This is a backport from Ming. Here is Ming's changelog:
JIRA: https://redhat.atlassian.net/browse/RHEL-161185
Conflicts: io_uring/kbuf.c
- Upstream uses kfree(buf) to free the orphaned buffer; downstream
allocates io_buffer from the io_buf_cachep slab cache, so
kmem_cache_free(io_buf_cachep, buf) is used instead.
- Upstream removed the req->buf_index assignment entirely; downstream
still needs it for the next buffer selection, so it is kept but moved
before the conditional to avoid use-after-free on buf->bgid.
- Upstream has bl->nbufs++ tracking which does not exist downstream;
dropped from the backport.
commit c2c185be5c85d37215397c8e8781abf0a69bec1f
Author: Jens Axboe <axboe@kernel.dk>
Date: Thu Mar 12 08:59:25 2026 -0600
io_uring/kbuf: check if target buffer list is still legacy on recycle
There's a gap between when the buffer was grabbed and when it
potentially gets recycled, where if the list is empty, someone
could've upgraded it to a ring provided type. The legacy recycling
doesn't check if the buffer_list still exists and is of the right
type. Add those checks.
Cc: stable@vger.kernel.org
Reported-by: Keenan Dong <keenanat2000@gmail.com>
Fixes: c7fb19428d67 ("io_uring: add support for ring mapped supplied buffers")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-141266
Conflicts: We already backported this commit, but missed the portions
of the kbuf handling in kbuf.h. This brings in those changes in a way
that aligns with the upstream code as it exists today. This should aid
reviewers in verifying correctness.
Upstream-status: RHEL only
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-141266
commit b14fad555302a2104948feaff70503b64c80ac01
Author: Prithvi Tambewagh <activprithvi@gmail.com>
Date: Thu Dec 25 12:58:29 2025 +0530
io_uring: fix filename leak in __io_openat_prep()
__io_openat_prep() allocates a struct filename using getname(). However,
for the condition of the file being installed in the fixed file table as
well as having O_CLOEXEC flag set, the function returns early. At that
point, the request doesn't have REQ_F_NEED_CLEANUP flag set. Due to this,
the memory for the newly allocated struct filename is not cleaned up,
causing a memory leak.
Fix this by setting the REQ_F_NEED_CLEANUP for the request just after the
successful getname() call, so that when the request is torn down, the
filename will be cleaned up, along with other resources needing cleanup.
Reported-by: syzbot+00e61c43eb5e4740438f@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=00e61c43eb5e4740438f
Tested-by: syzbot+00e61c43eb5e4740438f@syzkaller.appspotmail.com
Cc: stable@vger.kernel.org
Signed-off-by: Prithvi Tambewagh <activprithvi@gmail.com>
Fixes: b9445598d8c6 ("io_uring: openat directly into fixed fd table")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-141266
commit e15cb2200b934e507273510ba6bc747d5cde24a3
Author: Jens Axboe <axboe@kernel.dk>
Date: Tue Dec 9 13:25:23 2025 -0700
io_uring: fix min_wait wakeups for SQPOLL
Using min_wait, two timeouts are given:
1) The min_wait timeout, within which up to 'wait_nr' events are
waited for.
2) The overall long timeout, which is entered if no events are generated
in the min_wait window.
If the min_wait has expired, any event being posted must wake the task.
For SQPOLL, that isn't the case, as it won't trigger the io_has_work()
condition, as it will have already processed the task_work that happened
when an event was posted. This causes any event to trigger post the
min_wait to not always cause the waiting application to wakeup, and
instead it will wait until the overall timeout has expired. This can be
shown in a test case that has a 1 second min_wait, with a 5 second
overall wait, even if an event triggers after 1.5 seconds:
axboe@m2max-kvm /d/iouring-mre (master)> zig-out/bin/iouring
info: MIN_TIMEOUT supported: true, features: 0x3ffff
info: Testing: min_wait=1000ms, timeout=5s, wait_nr=4
info: 1 cqes in 5000.2ms
where the expected result should be:
axboe@m2max-kvm /d/iouring-mre (master)> zig-out/bin/iouring
info: MIN_TIMEOUT supported: true, features: 0x3ffff
info: Testing: min_wait=1000ms, timeout=5s, wait_nr=4
info: 1 cqes in 1500.3ms
When the min_wait timeout triggers, reset the number of completions
needed to wake the task. This should ensure that any future events will
wake the task, regardless of how many events it originally wanted to
wait for.
Reported-by: Tip ten Brink <tip@tenbrinkmeijs.com>
Cc: stable@vger.kernel.org
Fixes: 1100c4a2656d ("io_uring: add support for batch wait timeout")
Link: https://github.com/axboe/liburing/issues/1477
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-141266
Conflicts: RHEL does not have the incremental buffer commit introduced
in cf9536e550dd2 ("io_uring/kbuf: enable bundles for incrementally
consumed buffers"), so that hunk is elided. There are other
differences due to missing commits 5fda51255439a ("io_uring/kbuf:
switch to storing struct io_buffer_list locally") and ab6559bdbb08f
("io_uring/kbuf: introduce struct io_br_sel").
commit 78385c7299f7514697d196b3233a91bd5e485591
Author: Caleb Sander Mateos <csander@purestorage.com>
Date: Thu Dec 4 15:43:31 2025 -0700
io_uring/kbuf: use READ_ONCE() for userspace-mapped memory
The struct io_uring_buf elements in a buffer ring are in a memory region
accessible from userspace. A malicious/buggy userspace program could
therefore write to them at any time, so they should be accessed with
READ_ONCE() in the kernel. Commit 98b6fa62c84f ("io_uring/kbuf: always
use READ_ONCE() to read ring provided buffer lengths") already switched
the reads of the len field to READ_ONCE(). Do the same for bid and addr.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Fixes: c7fb19428d67 ("io_uring: add support for ring mapped supplied buffers")
Cc: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-141266
commit 525916ce496615f531091855604eab9ca573b195
Author: Joanne Koong <joannelkoong@gmail.com>
Date: Thu Dec 4 13:51:16 2025 -0800
io_uring/rsrc: fix lost entries after cloned range
When cloning with node replacements (IORING_REGISTER_DST_REPLACE),
destination entries after the cloned range are not copied over.
