: Paulo Alcantara <pc@manguebit.org>
cc: Matthew Wilcox <willy@infradead.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Fix potential tearing in using ->remote_i_size and ->zero_point by copying
i_size_read() and i_size_write() and using the same seqcount as for i_size.
We need to make sure that netfslib and the filesystems that use it always
hold i_lock whilst updating any of the sizes to prevent i_size_seqcount
from getting corrupted.
Fixes: 4058f74210 ("netfs: Keep track of the actual remote file size")
Fixes: 100ccd18bb ("netfs: Optimise away reads above the point at which there can be no data")
Closes: https://sashiko.dev/#/patchset/20260414082004.3756080-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-6-dhowells@redhat.com
cc: Paulo Alcantara <pc@manguebit.org>
cc: Matthew Wilcox <willy@infradead.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
The list of subrequests attached to stream->subrequests is accessed without
locks by netfs_collect_read_results() and netfs_collect_write_results(),
and then they access subreq->flags without taking a barrier after getting
the subreq pointer from the list. Relatedly, the functions that build the
list don't use any sort of write barrier when constructing the list to make
sure that the NETFS_SREQ_IN_PROGRESS flag is perceived to be set first if
no lock is taken.
Fix this by:
(1) Add a new list_add_tail_release() function that uses a release barrier
to set the pointer to the new member of the list.
(2) Add a new list_first_entry_or_null_acquire() function that uses an
acquire barrier to read the pointer to the first member in a list (or
return NULL).
(3) Use list_add_tail_release() when adding a subreq to ->subrequests.
(4) Use list_first_entry_or_null_acquire() when initially accessing the
front of the list (when an item is removed, the pointer to the new
front iterm is obtained under the same lock).
Fixes: e2d46f2ec3 ("netfs: Change the read result collector to only use one work item")
Fixes: 288ace2f57 ("netfs: New writeback implementation")
Link: https://sashiko.dev/#/patchset/20260326104544.509518-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-4-dhowells@redhat.com
cc: Paulo Alcantara <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
When the preparation of a new subrequest for a read fails, if the
subrequest has already been added to the stream->subrequests list, it can't
simply be put and abandoned as the collector may see it. Also, if it
hasn't been queued yet, it has two outstanding refs that both need to be
put. Both DIO read and single-read dispatch fail at this; further, both
differ in the order they do things to the way buffered read works.
Fix cancellation of both DIO-read and single-read subrequests that failed
preparation by the following steps:
(1) Harmonise all three reads (buffered, dio, single) to queue the subreq
before prepping it.
(2) Make all three call netfs_queue_read() to do the queuing.
(3) Set NETFS_RREQ_ALL_QUEUED independently of the queuing as we don't
know the length of the subreq at this point.
(4) In all cases, set the error and NETFS_SREQ_FAILED flag on the subreq
and then call netfs_read_subreq_terminated() to deal with it. This
will pass responsibility off to the collector for dealing with it.
Fixes: e2d46f2ec3 ("netfs: Change the read result collector to only use one work item")
Closes: https://sashiko.dev/#/patchset/20260425125426.3855807-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-2-dhowells@redhat.com
cc: Paulo Alcantara <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Everything:
Total patches: 368
Reviews/patch: 1.56
Reviewed rate: 74%
Excluding DAMON:
Total patches: 316
Reviews/patch: 1.77
Reviewed rate: 81%
Excluding DAMON and zram:
Total patches: 306
Reviews/patch: 1.81
Reviewed rate: 82%
Excluding DAMON, zram and maple_tree:
Total patches: 276
Reviews/patch: 2.01
Reviewed rate: 91%
Significant patch series in this merge:
- The 30 patch series "maple_tree: Replace big node with maple copy"
from Liam Howlett is mainly prepararatory work for ongoing development
but it does reduce stack usage and is an improvement.
- The 12 patch series "mm, swap: swap table phase III: remove swap_map"
from Kairui Song offers memory savings by removing the static swap_map.
It also yields some CPU savings and implements several cleanups.
- The 2 patch series "mm: memfd_luo: preserve file seals" from Pratyush
Yadav adds file seal preservation to LUO's memfd code.
- The 2 patch series "mm: zswap: add per-memcg stat for incompressible
pages" from Jiayuan Chen adds additional userspace stats reportng to
zswap.
- The 4 patch series "arch, mm: consolidate empty_zero_page" from Mike
Rapoport implements some cleanups for our handling of ZERO_PAGE() and
zero_pfn.
- The 2 patch series "mm/kmemleak: Improve scan_should_stop()
implementation" from Zhongqiu Han provides an robustness improvement and
some cleanups in the kmemleak code.
- The 4 patch series "Improve khugepaged scan logic" from Vernon Yang
"improves the khugepaged scan logic and reduces CPU consumption by
prioritizing scanning tasks that access memory frequently".
- The 2 patch series "Make KHO Stateless" from Jason Miu simplifies
Kexec Handover by "transitioning KHO from an xarray-based metadata
tracking system with serialization to a radix tree data structure that
can be passed directly to the next kernel"
- The 3 patch series "mm: vmscan: add PID and cgroup ID to vmscan
tracepoints" from Thomas Ballasi and Steven Rostedt enhances vmscan's
tracepointing.
- The 5 patch series "mm: arch/shstk: Common shadow stack mapping helper
and VM_NOHUGEPAGE" from Catalin Marinas is a cleanup for the shadow
stack code: remove per-arch code in favour of a generic implementation.
- The 2 patch series "Fix KASAN support for KHO restored vmalloc
regions" from Pasha Tatashin fixes a WARN() which can be emitted the KHO
restores a vmalloc area.
- The 4 patch series "mm: Remove stray references to pagevec" from Tal
Zussman provides several cleanups, mainly udpating references to "struct
pagevec", which became folio_batch three years ago.
- The 17 patch series "mm: Eliminate fake head pages from vmemmap
optimization" from Kiryl Shutsemau simplifies the HugeTLB vmemmap
optimization (HVO) by changing how tail pages encode their relationship
to the head page.
- The 2 patch series "mm/damon/core: improve DAMOS quota efficiency for
core layer filters" from SeongJae Park improves two problematic
behaviors of DAMOS that makes it less efficient when core layer filters
are used.
- The 3 patch series "mm/damon: strictly respect min_nr_regions" from
SeongJae Park improves DAMON usability by extending the treatment of the
min_nr_regions user-settable parameter.
- The 3 patch series "mm/page_alloc: pcp locking cleanup" from Vlastimil
Babka is a proper fix for a previously hotfixed SMP=n issue. Code
simplifications and cleanups ennsed.
- The 16 patch series "mm: cleanups around unmapping / zapping" from
David Hildenbrand implements "a bunch of cleanups around unmapping and
zapping. Mostly simplifications, code movements, documentation and
renaming of zapping functions".
- The 6 patch series "support batched checking of the young flag for
MGLRU" from Baolin Wang supports batched checking of the young flag for
MGLRU. It's part cleanups; one benchmark shows large performance
benefits for arm64.
- The 5 patch series "memcg: obj stock and slab stat caching cleanups"
from Johannes Weiner provides memcg cleanup and robustness improvements.
- The 5 patch series "Allow order zero pages in page reporting" from
Yuvraj Sakshith enhances page_reporting's free page reporting - it is
presently and undesirably order-0 pages when reporting free memory.
- The 6 patch series "mm: vma flag tweaks" from Lorenzo Stoakes is
cleanup work following from the recent conversion of the VMA flags to a
bitmap.
- The 10 patch series "mm/damon: add optional debugging-purpose sanity
checks" from SeongJae Park adds some more developer-facing debug checks
into DAMON core.
- The 2 patch series "mm/damon: test and document power-of-2
min_region_sz requirement" from SeongJae Park adds an additional DAMON
kunit test and makes some adjustments to the addr_unit parameter
handling.
- The 3 patch series "mm/damon/core: make passed_sample_intervals
comparisons overflow-safe" from SeongJae Park fixes a hard-to-hit time
overflow issue in DAMON core.
- The 7 patch series "mm/damon: improve/fixup/update ratio calculation,
test and documentation" from SeongJae Park is a "batch of misc/minor
improvements and fixups" for DAMON.
- The 4 patch series "mm: move vma_(kernel|mmu)_pagesize() out of
hugetlb.c" from David Hildenbrand fixes a possible issue with dax-device
when CONFIG_HUGETLB=n. Some code movement was required.
- The 6 patch series "zram: recompression cleanups and tweaks" from
Sergey Senozhatsky provides "a somewhat random mix of fixups,
recompression cleanups and improvements" in the zram code.
- The 11 patch series "mm/damon: support multiple goal-based quota
tuning algorithms" from SeongJae Park extend DAMOS quotas goal
auto-tuning to support multiple tuning algorithms that users can select.
- The 4 patch series "mm: thp: reduce unnecessary
start_stop_khugepaged()" from Breno Leitao fixes the khugpaged sysfs
handling so we no longer spam the logs with reams of junk when
starting/stopping khugepaged.
- The 3 patch series "mm: improve map count checks" from Lorenzo Stoakes
provides some cleanups and slight fixes in the mremap, mmap and vma
code.
- The 5 patch series "mm/damon: support addr_unit on default monitoring
targets for modules" from SeongJae Park extends the use of DAMON core's
addr_unit tunable.
- The 5 patch series "mm: khugepaged cleanups and mTHP prerequisites"
from Nico Pache provides cleanups in the khugepaged and is a base for
Nico's planned khugepaged mTHP support.
- The 15 patch series "mm: memory hot(un)plug and SPARSEMEM cleanups"
from David Hildenbrand implements code movement and cleanups in the
memhotplug and sparsemem code.
- The 2 patch series "mm: remove CONFIG_ARCH_ENABLE_MEMORY_HOTREMOVE and
cleanup CONFIG_MIGRATION" from David Hildenbrand rationalizes some
memhotplug Kconfig support.
- The 6 patch series "change young flag check functions to return bool"
from Baolin Wang is "a cleanup patchset to change all young flag check
functions to return bool".
- The 3 patch series "mm/damon/sysfs: fix memory leak and NULL
dereference issues" from Josh Law and SeongJae Park fixes a few
potential DAMON bugs.
- The 25 patch series "mm/vma: convert vm_flags_t to vma_flags_t in vma
code" from "converts a lot of the existing use of the legacy vm_flags_t
data type to the new vma_flags_t type which replaces it". Mainly in the
vma code.
- The 21 patch series "mm: expand mmap_prepare functionality and usage"
from Lorenzo Stoakes "expands the mmap_prepare functionality, which is
intended to replace the deprecated f_op->mmap hook which has been the
source of bugs and security issues for some time". Cleanups,
documentation, extension of mmap_prepare into filesystem drivers.
- The 13 patch series "mm/huge_memory: refactor zap_huge_pmd()" from
Lorenzo Stoakes simplifies and cleans up zap_huge_pmd(). Additional
cleanups around vm_normal_folio_pmd() and the softleaf functionality are
performed.
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Merge tag 'mm-stable-2026-04-13-21-45' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- "maple_tree: Replace big node with maple copy" (Liam Howlett)
Mainly prepararatory work for ongoing development but it does reduce
stack usage and is an improvement.