Add logic to copy them over to the new destination table.
Fixes: c1329532d5aa ("io_uring/rsrc: allow cloning with node replacements")
Cc: stable@vger.kernel.org
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-141266
commit 84230ad2d2afbf0c44c32967e525c0ad92e26b4e
Author: Jens Axboe <axboe@kernel.dk>
Date: Mon Dec 1 13:25:22 2025 -0700
io_uring/poll: correctly handle io_poll_add() return value on update
When the core of io_uring was updated to handle completions
consistently and with fixed return codes, the POLL_REMOVE opcode
with updates got slightly broken. If a POLL_ADD is pending and
then POLL_REMOVE is used to update the events of that request, if that
update causes the POLL_ADD to now trigger, then that completion is lost
and a CQE is never posted.
Additionally, ensure that if an update does cause an existing POLL_ADD
to complete, that the completion value isn't always overwritten with
-ECANCELED. For that case, whatever io_poll_add() set the value to
should just be retained.
Cc: stable@vger.kernel.org
Fixes: 97b388d70b53 ("io_uring: handle completions in the core")
Reported-by: syzbot+641eec6b7af1f62f2b99@syzkaller.appspotmail.com
Tested-by: syzbot+641eec6b7af1f62f2b99@syzkaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-141266
commit 93e197e524b14d185d011813b72773a1a49d932d
Author: Pavel Begunkov <asml.silence@gmail.com>
Date: Thu Nov 6 12:58:19 2025 +0000
io_uring: use WRITE_ONCE for user shared memory
IORING_SETUP_NO_MMAP rings remain user accessible even before the ctx
setup is finalised, so use WRITE_ONCE consistently when initialising
rings.
Fixes: 03d89a2de25bb ("io_uring: support for user allocated memory for rings/sqes")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-141266
commit c5efc6a0b3940381d67887302ddb87a5cf623685
Author: Alok Tiwari <alok.a.tiwari@oracle.com>
Date: Thu Oct 23 04:55:24 2025 -0700
io_uring: correct __must_hold annotation in io_install_fixed_file
The __must_hold annotation references &req->ctx->uring_lock, but req
is not in scope in io_install_fixed_file. This change updates the
annotation to reference the correct ctx->uring_lock.
improving code clarity.
Fixes: f110ed8498af ("io_uring: split out fixed file installation and removal")
Signed-off-by: Alok Tiwari <alok.a.tiwari@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-141266
commit a94e0657269c5b8e1a90b17aa2c048b3d276e16d
Author: Jens Axboe <axboe@kernel.dk>
Date: Tue Oct 21 11:44:39 2025 -0600
io_uring/sqpoll: be smarter on when to update the stime usage
The current approach is a bit naive, and hence calls the time querying
way too often. Only start the "doing work" timer when there's actual
work to do, and then use that information to terminate (and account) the
work time once done. This greatly reduces the frequency of these calls,
when they cannot have changed anyway.
Running a basic random reader that is setup to use SQPOLL, a profile
before this change shows these as the top cycle consumers:
+ 32.60% iou-sqp-1074 [kernel.kallsyms] [k] thread_group_cputime_adjusted
+ 19.97% iou-sqp-1074 [kernel.kallsyms] [k] thread_group_cputime
+ 12.20% io_uring io_uring [.] submitter_uring_fn
+ 4.13% iou-sqp-1074 [kernel.kallsyms] [k] getrusage
+ 2.45% iou-sqp-1074 [kernel.kallsyms] [k] io_submit_sqes
+ 2.18% iou-sqp-1074 [kernel.kallsyms] [k] __pi_memset_generic
+ 2.09% iou-sqp-1074 [kernel.kallsyms] [k] cputime_adjust
and after this change, top of profile looks as follows:
+ 36.23% io_uring io_uring [.] submitter_uring_fn
+ 23.26% iou-sqp-819 [kernel.kallsyms] [k] io_sq_thread
+ 10.14% iou-sqp-819 [kernel.kallsyms] [k] io_sq_tw
+ 6.52% iou-sqp-819 [kernel.kallsyms] [k] tctx_task_work_run
+ 4.82% iou-sqp-819 [kernel.kallsyms] [k] nvme_submit_cmds.part.0
+ 2.91% iou-sqp-819 [kernel.kallsyms] [k] io_submit_sqes
[...]
0.02% iou-sqp-819 [kernel.kallsyms] [k] cputime_adjust
where it's spending the cycles on things that actually matter.
Reported-by: Fengnan Chang <changfengnan@bytedance.com>
Cc: stable@vger.kernel.org
Fixes: 3fcb9d17206e ("io_uring/sqpoll: statistics of the true utilization of sq threads")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-141266
Conflicts: Contextual differences due to missing commit 3a3f61ce5e0b4
("exec: Make sure task->comm is always NUL-terminated").
commit 8ac9b0d33e5c0a995338ee5f25fe1b6ff7d97f65
Author: Jens Axboe <axboe@kernel.dk>
Date: Tue Oct 21 07:16:08 2025 -0600
io_uring/sqpoll: switch away from getrusage() for CPU accounting
getrusage() does a lot more than what the SQPOLL accounting needs, the
latter only cares about (and uses) the stime. Rather than do a full
RUSAGE_SELF summation, just query the used stime instead.
Cc: stable@vger.kernel.org
Fixes: 3fcb9d17206e ("io_uring/sqpoll: statistics of the true utilization of sq threads")
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-141266
commit 2c139a47eff8de24e3350dadb4c9d5e3426db826
Author: Yang Xiuwei <yangxiuwei@kylinos.cn>
Date: Fri Sep 19 17:03:52 2025 +0800
io_uring: fix incorrect io_kiocb reference in io_link_skb
In io_link_skb function, there is a bug where prev_notif is incorrectly
assigned using 'nd' instead of 'prev_nd'. This causes the context
validation check to compare the current notification with itself instead
of comparing it with the previous notification.