- "mm, swap: swap table phase III: remove swap_map" (Kairui Song)
Offers memory savings by removing the static swap_map. It also yields
some CPU savings and implements several cleanups.
- "mm: memfd_luo: preserve file seals" (Pratyush Yadav)
File seal preservation to LUO's memfd code
- "mm: zswap: add per-memcg stat for incompressible pages" (Jiayuan
Chen)
Additional userspace stats reportng to zswap
- "arch, mm: consolidate empty_zero_page" (Mike Rapoport)
Some cleanups for our handling of ZERO_PAGE() and zero_pfn
- "mm/kmemleak: Improve scan_should_stop() implementation" (Zhongqiu
Han)
A robustness improvement and some cleanups in the kmemleak code
- "Improve khugepaged scan logic" (Vernon Yang)
Improve khugepaged scan logic and reduce CPU consumption by
prioritizing scanning tasks that access memory frequently
- "Make KHO Stateless" (Jason Miu)
Simplify Kexec Handover by transitioning KHO from an xarray-based
metadata tracking system with serialization to a radix tree data
structure that can be passed directly to the next kernel
- "mm: vmscan: add PID and cgroup ID to vmscan tracepoints" (Thomas
Ballasi and Steven Rostedt)
Enhance vmscan's tracepointing
- "mm: arch/shstk: Common shadow stack mapping helper and
VM_NOHUGEPAGE" (Catalin Marinas)
Cleanup for the shadow stack code: remove per-arch code in favour of
a generic implementation
- "Fix KASAN support for KHO restored vmalloc regions" (Pasha Tatashin)
Fix a WARN() which can be emitted the KHO restores a vmalloc area
- "mm: Remove stray references to pagevec" (Tal Zussman)
Several cleanups, mainly udpating references to "struct pagevec",
which became folio_batch three years ago
- "mm: Eliminate fake head pages from vmemmap optimization" (Kiryl
Shutsemau)
Simplify the HugeTLB vmemmap optimization (HVO) by changing how tail
pages encode their relationship to the head page
- "mm/damon/core: improve DAMOS quota efficiency for core layer
filters" (SeongJae Park)
Improve two problematic behaviors of DAMOS that makes it less
efficient when core layer filters are used
- "mm/damon: strictly respect min_nr_regions" (SeongJae Park)
Improve DAMON usability by extending the treatment of the
min_nr_regions user-settable parameter
- "mm/page_alloc: pcp locking cleanup" (Vlastimil Babka)
The proper fix for a previously hotfixed SMP=n issue. Code
simplifications and cleanups ensued
- "mm: cleanups around unmapping / zapping" (David Hildenbrand)
A bunch of cleanups around unmapping and zapping. Mostly
simplifications, code movements, documentation and renaming of
zapping functions
- "support batched checking of the young flag for MGLRU" (Baolin Wang)
Batched checking of the young flag for MGLRU. It's part cleanups; one
benchmark shows large performance benefits for arm64
- "memcg: obj stock and slab stat caching cleanups" (Johannes Weiner)
memcg cleanup and robustness improvements
- "Allow order zero pages in page reporting" (Yuvraj Sakshith)
Enhance free page reporting - it is presently and undesirably order-0
pages when reporting free memory.
- "mm: vma flag tweaks" (Lorenzo Stoakes)
Cleanup work following from the recent conversion of the VMA flags to
a bitmap
- "mm/damon: add optional debugging-purpose sanity checks" (SeongJae
Park)
Add some more developer-facing debug checks into DAMON core
- "mm/damon: test and document power-of-2 min_region_sz requirement"
(SeongJae Park)
An additional DAMON kunit test and makes some adjustments to the
addr_unit parameter handling
- "mm/damon/core: make passed_sample_intervals comparisons
overflow-safe" (SeongJae Park)
Fix a hard-to-hit time overflow issue in DAMON core
- "mm/damon: improve/fixup/update ratio calculation, test and
documentation" (SeongJae Park)
A batch of misc/minor improvements and fixups for DAMON
- "mm: move vma_(kernel|mmu)_pagesize() out of hugetlb.c" (David
Hildenbrand)
Fix a possible issue with dax-device when CONFIG_HUGETLB=n. Some code
movement was required.
- "zram: recompression cleanups and tweaks" (Sergey Senozhatsky)
A somewhat random mix of fixups, recompression cleanups and
improvements in the zram code
- "mm/damon: support multiple goal-based quota tuning algorithms"
(SeongJae Park)
Extend DAMOS quotas goal auto-tuning to support multiple tuning
algorithms that users can select
- "mm: thp: reduce unnecessary start_stop_khugepaged()" (Breno Leitao)
Fix the khugpaged sysfs handling so we no longer spam the logs with
reams of junk when starting/stopping khugepaged
- "mm: improve map count checks" (Lorenzo Stoakes)
Provide some cleanups and slight fixes in the mremap, mmap and vma
code
- "mm/damon: support addr_unit on default monitoring targets for
modules" (SeongJae Park)
Extend the use of DAMON core's addr_unit tunable
- "mm: khugepaged cleanups and mTHP prerequisites" (Nico Pache)
Cleanups to khugepaged and is a base for Nico's planned khugepaged
mTHP support
- "mm: memory hot(un)plug and SPARSEMEM cleanups" (David Hildenbrand)
Code movement and cleanups in the memhotplug and sparsemem code
- "mm: remove CONFIG_ARCH_ENABLE_MEMORY_HOTREMOVE and cleanup
CONFIG_MIGRATION" (David Hildenbrand)
Rationalize some memhotplug Kconfig support
- "change young flag check functions to return bool" (Baolin Wang)
Cleanups to change all young flag check functions to return bool
- "mm/damon/sysfs: fix memory leak and NULL dereference issues" (Josh
Law and SeongJae Park)
Fix a few potential DAMON bugs
- "mm/vma: convert vm_flags_t to vma_flags_t in vma code" (Lorenzo
Stoakes)
Convert a lot of the existing use of the legacy vm_flags_t data type
to the new vma_flags_t type which replaces it. Mainly in the vma
code.
- "mm: expand mmap_prepare functionality and usage" (Lorenzo Stoakes)
Expand the mmap_prepare functionality, which is intended to replace
the deprecated f_op->mmap hook which has been the source of bugs and
security issues for some time. Cleanups, documentation, extension of
mmap_prepare into filesystem drivers
- "mm/huge_memory: refactor zap_huge_pmd()" (Lorenzo Stoakes)
Simplify and clean up zap_huge_pmd(). Additional cleanups around
vm_normal_folio_pmd() and the softleaf functionality are performed.
* tag 'mm-stable-2026-04-13-21-45' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits)
mm: fix deferred split queue races during migration
mm/khugepaged: fix issue with tracking lock
mm/huge_memory: add and use has_deposited_pgtable()
mm/huge_memory: add and use normal_or_softleaf_folio_pmd()
mm: add softleaf_is_valid_pmd_entry(), pmd_to_softleaf_folio()
mm/huge_memory: separate out the folio part of zap_huge_pmd()
mm/huge_memory: use mm instead of tlb->mm
mm/huge_memory: remove unnecessary sanity checks
mm/huge_memory: deduplicate zap deposited table call
mm/huge_memory: remove unnecessary VM_BUG_ON_PAGE()
mm/huge_memory: add a common exit path to zap_huge_pmd()
mm/huge_memory: handle buggy PMD entry in zap_huge_pmd()
mm/huge_memory: have zap_huge_pmd return a boolean, add kdoc
mm/huge: avoid big else branch in zap_huge_pmd()
mm/huge_memory: simplify vma_is_specal_huge()
mm: on remap assert that input range within the proposed VMA
mm: add mmap_action_map_kernel_pages[_full]()
uio: replace deprecated mmap hook with mmap_prepare in uio_info
drivers: hv: vmbus: replace deprecated mmap hook with mmap_prepare
mm: allow handling of stacked mmap_prepare hooks in more drivers
...
Remove unused pagevec.h includes from .c files. These were found with
the following command:
grep -rl '#include.*pagevec\.h' --include='*.c' | while read f; do
grep -qE 'PAGEVEC_SIZE|folio_batch' "$f" || echo "$f"
done
There are probably more removal candidates in .h files, but those are
more complex to analyze.
Link: https://lkml.kernel.org/r/20260225-pagevec_cleanup-v2-2-716868cc2d11@columbia.edu
Signed-off-by: Tal Zussman <tz2294@columbia.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Zi Yan <ziy@nvidia.com>
Acked-by: Chris Li <chrisl@kernel.org>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand (Arm) <david@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The netfs_io_stream::front member is meant to point to the subrequest
currently being collected on a stream, but it isn't actually used this way
by direct write (which mostly ignores it). However, there's a tracepoint
which looks at it. Further, stream->front is actually redundant with
stream->subrequests.next.
Fix the potential problem in the direct code by just removing the member
and using stream->subrequests.next instead, thereby also simplifying the
code.
Fixes: a0b4c7a491 ("netfs: Fix unbuffered/DIO writes to dispatch subrequests in strict sequence")
Reported-by: Paulo Alcantara <pc@manguebit.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/4158599.1774426817@warthog.procyon.org.uk
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Under certain circumstances, all the remaining subrequests from a read
request will get abandoned during retry. The abandonment process expects
the 'subreq' variable to be set to the place to start abandonment from, but
it doesn't always have a useful value (it will be uninitialised on the
first pass through the loop and it may point to a deleted subrequest on
later passes).
Fix the first jump to "abandon:" to set subreq to the start of the first
subrequest expected to need retry (which, in this abandonment case, turned
out unexpectedly to no longer have NEED_RETRY set).
Also clear the subreq pointer after discarding superfluous retryable
subrequests to cause an oops if we do try to access it.
Fixes: ee4cdf7ba8 ("netfs: Speed up buffered reading")
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/3775287.1773848338@warthog.procyon.org.uk
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
cc: Paulo Alcantara <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
When a write subrequest is marked NETFS_SREQ_NEED_RETRY, the retry path
in netfs_unbuffered_write() unconditionally calls stream->prepare_write()
without checking if it is NULL.
Filesystems such as 9P do not set the prepare_write operation, so
stream->prepare_write remains NULL. When get_user_pages() fails with
-EFAULT and the subrequest is flagged for retry, this results in a NULL
pointer dereference at fs/netfs/direct_write.c:189.
Fix this by mirroring the pattern already used in write_retry.c: if
stream->prepare_write is NULL, skip renegotiation and directly reissue
the subrequest via netfs_reissue_write(), which handles iterator reset,
IN_PROGRESS flag, stats update and reissue internally.
Fixes: a0b4c7a491 ("netfs: Fix unbuffered/DIO writes to dispatch subrequests in strict sequence")
Reported-by: syzbot+7227db0fbac9f348dba0@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=7227db0fbac9f348dba0
Signed-off-by: Deepanshu Kartikey <Kartikey406@gmail.com>
Link: https://patch.msgid.link/20260307043947.347092-1-kartikey406@gmail.com
Tested-by: syzbot+7227db0fbac9f348dba0@syzkaller.appspotmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
When a process crashes and the kernel writes a core dump to a 9P
filesystem, __kernel_write() creates an ITER_KVEC iterator. This
iterator reaches netfs_limit_iter() via netfs_unbuffered_write(), which
only handles ITER_FOLIOQ, ITER_BVEC and ITER_XARRAY iterator types,
hitting the BUG() for any other type.