Fix by using the correct prev_nd parameter when obtaining prev_notif.
Signed-off-by: Yang Xiuwei <yangxiuwei@kylinos.cn>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Fixes: 6fe4220912d19 ("io_uring/notif: implement notification stacking")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-141266
commit 3539b1467e94336d5854ebf976d9627bfb65d6c3
Author: Jens Axboe <axboe@kernel.dk>
Date: Thu Sep 18 10:21:14 2025 -0600
io_uring: include dying ring in task_work "should cancel" state
When running task_work for an exiting task, rather than perform the
issue retry attempt, the task_work is canceled. However, this isn't
done for a ring that has been closed. This can lead to requests being
successfully completed post the ring being closed, which is somewhat
confusing and surprising to an application.
Rather than just check the task exit state, also include the ring
ref state in deciding whether or not to terminate a given request when
run from task_work.
Cc: stable@vger.kernel.org # 6.1+
Link: https://github.com/axboe/liburing/discussions/1459
Reported-by: Benedek Thaler <thaler@thaler.hu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-141266
commit 41b70df5b38bc80967d2e0ed55cc3c3896bba781
Author: Jens Axboe <axboe@kernel.dk>
Date: Tue Aug 12 08:30:11 2025 -0600
io_uring/net: commit partial buffers on retry
Ring provided buffers are potentially only valid within the single
execution context in which they were acquired. io_uring deals with this
and invalidates them on retry. But on the networking side, if
MSG_WAITALL is set, or if the socket is of the streaming type and too
little was processed, then it will hang on to the buffer rather than
recycle or commit it. This is problematic for two reasons:
1) If someone unregisters the provided buffer ring before a later retry,
then the req->buf_list will no longer be valid.
2) If multiple sockers are using the same buffer group, then multiple
receives can consume the same memory. This can cause data corruption
in the application, as either receive could land in the same
userspace buffer.
Fix this by disallowing partial retries from pinning a provided buffer
across multiple executions, if ring provided buffers are used.
Cc: stable@vger.kernel.org
Reported-by: pt x <superman.xpt@gmail.com>
Fixes: c56e022c0a27 ("io_uring: add support for user mapped provided buffer ring")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-141266
Conflicts: RHEL does not have epoll_wait or pipe support, so those
hunks are elided.
commit 8bb9d6ccd36062d16baa707b759809e1f494017e
Author: Jens Axboe <axboe@kernel.dk>
Date: Thu May 8 14:48:33 2025 -0600
io_uring: finish IOU_OK -> IOU_COMPLETE transition
IOU_COMPLETE is more descriptive, in that it explicitly says that the
return value means "please post a completion for this request". This
patch completes the transition from IOU_OK to IOU_COMPLETE, replacing
existing IOU_OK users.
This is a purely mechanical change.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-141266
Conflicts: RHEL does not have recvzc support, so those hunks are
elided. RHEL is also missing commit 185523ebc8534 ("io_uring/net:
canonise accept mshot handling"), which changes context in the
io_accept hunk.
commit 5027d02452c982bdc7b36205c66466ebd7e6ee17
Author: Pavel Begunkov <asml.silence@gmail.com>
Date: Sat Mar 8 17:19:33 2025 +0000
io_uring: unify STOP_MULTISHOT with IOU_OK
IOU_OK means that the request ownership is now handed back to core
io_uring and it has to complete it using the result provided in
req->cqe. Same is true for multishot and IOU_STOP_MULTISHOT.
Rename it into IOU_COMPLETE to avoid confusion and use for both modes.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e6a5b2edb0eb9558acb1c8f1db38ac45fee95491.1741453534.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-141266
Conflicts: RHEL does not yet have io_recvzc support, added via upstream
commit 11ed914bbf948 ("io_uring/zcrx: add io_recvzc request"), so the
hunk touching that function was dropped.
commit 7a9dcb05f5501b07a2ef7d0ef743f4f17e9f3055
Author: Pavel Begunkov <asml.silence@gmail.com>
Date: Sat Mar 8 17:19:32 2025 +0000
io_uring: return -EAGAIN to continue multishot
Multishot errors can be mapped 1:1 to normal errors, but there are not
identical. It leads to a peculiar situation where all multishot requests
has to check in what context they're run and return different codes.
Unify them starting with EAGAIN / IOU_ISSUE_SKIP_COMPLETE(EIOCBQUEUED)
pair, which mean that core io_uring still owns the request and it should
be retried. In case of multishot it's naturally just continues to poll,
otherwise it might poll, use iowq or do any other kind of allowed
blocking. Introduce IOU_RETRY aliased to -EAGAIN for that.
Apart from obvious upsides, multishot can now also check for misuse of
IOU_ISSUE_SKIP_COMPLETE.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/da117b79ce72ecc3ab488c744e29fae9ba54e23b.1741453534.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 4ec703ec0c384a2199808c4eb2e9037236285a8d
Author: Alok Tiwari <alok.a.tiwari@oracle.com>
Date: Sat Oct 18 12:32:54 2025 -0700
io_uring: fix incorrect unlikely() usage in io_waitid_prep()
The negation operator is incorrectly placed outside the unlikely()
macro:
if (!unlikely(iwa))
This inverts the compiler branch prediction hint, marking the NULL case
as likely instead of unlikely. The intent is to indicate that allocation
failures are rare, consistent with common kernel patterns.
Moving the negation inside unlikely():
if (unlikely(!iwa))
Fixes: 2b4fc4cd43f2 ("io_uring/waitid: setup async data in the prep handler")
Signed-off-by: Alok Tiwari <alok.a.tiwari@oracle.com>
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit be7cab44ed099566c605a8dac686c3254db01b35
Author: Pavel Begunkov <asml.silence@gmail.com>
Date: Wed Oct 15 13:07:23 2025 +0100
io_uring: protect mem region deregistration
io_create_region_mmap_safe() protects publishing of a region against
concurrent mmap calls, however we should also protect against it when
removing a region. There is a gap io_register_mem_region() where it
safely publishes a region, but then copy_to_user goes wrong and it
unsafely frees the region.