Fix this by adding netfs_limit_kvec() following the same pattern as
netfs_limit_bvec(), since both kvec and bvec are simple segment arrays
with pointer and length fields. Dispatch it from netfs_limit_iter() when
the iterator type is ITER_KVEC.
Fixes: cae932d3ae ("netfs: Add func to calculate pagecount/size-limited span of an iterator")
Reported-by: syzbot+9c058f0d63475adc97fd@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=9c058f0d63475adc97fd
Tested-by: syzbot+9c058f0d63475adc97fd@syzkaller.appspotmail.com
Signed-off-by: Deepanshu Kartikey <Kartikey406@gmail.com>
Link: https://patch.msgid.link/20260307090041.359870-1-kartikey406@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Fix netfslib such that when it's making an unbuffered or DIO write, to make
sure that it sends each subrequest strictly sequentially, waiting till the
previous one is 'committed' before sending the next so that we don't have
pieces landing out of order and potentially leaving a hole if an error
occurs (ENOSPC for example).
This is done by copying in just those bits of issuing, collecting and
retrying subrequests that are necessary to do one subrequest at a time.
Retrying, in particular, is simpler because if the current subrequest needs
retrying, the source iterator can just be copied again and the subrequest
prepped and issued again without needing to be concerned about whether it
needs merging with the previous or next in the sequence.
Note that the issuing loop waits for a subrequest to complete right after
issuing it, but this wait could be moved elsewhere allowing preparatory
steps to be performed whilst the subrequest is in progress. In particular,
once content encryption is available in netfslib, that could be done whilst
waiting, as could cleanup of buffers that have been completed.
Fixes: 153a9961b5 ("netfs: Implement unbuffered/DIO write support")
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/58526.1772112753@warthog.procyon.org.uk
Tested-by: Steve French <sfrench@samba.org>
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This is the exact same thing as the 'alloc_obj()' version, only much
smaller because there are a lot fewer users of the *alloc_flex()
interface.
As with alloc_obj() version, this was done entirely with mindless brute
force, using the same script, except using 'flex' in the pattern rather
than 'objs*'.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This was done entirely with mindless brute force, using
git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'
to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.
Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.
For the same reason the 'flex' versions will be done as a separate
conversion.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:
Single allocations: kmalloc(sizeof(TYPE), ...)
are replaced with: kmalloc_obj(TYPE, ...)
Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with: kmalloc_objs(TYPE, COUNT, ...)
Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...)
(where TYPE may also be *VAR)
The resulting allocations no longer return "void *", instead returning
"TYPE *".
Signed-off-by: Kees Cook <kees@kernel.org>
This change fixes the instance of double incrementing of
retry_count. The increment of this count already happens
when netfs_reissue_write gets called. Incrementing this
value before is not necessary.
Fixes: 4acb665cf4 ("netfs: Work around recursion by abandoning retry if nothing read")
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
The *_subreq_terminated functions today only process the NEED_RETRY
flag when the subreq was successful or failed with EAGAIN error.
However, there could be other retriable errors for network filesystems.
Avoid this by processing the NEED_RETRY irrespective of the error
code faced by the subreq. If it was specifically marked for retry,
the error code must not matter.
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
The read result collection for buffered reads seems to run ahead of the
completion of subrequests under some circumstances, as can be seen in the
following log snippet:
9p_client_res: client 18446612686390831168 response P9_TREAD tag 0 err 0
...
netfs_sreq: R=00001b55[1] DOWN TERM f=192 s=0 5fb2/5fb2 s=5 e=0
...
netfs_collect_folio: R=00001b55 ix=00004 r=4000-5000 t=4000/5fb2
netfs_folio: i=157f3 ix=00004-00004 read-done
netfs_folio: i=157f3 ix=00004-00004 read-unlock
netfs_collect_folio: R=00001b55 ix=00005 r=5000-5fb2 t=5000/5fb2
netfs_folio: i=157f3 ix=00005-00005 read-done
netfs_folio: i=157f3 ix=00005-00005 read-unlock
...
netfs_collect_stream: R=00001b55[0:] cto=5fb2 frn=ffffffff
netfs_collect_state: R=00001b55 col=5fb2 cln=6000 n=c
netfs_collect_stream: R=00001b55[0:] cto=5fb2 frn=ffffffff
netfs_collect_state: R=00001b55 col=5fb2 cln=6000 n=8
...
netfs_sreq: R=00001b55[2] ZERO SUBMT f=000 s=5fb2 0/4e s=0 e=0
netfs_sreq: R=00001b55[2] ZERO TERM f=102 s=5fb2 4e/4e s=5 e=0
The 'cto=5fb2' indicates the collected file pos we've collected results to
so far - but we still have 0x4e more bytes to go - so we shouldn't have
collected folio ix=00005 yet. The 'ZERO' subreq that clears the tail
happens after we unlock the folio, allowing the application to see the
uncleared tail through mmap.
The problem is that netfs_read_unlock_folios() will unlock a folio in which
the amount of read results collected hits EOF position - but the ZERO
subreq lies beyond that and so happens after.
Fix this by changing the end check to always be the end of the folio and
never the end of the file.