Cc: stable@vger.kernel.org
Fixes: 087f997870a94 ("io_uring/memmap: implement mmap for regions")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 927069c4ac2cd1a37efa468596fb5b8f86db9df0
Author: Jens Axboe <axboe@kernel.dk>
Date: Mon Oct 13 12:05:31 2025 -0600
Revert "io_uring/rw: drop -EOPNOTSUPP check in __io_complete_rw_common()"
This reverts commit 90bfb28d5fa8127a113a140c9791ea0b40ab156a.
Kevin reports that this commit causes an issue for him with LVM
snapshots, most likely because of turning off NOWAIT support while a
snapshot is being created. This makes -EOPNOTSUPP bubble back through
the completion handler, where io_uring read/write handling should just
retry it.
Reinstate the previous check removed by the referenced commit.
Cc: stable@vger.kernel.org
Fixes: 90bfb28d5fa8 ("io_uring/rw: drop -EOPNOTSUPP check in __io_complete_rw_common()")
Reported-by: Salvatore Bonaccorso <carnil@debian.org>
Reported-by: Kevin Lumik <kevin@xf.ee>
Link: https://lore.kernel.org/io-uring/cceb723c-051b-4de2-9a4c-4aa82e1619ee@kernel.dk/
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
Conflicts: RHEL does not have commit 3a4689ac109f1 ("io_uring/cmd: add
iovec cache for commands"), which results in a context difference.
commit df8922afc37aa2111ca79a216653a629146763ad
Author: Jens Axboe <axboe@kernel.dk>
Date: Thu Sep 18 13:59:15 2025 -0600
io_uring/msg_ring: kill alloc_cache for io_kiocb allocations
A recent commit:
fc582cd26e88 ("io_uring/msg_ring: ensure io_kiocb freeing is deferred for RCU")
fixed an issue with not deferring freeing of io_kiocb structs that
msg_ring allocates to after the current RCU grace period. But this only
covers requests that don't end up in the allocation cache. If a request
goes into the alloc cache, it can get reused before it is sane to do so.
A recent syzbot report would seem to indicate that there's something
there, however it may very well just be because of the KASAN poisoning
that the alloc_cache handles manually.
Rather than attempt to make the alloc_cache sane for that use case, just
drop the usage of the alloc_cache for msg_ring request payload data.
Fixes: 50cf5f3842af ("io_uring/msg_ring: add an alloc cache for io_kiocb entries")
Link: https://lore.kernel.org/io-uring/68cc2687.050a0220.139b6.0005.GAE@google.com/
Reported-by: syzbot+baa2e0f4e02df602583e@syzkaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
Conflicts: RHEL does not have commit cf9536e550dd2 ("io_uring/kbuf:
enable bundles for incrementally consumed buffers"), so that hunk is
elided.
commit 98b6fa62c84f2e129161e976a5b9b3cb4ccd117b
Author: Jens Axboe <axboe@kernel.dk>
Date: Wed Aug 27 15:27:30 2025 -0600
io_uring/kbuf: always use READ_ONCE() to read ring provided buffer lengths
Since the buffers are mapped from userspace, it is prudent to use
READ_ONCE() to read the value into a local variable, and use that for
any other actions taken. Having a stable read of the buffer length
avoids worrying about it changing after checking, or being read multiple
times.
Similarly, the buffer may well change in between it being picked and
being committed. Ensure the looping for incremental ring buffer commit
stops if it hits a zero sized buffer, as no further progress can be made
at that point.
Fixes: ae98dbf43d75 ("io_uring/kbuf: add support for incremental buffer consumption")
Link: https://lore.kernel.org/io-uring/tencent_000C02641F6250C856D0C26228DE29A3D30A@qq.com/
Reported-by: Qingyue Zhang <chunzhennn@qq.com>
Reported-by: Suoxing Zhang <aftern00n@qq.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
Conflicts: Upstream reworked the bit definitions. I assigned the first
available bit to FMODE_HAS_METADATA (0x800000).
commit d072148a8631f102de60ed5a3a827e85d09d24f0
Author: Christoph Hellwig <hch@lst.de>
Date: Tue Aug 19 10:25:00 2025 +0200
fs: add a FMODE_ flag to indicate IOCB_HAS_METADATA availability
Currently the kernel will happily route io_uring requests with metadata
to file operations that don't support it. Add a FMODE_ flag to guard
that.
Fixes: 4de2ce04c862 ("fs: introduce IOCB_HAS_METADATA for metadata")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/20250819082517.2038819-2-hch@lst.de
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 51a4598ad5d9eb6be4ec9ba65bbfdf0ac302eb2e
Author: Jens Axboe <axboe@kernel.dk>
Date: Fri Jun 20 07:41:21 2025 -0600
io_uring/net: always use current transfer count for buffer put
A previous fix corrected the retry condition for when to continue a
current bundle, but it missed that the current (not the total) transfer
count also applies to the buffer put. If not, then for incrementally
consumed buffer rings repeated completions on the same request may end
up over consuming.
Reported-by: Roy Tang (ErgoniaTrading) <royonia@ergonia.io>
Cc: stable@vger.kernel.org
Fixes: 3a08988123c8 ("io_uring/net: only retry recv bundle for a full transfer")
Link: https://github.com/axboe/liburing/issues/1423
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 33503c083fda048c77903460ac0429e1e2c0e341
Author: Jens Axboe <axboe@kernel.dk>
Date: Fri Aug 8 06:35:14 2025 -0600
io_uring/memmap: cast nr_pages to size_t before shifting
If the allocated size exceeds UINT_MAX, then it's necessary to cast
the mr->nr_pages value to size_t to prevent it from overflowing. In
practice this isn't much of a concern as the required memory size will
have been validated upfront, and accounted to the user. And > 4GB sizes
will be necessary to make the lack of a cast a problem, which greatly
exceeds normal user locked_vm settings that are generally in the kb to
mb range. However, if root is used, then accounting isn't done, and
then it's possible to hit this issue.
Link: https://lore.kernel.org/all/6895b298.050a0220.7f033.0059.GAE@google.com/
Cc: stable@vger.kernel.org
Reported-by: syzbot+23727438116feb13df15@syzkaller.appspotmail.com
Fixes: 087f997870a9 ("io_uring/memmap: implement mmap for regions")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit c7cafd5b81cc07fb402e3068d134c21e60ea688c
Author: Pavel Begunkov <asml.silence@gmail.com>
Date: Wed Jul 16 17:20:17 2025 +0100
io_uring/poll: fix POLLERR handling
8c8492ca64e7 ("io_uring/net: don't retry connect operation on EPOLLERR")
is a little dirty hack that
1) wrongfully assumes that POLLERR equals to a failed request, which
breaks all POLLERR users, e.g. all error queue recv interfaces.
2) deviates the connection request behaviour from connect(2), and
3) racy and solved at a wrong level.
Nothing can be done with 2) now, and 3) is beyond the scope of the
patch. At least solve 1) by moving the hack out of generic poll handling
into io_connect().
Cc: stable@vger.kernel.org
Fixes: 8c8492ca64e79 ("io_uring/net: don't retry connect operation on EPOLLERR")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/3dc89036388d602ebd84c28e5042e457bdfc952b.1752682444.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit fc582cd26e888b0652bc1494f252329453fd3b23
Author: Jens Axboe <axboe@kernel.dk>
Date: Tue Jul 8 11:00:32 2025 -0600
io_uring/msg_ring: ensure io_kiocb freeing is deferred for RCU
syzbot reports that defer/local task_work adding via msg_ring can hit
a request that has been freed:
CPU: 1 UID: 0 PID: 19356 Comm: iou-wrk-19354 Not tainted 6.16.0-rc4-syzkaller-00108-g17bbde2e1716 #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:408 [inline]
print_report+0xd2/0x2b0 mm/kasan/report.c:521
kasan_report+0x118/0x150 mm/kasan/report.c:634
io_req_local_work_add io_uring/io_uring.c:1184 [inline]
__io_req_task_work_add+0x589/0x950 io_uring/io_uring.c:1252
io_msg_remote_post io_uring/msg_ring.c:103 [inline]
io_msg_data_remote io_uring/msg_ring.c:133 [inline]
__io_msg_ring_data+0x820/0xaa0 io_uring/msg_ring.c:151
io_msg_ring_data io_uring/msg_ring.c:173 [inline]
io_msg_ring+0x134/0xa00 io_uring/msg_ring.c:314
__io_issue_sqe+0x17e/0x4b0 io_uring/io_uring.c:1739
io_issue_sqe+0x165/0xfd0 io_uring/io_uring.c:1762
io_wq_submit_work+0x6e9/0xb90 io_uring/io_uring.c:1874
io_worker_handle_work+0x7cd/0x1180 io_uring/io-wq.c:642
io_wq_worker+0x42f/0xeb0 io_uring/io-wq.c:696
ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
which is supposed to be safe with how requests are allocated. But msg
ring requests alloc and free on their own, and hence must defer freeing
to a sane time.
Add an rcu_head and use kfree_rcu() in both spots where requests are
freed. Only the one in io_msg_tw_complete() is strictly required as it
has been visible on the other ring, but use it consistently in the other
spot as well.
This should not cause any other issues outside of KASAN rightfully
complaining about it.
Link: https://lore.kernel.org/io-uring/686cd2ea.a00a0220.338033.0007.GAE@google.com/
Reported-by: syzbot+54cbbfb4db9145d26fc2@syzkaller.appspotmail.com
Cc: stable@vger.kernel.org
Fixes: 0617bb500bfa ("io_uring/msg_ring: improve handling of target CQE posting")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
Conflicts: context differences.
commit 825aea662b492571877b32aeeae13689fd9fbee4
Author: Jens Axboe <axboe@kernel.dk>
Date: Mon Jul 7 16:46:30 2025 -0600
io_uring/rw: cast rw->flags assignment to rwf_t
kernel test robot reports that a recent change of the sqe->rw_flags
field throws a sparse warning on 32-bit archs:
>> io_uring/rw.c:291:19: sparse: sparse: incorrect type in assignment (different base types) @@ expected restricted __kernel_rwf_t [usertype] flags @@ got unsigned int @@
io_uring/rw.c:291:19: sparse: expected restricted __kernel_rwf_t [usertype] flags
io_uring/rw.c:291:19: sparse: got unsigned int
Force cast it to rwf_t to silence that new sparse warning.
Fixes: cf73d9970ea4 ("io_uring: don't use int for ABI")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202507032211.PwSNPNSP-lkp@intel.com/
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
Conflicts: context differences due to missing upstream series
https://lore.kernel.org/all/cover.1743437358.git.asml.silence@gmail.com/.
commit 178b8ff66ff827c41b4fa105e9aabb99a0b5c537
Author: Jens Axboe <axboe@kernel.dk>
Date: Thu Jun 26 12:17:48 2025 -0600
io_uring/kbuf: flag partial buffer mappings
A previous commit aborted mapping more for a non-incremental ring for
bundle peeking, but depending on where in the process this peeking
happened, it would not necessarily prevent a retry by the user. That can
create gaps in the received/read data.
Add struct buf_sel_arg->partial_map, which can pass this information
back. The networking side can then map that to internal state and use it
to gate retry as well.
Since this necessitates a new flag, change io_sr_msg->retry to a
retry_flags member, and store both the retry and partial map condition
in there.
Cc: stable@vger.kernel.org
Fixes: 26ec15e4b0c1 ("io_uring/kbuf: don't truncate end buffer for multiple buffer peeks")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
Conflicts: RHEL does not have commit be7052a4b5a85 ("io_uring/net:
convert to struct iou_vec"). Fix up the patch to apply on our older
version of the code.
commit 9a709b7e98e6fa51600b5f2d24c5068efa6d39de
Author: Jens Axboe <axboe@kernel.dk>
Date: Wed Jun 25 10:17:06 2025 -0600
io_uring/net: mark iov as dynamically allocated even for single segments
A bigger array of vecs could've been allocated, but
io_ring_buffers_peek() still decided to cap the mapped range depending
on how much data was available. Hence don't rely on the segment count
to know if the request should be marked as needing cleanup, always
check upfront if the iov array is different than the fast_iov array.