In the future, I should look at clearing to the end of the folio here rather
than adding a ZERO subreq to do this. On the other hand, the ZERO subreq can
run in parallel with an async READ subreq. Further, the ZERO subreq may still
be necessary to, say, handle extents in a ceph file that don't have any
backing store and are thus implicitly all zeros.
This can be reproduced by creating a file, the size of which doesn't align
to a page boundary, e.g. 24998 (0x5fb2) bytes and then doing something
like:
xfs_io -c "mmap -r 0 0x6000" -c "madvise -d 0 0x6000" \
-c "mread -v 0 0x6000" /xfstest.test/x
The last 0x4e bytes should all be 00, but if the tail hasn't been cleared
yet, you may see rubbish there. This can be reproduced with kafs by
modifying the kernel to disable the call to netfs_read_subreq_progress()
and to stop afs_issue_read() from doing the async call for NETFS_READAHEAD.
Reproduction can be made easier by inserting an mdelay(100) in
netfs_issue_read() for the ZERO-subreq case.
AFS and CIFS are normally unlikely to show this as they dispatch READ ops
asynchronously, which allows the ZERO-subreq to finish first. 9P's READ op is
completely synchronous, so the ZERO-subreq will always happen after. It isn't
seen all the time, though, because the collection may be done in a worker
thread.
Reported-by: Christian Schoenebeck <linux_oss@crudebyte.com>
Link: https://lore.kernel.org/r/8622834.T7Z3S40VBb@weasel/
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/938162.1766233900@warthog.procyon.org.uk
Fixes: e2d46f2ec3 ("netfs: Change the read result collector to only use one work item")
Tested-by: Christian Schoenebeck <linux_oss@crudebyte.com>
Acked-by: Dominique Martinet <asmadeus@codewreck.org>
Suggested-by: Dominique Martinet <asmadeus@codewreck.org>
cc: Dominique Martinet <asmadeus@codewreck.org>
cc: Christian Schoenebeck <linux_oss@crudebyte.com>
cc: v9fs@lists.linux.dev
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Merge tag 'vfs-6.19-rc1.folio' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull folio updates from Christian Brauner:
"Add a new folio_next_pos() helper function that returns the file
position of the first byte after the current folio. This is a common
operation in filesystems when needing to know the end of the current
folio.
The helper is lifted from btrfs which already had its own version, and
is now used across multiple filesystems and subsystems:
- btrfs
- buffer
- ext4
- f2fs
- gfs2
- iomap
- netfs
- xfs
- mm
This fixes a long-standing bug in ocfs2 on 32-bit systems with files
larger than 2GiB. Presumably this is not a common configuration, but
the fix is backported anyway. The other filesystems did not have bugs,
they were just mildly inefficient.
This also introduce uoff_t as the unsigned version of loff_t. A recent
commit inadvertently changed a comparison from being unsigned (on
64-bit systems) to being signed (which it had always been on 32-bit
systems), leading to sporadic fstests failures.
Generally file sizes are restricted to being a signed integer, but in
places where -1 is passed to indicate "up to the end of the file", it
is convenient to have an unsigned type to ensure comparisons are
always unsigned regardless of architecture"
* tag 'vfs-6.19-rc1.folio' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fs: Add uoff_t
mm: Use folio_next_pos()
xfs: Use folio_next_pos()
netfs: Use folio_next_pos()
iomap: Use folio_next_pos()
gfs2: Use folio_next_pos()
f2fs: Use folio_next_pos()
ext4: Use folio_next_pos()
buffer: Use folio_next_pos()
btrfs: Use folio_next_pos()
filemap: Add folio_next_pos()
This is one instruction more efficient than open-coding folio_pos() +
folio_size(). It's the equivalent of (x + y) << z rather than
x << z + y << z.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://patch.msgid.link/20251024170822.1427218-9-willy@infradead.org
Acked-by: David Howells <dhowells@redhat.com>
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Paulo Alcantara <pc@manguebit.org>
Cc: netfs@lists.linux.dev
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Merge tag 'vfs-6.18-rc1.workqueue' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs workqueue updates from Christian Brauner:
"This contains various workqueue changes affecting the filesystem
layer.
Currently if a user enqueue a work item using schedule_delayed_work()
the used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies
to schedule_work() that is using system_wq and queue_work(), that
makes use again of WORK_CPU_UNBOUND.
This replaces the use of system_wq and system_unbound_wq. system_wq is
a per-CPU workqueue which isn't very obvious from the name and
system_unbound_wq is to be used when locality is not required.
So this renames system_wq to system_percpu_wq, and system_unbound_wq
to system_dfl_wq.
This also adds a new WQ_PERCPU flag to allow the fs subsystem users to
explicitly request the use of per-CPU behavior. Both WQ_UNBOUND and
WQ_PERCPU flags coexist for one release cycle to allow callers to
transition their calls. WQ_UNBOUND will be removed in a next release
cycle"
* tag 'vfs-6.18-rc1.workqueue' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fs: WQ_PERCPU added to alloc_workqueue users
fs: replace use of system_wq with system_percpu_wq
fs: replace use of system_unbound_wq with system_dfl_wq
Commit 20d72b00ca ("netfs: Fix the request's work item to not
require a ref") modified netfs_alloc_request() to initialize the
reference counter to 2 instead of 1. The rationale was that the
requet's "work" would release the second reference after completion
(via netfs_{read,write}_collection_worker()). That works most of the
time if all goes well.
However, it leaks this additional reference if the request is released
before the I/O operation has been submitted: the error code path only
decrements the reference counter once and the work item will never be
queued because there will never be a completion.