Fixes: 26ec15e4b0c1 ("io_uring/kbuf: don't truncate end buffer for multiple buffer peeks")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
Conflicts: This patchset pulls in fixes on top of 6.14. This particular
change does not apply cleanly because there were other changes in this
area that are not worth pulling into a fixes patchset. The fix-up is
pretty straight-forward.
commit 5afb4bf9fc62d828647647ec31745083637132e4
Author: Pavel Begunkov <asml.silence@gmail.com>
Date: Tue Jun 24 14:40:33 2025 +0100
io_uring/rsrc: fix folio unpinning
syzbot complains about an unmapping failure:
[ 108.070381][ T14] kernel BUG at mm/gup.c:71!
[ 108.070502][ T14] Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
[ 108.123672][ T14] Hardware name: QEMU KVM Virtual Machine, BIOS edk2-20250221-8.fc42 02/21/2025
[ 108.127458][ T14] Workqueue: iou_exit io_ring_exit_work
[ 108.174205][ T14] Call trace:
[ 108.175649][ T14] sanity_check_pinned_pages+0x7cc/0x7d0 (P)
[ 108.178138][ T14] unpin_user_page+0x80/0x10c
[ 108.180189][ T14] io_release_ubuf+0x84/0xf8
[ 108.182196][ T14] io_free_rsrc_node+0x250/0x57c
[ 108.184345][ T14] io_rsrc_data_free+0x148/0x298
[ 108.186493][ T14] io_sqe_buffers_unregister+0x84/0xa0
[ 108.188991][ T14] io_ring_ctx_free+0x48/0x480
[ 108.191057][ T14] io_ring_exit_work+0x764/0x7d8
[ 108.193207][ T14] process_one_work+0x7e8/0x155c
[ 108.195431][ T14] worker_thread+0x958/0xed8
[ 108.197561][ T14] kthread+0x5fc/0x75c
[ 108.199362][ T14] ret_from_fork+0x10/0x20
We can pin a tail page of a folio, but then io_uring will try to unpin
the head page of the folio. While it should be fine in terms of keeping
the page actually alive, mm folks say it's wrong and triggers a debug
warning. Use unpin_user_folio() instead of unpin_user_page*.
Cc: stable@vger.kernel.org
Debugged-by: David Hildenbrand <david@redhat.com>
Reported-by: syzbot+1d335893772467199ab6@syzkaller.appspotmail.com
Closes: https://lkml.kernel.org/r/683f1551.050a0220.55ceb.0017.GAE@google.com
Fixes: a8edbb424b139 ("io_uring/rsrc: enable multi-hugepage buffer coalescing")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/io-uring/a28b0f87339ac2acf14a645dad1e95bbcbf18acd.1750771718.git.asml.silence@gmail.com/
[axboe: adapt to current tree, massage commit message]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
Conflicts: There are context differences due to upstream commit
ed9f3112a8a8f ("io_uring: cache nodes and mapped buffers").
commit e1c75831f682eef0f68b35723437146ed86070b1
Author: Penglei Jiang <superman.xpt@gmail.com>
Date: Tue Jun 17 09:56:44 2025 -0700
io_uring: fix potential page leak in io_sqe_buffer_register()
If allocation of the 'imu' fails, then the existing pages aren't
unpinned in the error path. This is mostly a theoretical issue,
requiring fault injection to hit.
Move unpin_user_pages() to unified error handling to fix the page leak
issue.
Fixes: d8c2237d0aa9 ("io_uring: add io_pin_pages() helper")
Signed-off-by: Penglei Jiang <superman.xpt@gmail.com>
Link: https://lore.kernel.org/r/20250617165644.79165-1-superman.xpt@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit f2320f1dd6f6f82cb2c7aff23a12bab537bdea89
Author: Jens Axboe <axboe@kernel.dk>
Date: Tue Jun 17 06:43:18 2025 -0600
io_uring/sqpoll: don't put task_struct on tctx setup failure
A recent commit moved the error handling of sqpoll thread and tctx
failures into the thread itself, as part of fixing an issue. However, it
missed that tctx allocation may also fail, and that
io_sq_offload_create() does its own error handling for the task_struct
in that case.
Remove the manual task putting in io_sq_offload_create(), as
io_sq_thread() will notice that the tctx did not get setup and hence it
should put itself and exit.
Reported-by: syzbot+763e12bbf004fb1062e4@syzkaller.appspotmail.com
Fixes: ac0b8b327a56 ("io_uring: fix use-after-free of sq->thread in __io_uring_show_fdinfo()")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 1d27f11bf02b38c431e49a17dee5c10a2b4c2e28
Author: Jens Axboe <axboe@kernel.dk>
Date: Sun Jun 15 08:09:14 2025 -0600
io_uring/rsrc: validate buffer count with offset for cloning
syzbot reports that it can trigger a WARN_ON() for kmalloc() attempt
that's too big:
WARNING: CPU: 0 PID: 6488 at mm/slub.c:5024 __kvmalloc_node_noprof+0x520/0x640 mm/slub.c:5024
Modules linked in:
CPU: 0 UID: 0 PID: 6488 Comm: syz-executor312 Not tainted 6.15.0-rc7-syzkaller-gd7fa1af5b33e #0 PREEMPT
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
pstate: 20400005 (nzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __kvmalloc_node_noprof+0x520/0x640 mm/slub.c:5024
lr : __do_kmalloc_node mm/slub.c:-1 [inline]
lr : __kvmalloc_node_noprof+0x3b4/0x640 mm/slub.c:5012
sp : ffff80009cfd7a90
x29: ffff80009cfd7ac0 x28: ffff0000dd52a120 x27: 0000000000412dc0
x26: 0000000000000178 x25: ffff7000139faf70 x24: 0000000000000000
x23: ffff800082f4cea8 x22: 00000000ffffffff x21: 000000010cd004a8
x20: ffff0000d75816c0 x19: ffff0000dd52a000 x18: 00000000ffffffff
x17: ffff800092f39000 x16: ffff80008adbe9e4 x15: 0000000000000005
x14: 1ffff000139faf1c x13: 0000000000000000 x12: 0000000000000000
x11: ffff7000139faf21 x10: 0000000000000003 x9 : ffff80008f27b938
x8 : 0000000000000002 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 00000000ffffffff x4 : 0000000000400dc0 x3 : 0000000200000000
x2 : 000000010cd004a8 x1 : ffff80008b3ebc40 x0 : 0000000000000001
Call trace:
__kvmalloc_node_noprof+0x520/0x640 mm/slub.c:5024 (P)
kvmalloc_array_node_noprof include/linux/slab.h:1065 [inline]
io_rsrc_data_alloc io_uring/rsrc.c:206 [inline]
io_clone_buffers io_uring/rsrc.c:1178 [inline]
io_register_clone_buffers+0x484/0xa14 io_uring/rsrc.c:1287
__io_uring_register io_uring/register.c:815 [inline]
__do_sys_io_uring_register io_uring/register.c:926 [inline]
__se_sys_io_uring_register io_uring/register.c:903 [inline]
__arm64_sys_io_uring_register+0x42c/0xea8 io_uring/register.c:903
__invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
el0_svc+0x58/0x17c arch/arm64/kernel/entry-common.c:767
el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
which is due to offset + buffer_count being too large. The registration
code checks only the total count of buffers, but given that the indexing
is an array, it should also check offset + count. That can't exceed
IORING_MAX_REG_BUFFERS either, as there's no way to reach buffers beyond
that limit.
There's no issue with registrering a table this large, outside of the
fact that it's pointless to register buffers that cannot be reached, and
that it can trigger this kmalloc() warning for attempting an allocation
that is too large.
Cc: stable@vger.kernel.org
Fixes: b16e920a1909 ("io_uring/rsrc: allow cloning at an offset")
Reported-by: syzbot+cb4bf3cb653be0d25de8@syzkaller.appspotmail.com
Link: https://lore.kernel.org/io-uring/684e77bd.a00a0220.279073.0029.GAE@google.com/
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 26ec15e4b0c1d7b25214d9c0be1d50492e2f006c
Author: Jens Axboe <axboe@kernel.dk>
Date: Fri Jun 13 11:01:49 2025 -0600
io_uring/kbuf: don't truncate end buffer for multiple buffer peeks
If peeking a bunch of buffers, normally io_ring_buffers_peek() will
truncate the end buffer. This isn't optimal as presumably more data will
be arriving later, and hence it's better to stop with the last full
buffer rather than truncate the end buffer.
Cc: stable@vger.kernel.org
Fixes: 35c8711c8fc4 ("io_uring/kbuf: add helpers for getting/peeking multiple buffers")
Reported-by: Christian Mazakas <christian.mazakas@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit c538f400fae22725580842deb2bef546701b64bd
Author: Keith Busch <kbusch@kernel.org>
Date: Wed Jun 11 13:53:43 2025 -0700
io_uring: consistently use rcu semantics with sqpoll thread
The sqpoll thread is dereferenced with rcu read protection in one place,
so it needs to be annotated as an __rcu type, and should consistently
use rcu helpers for access and assignment to make sparse happy.
Since most of the accesses occur under the sqd->lock, we can use
rcu_dereference_protected() without declaring an rcu read section.
Provide a simple helper to get the thread from a locked context.
Fixes: ac0b8b327a5677d ("io_uring: fix use-after-free of sq->thread in __io_uring_show_fdinfo()")
Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20250611205343.1821117-1-kbusch@meta.com
[axboe: fold in fix for register.c]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 2c7f023219966777be0687e15b57689894304cd3
Author: Jens Axboe <axboe@kernel.dk>
Date: Wed May 28 13:45:44 2025 -0600
io_uring/net: only consider msg_inq if larger than 1
Currently retry and general validity of msg_inq is gated on it being
larger than zero, but it's entirely possible for this to be slightly
inaccurate. In particular, if FIN is received, it'll return 1.
Just use larger than 1 as the check. This covers both the FIN case, and
at the same time, it doesn't make much sense to retry a recv immediately
if there's even just a single 1 byte of valid data in the socket.
Leave the SOCK_NONEMPTY flagging when larger than 0 still, as an app may
use that for the final receive.
Cc: stable@vger.kernel.org
Reported-by: Christian Mazakas <christian.mazakas@gmail.com>
Fixes: 7c71a0af81ba ("io_uring/net: improve recv bundles")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 3a08988123c868dbfdd054541b1090fb891fa49e
Author: Jens Axboe <axboe@kernel.dk>
Date: Wed May 21 18:51:49 2025 -0600
io_uring/net: only retry recv bundle for a full transfer
If a shorter than assumed transfer was seen, a partial buffer will have
been filled. For that case it isn't sane to attempt to fill more into
the bundle before posting a completion, as that will cause a gap in
the received data.
Check if the iterator has hit zero and only allow to continue a bundle
operation if that is the case.
Also ensure that for putting finished buffers, only the current transfer
is accounted. Otherwise too many buffers may be put for a short transfer.
Link: https://github.com/axboe/liburing/issues/1409
Cc: stable@vger.kernel.org
Fixes: 7c71a0af81ba ("io_uring/net: improve recv bundles")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit d871198ee431d90f5308d53998c1ba1d5db5619a
Author: Jens Axboe <axboe@kernel.dk>
Date: Tue May 13 15:02:23 2025 -0600
io_uring/fdinfo: grab ctx->uring_lock around io_uring_show_fdinfo()
Not everything requires locking in there, which is why the 'has_lock'
variable exists. But enough does that it's a bit unwieldy to manage.
Wrap the whole thing in a ->uring_lock trylock, and just return
with no output if we fail to grab it. The existing trylock() will
already have greatly diminished utility/output for the failure case.