This has caused outages of our whole server cluster today because
tasks were blocked in netfs_wait_for_outstanding_io(), leading to
deadlocks in Ceph (another bug that I will address soon in another
patch). This was caused by a netfs_pgpriv2_begin_copy_to_cache() call
which failed in fscache_begin_write_operation(). The leaked
netfs_io_request was never completed, leaving `netfs_inode.io_count`
with a positive value forever.
All of this is super-fragile code. Finding out which code paths will
lead to an eventual completion and which do not is hard to see:
- Some functions like netfs_create_write_req() allocate a request, but
will never submit any I/O.
- netfs_unbuffered_read_iter_locked() calls netfs_unbuffered_read()
and then netfs_put_request(); however, netfs_unbuffered_read() can
also fail early before submitting the I/O request, therefore another
netfs_put_request() call must be added there.
A rule of thumb is that functions that return a `netfs_io_request` do
not submit I/O, and all of their callers must be checked.
For my taste, the whole netfs code needs an overhaul to make reference
counting easier to understand and less fragile & obscure. But to fix
this bug here and now and produce a patch that is adequate for a
stable backport, I tried a minimal approach that quickly frees the
request object upon early failure.
I decided against adding a second netfs_put_request() each time
because that would cause code duplication which obscures the code
further. Instead, I added the function netfs_put_failed_request()
which frees such a failed request synchronously under the assumption
that the reference count is exactly 2 (as initially set by
netfs_alloc_request() and never touched), verified by a
WARN_ON_ONCE(). It then deinitializes the request object (without
going through the "cleanup_work" indirection) and frees the allocation
(with RCU protection to protect against concurrent access by
netfs_requests_seq_start()).
All code paths that fail early have been changed to call
netfs_put_failed_request() instead of netfs_put_request().
Additionally, I have added a netfs_put_request() call to
netfs_unbuffered_read() as explained above because the
netfs_put_failed_request() approach does not work there.
Fixes: 20d72b00ca ("netfs: Fix the request's work item to not require a ref")
Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Paulo Alcantara <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
cc: stable@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.
This lack of consistentcy cannot be addressed without refactoring the API.
system_unbound_wq should be the default workqueue so as not to enforce
locality constraints for random work whenever it's not required.
Adding system_dfl_wq to encourage its use when unbound work should be used.
The old system_unbound_wq will be kept for a few release cycles.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Link: https://lore.kernel.org/20250916082906.77439-2-marco.crivellari@suse.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
The filio lock has been released here, so there is no need to jump to
error_folio_unlock to release it again.
Reported-by: syzbot+b73c7d94a151e2ee1e9b@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=b73c7d94a151e2ee1e9b
Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com>
Acked-by: David Howells <dhowells@redhat.com>
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
If all the subrequests in an unbuffered write stream fail, the subrequest
collector doesn't update the stream->transferred value and it retains its
initial LONG_MAX value. Unfortunately, if all active streams fail, then we
take the smallest value of { LONG_MAX, LONG_MAX, ... } as the value to set
in wreq->transferred - which is then returned from ->write_iter().
LONG_MAX was chosen as the initial value so that all the streams can be
quickly assessed by taking the smallest value of all stream->transferred -
but this only works if we've set any of them.
Fix this by adding a flag to indicate whether the value in
stream->transferred is valid and checking that when we integrate the
values. stream->transferred can then be initialised to zero.
This was found by running the generic/750 xfstest against cifs with
cache=none. It splices data to the target file. Once (if) it has used up
all the available scratch space, the writes start failing with ENOSPC.
This causes ->write_iter() to fail. However, it was returning
wreq->transferred, i.e. LONG_MAX, rather than an error (because it thought
the amount transferred was non-zero) and iter_file_splice_write() would
then try to clean up that amount of pipe bufferage - leading to an oops
when it overran. The kernel log showed:
CIFS: VFS: Send error in write = -28
followed by:
BUG: kernel NULL pointer dereference, address: 0000000000000008
with:
RIP: 0010:iter_file_splice_write+0x3a4/0x520
do_splice+0x197/0x4e0
or:
RIP: 0010:pipe_buf_release (include/linux/pipe_fs_i.h:282)
iter_file_splice_write (fs/splice.c:755)
Also put a warning check into splice to announce if ->write_iter() returned
that it had written more than it was asked to.
Fixes: 288ace2f57 ("netfs: New writeback implementation")
Reported-by: Xiaoli Feng <fengxiaoli0714@gmail.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220445
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/915443.1755207950@warthog.procyon.org.uk
cc: Paulo Alcantara <pc@manguebit.org>
cc: Steve French <sfrench@samba.org>
cc: Shyam Prasad N <sprasad@microsoft.com>
cc: netfs@lists.linux.dev
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
cc: stable@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
When netfslib is issuing subrequests, the subrequests start processing
immediately and may complete before we reach the end of the issuing
function. At the end of the issuing function we set NETFS_RREQ_ALL_QUEUED
to indicate to the collector that we aren't going to issue any more subreqs
and that it can do the final notifications and cleanup.
Now, this isn't a problem if the request is synchronous
(NETFS_RREQ_OFFLOAD_COLLECTION is unset) as the result collection will be
done in-thread and we're guaranteed an opportunity to run the collector.
However, if the request is asynchronous, collection is primarily triggered
by the termination of subrequests queuing it on a workqueue. Now, a race
can occur here if the app thread sets ALL_QUEUED after the last subrequest
terminates.
This can happen most easily with the copy2cache code (as used by Ceph)
where, in the collection routine of a read request, an asynchronous write
request is spawned to copy data to the cache. Folios are added to the
write request as they're unlocked, but there may be a delay before
ALL_QUEUED is set as the write subrequests may complete before we get
there.
If all the write subreqs have finished by the ALL_QUEUED point, no further
events happen and the collection never happens, leaving the request
hanging.
Fix this by queuing the collector after setting ALL_QUEUED. This is a bit
heavy-handed and it may be sufficient to do it only if there are no extant
subreqs.
Also add a tracepoint to cross-reference both requests in a copy-to-request
operation and add a trace to the netfs_rreq tracepoint to indicate the
setting of ALL_QUEUED.
Fixes: e2d46f2ec3 ("netfs: Change the read result collector to only use one work item")
Reported-by: Max Kellermann <max.kellermann@ionos.com>
Link: https://lore.kernel.org/r/CAKPOu+8z_ijTLHdiCYGU_Uk7yYD=shxyGLwfe-L7AV3DhebS3w@mail.gmail.com/
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/20250711151005.2956810-3-dhowells@redhat.com
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
cc: Paulo Alcantara <pc@manguebit.org>
cc: Viacheslav Dubeyko <slava@dubeyko.com>
cc: Alex Markuze <amarkuze@redhat.com>
cc: Ilya Dryomov <idryomov@gmail.com>
cc: netfs@lists.linux.dev
cc: ceph-devel@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
cc: stable@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
The netfs copy-to-cache that is used by Ceph with local caching sets up a
new request to write data just read to the cache. The request is started
and then left to look after itself whilst the app continues. The request
gets notified by the backing fs upon completion of the async DIO write, but
then tries to wake up the app because NETFS_RREQ_OFFLOAD_COLLECTION isn't
set - but the app isn't waiting there, and so the request just hangs.
Fix this by setting NETFS_RREQ_OFFLOAD_COLLECTION which causes the
notification from the backing filesystem to put the collection onto a work
queue instead.
Fixes: e2d46f2ec3 ("netfs: Change the read result collector to only use one work item")
Reported-by: Max Kellermann <max.kellermann@ionos.com>
Link: https://lore.kernel.org/r/CAKPOu+8z_ijTLHdiCYGU_Uk7yYD=shxyGLwfe-L7AV3DhebS3w@mail.gmail.com/
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/20250711151005.2956810-2-dhowells@redhat.com
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
cc: Paulo Alcantara <pc@manguebit.org>
cc: Viacheslav Dubeyko <slava@dubeyko.com>
cc: Alex Markuze <amarkuze@redhat.com>
cc: Ilya Dryomov <idryomov@gmail.com>
cc: netfs@lists.linux.dev
cc: ceph-devel@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
cc: stable@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Make a number of updates to the netfs tracepoints:
(1) Remove a duplicate trace from netfs_unbuffered_write_iter_locked().
(2) Move the trace in netfs_wake_rreq_flag() to after the flag is cleared
so that the change appears in the trace.
(3) Differentiate the use of netfs_rreq_trace_wait/woke_queue symbols.
(4) Don't do so many trace emissions in the wait functions as some of them
are redundant.
(5) In netfs_collect_read_results(), differentiate a subreq that's being
abandoned vs one that has been consumed in a regular way.
(6) Add a tracepoint to indicate the call to ->ki_complete().
(7) Don't double-increment the subreq_counter when retrying a write.
(8) Move the netfs_sreq_trace_io_progress tracepoint within cifs code to
just MID_RESPONSE_RECEIVED and add different tracepoints for other MID
states and note check failure.
Signed-off-by: David Howells <dhowells@redhat.com>
Co-developed-by: Paulo Alcantara <pc@manguebit.org>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>
Link: https://lore.kernel.org/20250701163852.2171681-14-dhowells@redhat.com
cc: Steve French <sfrench@samba.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
cc: linux-cifs@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Renumber the NETFS_RREQ_* flags to put the most useful status bits in the
bottom nibble - and therefore the last hex digit in the trace output -
making it easier to grasp the state at a glance.
In particular, put the IN_PROGRESS flag in bit 0 and ALL_QUEUED at bit 1.
Also make the flags field in /proc/fs/netfs/requests larger to accommodate
all the flags.
Also make the flags field in the netfs_sreq tracepoint larger to
accommodate all the NETFS_SREQ_* flags.
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/20250701163852.2171681-13-dhowells@redhat.com
Reviewed-by: Paulo Alcantara <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Netfslib has two functions for updating the i_size after a write: one for
buffered writes into the pagecache and one for direct/unbuffered writes.
However, what needs to be done is much the same in both cases, so merge
them together.
This does raise one question, though: should updating the i_size after a
direct write do the same estimated update of i_blocks as is done for
buffered writes.
Also get rid of the cleanup function pointer from netfs_io_request as it's
only used for direct write to update i_size; instead do the i_size setting
directly from write collection.
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/20250701163852.2171681-12-dhowells@redhat.com
cc: Steve French <sfrench@samba.org>
cc: Paulo Alcantara <pc@manguebit.org>
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Fix the updating of i_size, particularly in regard to the completion of DIO
writes and especially async DIO writes by using a lock.
The bug is triggered occasionally by the generic/207 xfstest as it chucks a
bunch of AIO DIO writes at the filesystem and then checks that fstat()
returns a reasonable st_size as each completes.
The problem is that netfs is trying to do "if new_size > inode->i_size,
update inode->i_size" sort of thing but without a lock around it.
This can be seen with cifs, but shouldn't be seen with kafs because kafs
serialises modification ops on the client whereas cifs sends the requests
to the server as they're generated and lets the server order them.
Fixes: 153a9961b5 ("netfs: Implement unbuffered/DIO write support")
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/20250701163852.2171681-11-dhowells@redhat.com
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
cc: Steve French <sfrench@samba.org>
cc: Paulo Alcantara <pc@manguebit.org>
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