This fixes an issue with reading the SQE fields, if the ring is being
actively resized at the same time.
Reported-by: Jann Horn <jannh@google.com>
Fixes: 79cfe9e59c2a ("io_uring/register: add IORING_REGISTER_RESIZE_RINGS")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 92835cebab120f8a5f023a26a792a2ac3f816c4f
Author: Gabriel Krisman Bertazi <krisman@suse.de>
Date: Thu May 8 14:12:03 2025 -0400
io_uring/sqpoll: Increase task_work submission batch size
Our QA team reported a 10%-23%, throughput reduction on an io_uring
sqpoll testcase doing IO to a null_blk, that I traced back to a
reduction of the device submission queue depth utilization. It turns out
that, after commit af5d68f8892f ("io_uring/sqpoll: manage task_work
privately"), we capped the number of task_work entries that can be
completed from a single spin of sqpoll to only 8 entries, before the
sqpoll goes around to (potentially) sleep. While this cap doesn't drive
the submission side directly, it impacts the completion behavior, which
affects the number of IO queued by fio per sqpoll cycle on the
submission side, and io_uring ends up seeing less ios per sqpoll cycle.
As a result, block layer plugging is less effective, and we see more
time spent inside the block layer in profilings charts, and increased
submission latency measured by fio.
There are other places that have increased overhead once sqpoll sleeps
more often, such as the sqpoll utilization calculation. But, in this
microbenchmark, those were not representative enough in perf charts, and
their removal didn't yield measurable changes in throughput. The major
overhead comes from the fact we plug less, and less often, when submitting
to the block layer.
My benchmark is:
fio --ioengine=io_uring --direct=1 --iodepth=128 --runtime=300 --bs=4k \
--invalidate=1 --time_based --ramp_time=10 --group_reporting=1 \
--filename=/dev/nullb0 --name=RandomReads-direct-nullb-sqpoll-4k-1 \
--rw=randread --numjobs=1 --sqthread_poll
In one machine, tested on top of Linux 6.15-rc1, we have the following
baseline:
READ: bw=4994MiB/s (5236MB/s), 4994MiB/s-4994MiB/s (5236MB/s-5236MB/s), io=439GiB (471GB), run=90001-90001msec
With this patch:
READ: bw=5762MiB/s (6042MB/s), 5762MiB/s-5762MiB/s (6042MB/s-6042MB/s), io=506GiB (544GB), run=90001-90001msec
which is a 15% improvement in measured bandwidth. The average
submission latency is noticeably lowered too. As measured by
fio:
Baseline:
lat (usec): min=20, max=241, avg=99.81, stdev=3.38
Patched:
lat (usec): min=26, max=226, avg=86.48, stdev=4.82
If we look at blktrace, we can also see the plugging behavior is
improved. In the baseline, we end up limited to plugging 8 requests in
the block layer regardless of the device queue depth size, while after
patching we can drive more io, and we manage to utilize the full device
queue.
In the baseline, after a stabilization phase, an ordinary submission
looks like:
254,0 1 49942 0.016028795 5977 U N [iou-sqp-5976] 7
After patching, I see consistently more requests per unplug.
254,0 1 4996 0.001432872 3145 U N [iou-sqp-3144] 32
Ideally, the cap size would at least be the deep enough to fill the
device queue, but we can't predict that behavior, or assume all IO goes
to a single device, and thus can't guess the ideal batch size. We also
don't want to let the tw run unbounded, though I'm not sure it would
really be a problem. Instead, let's just give it a more sensible value
that will allow for more efficient batching. I've tested with different
cap values, and initially proposed to increase the cap to 1024. Jens
argued it is too big of a bump and I observed that, with 32, I'm no
longer able to observe this bottleneck in any of my machines.
Fixes: af5d68f8892f ("io_uring/sqpoll: manage task_work privately")
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
Link: https://lore.kernel.org/r/20250508181203.3785544-1-krisman@suse.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit b53e523261bf058ea4a518b482222e7a277b186b
Author: Jens Axboe <axboe@kernel.dk>
Date: Sun May 4 08:06:28 2025 -0600
io_uring: always arm linked timeouts prior to issue
There are a few spots where linked timeouts are armed, and not all of
them adhere to the pre-arm, attempt issue, post-arm pattern. This can
be problematic if the linked request returns that it will trigger a
callback later, and does so before the linked timeout is fully armed.
Consolidate all the linked timeout handling into __io_issue_sqe(),
rather than have it spread throughout the various issue entry points.
Cc: stable@vger.kernel.org
Link: https://github.com/axboe/liburing/issues/1390
Reported-by: Chase Hiltz <chase@path.net>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit edd43f4d6f50ec3de55a0c9e9df6348d1da51965
Author: Jens Axboe <axboe@kernel.dk>
Date: Thu Apr 24 10:28:14 2025 -0600
io_uring: fix 'sync' handling of io_fallback_tw()
A previous commit added a 'sync' parameter to io_fallback_tw(), which if
true, means the caller wants to wait on the fallback thread handling it.
But the logic is somewhat messed up, ensure that ctxs are swapped and
flushed appropriately.
Cc: stable@vger.kernel.org
Fixes: dfbe5561ae93 ("io_uring: flush offloaded and delayed task_work on exit")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 6889ae1b4df1579bcdffef023e2ea9a982565dff
Author: Pavel Begunkov <asml.silence@gmail.com>
Date: Thu Mar 27 09:57:27 2025 +0000
io_uring/net: fix io_req_post_cqe abuse by send bundle
[ 114.987980][ T5313] WARNING: CPU: 6 PID: 5313 at io_uring/io_uring.c:872 io_req_post_cqe+0x12e/0x4f0
[ 114.991597][ T5313] RIP: 0010:io_req_post_cqe+0x12e/0x4f0
[ 115.001880][ T5313] Call Trace:
[ 115.002222][ T5313] <TASK>
[ 115.007813][ T5313] io_send+0x4fe/0x10f0
[ 115.009317][ T5313] io_issue_sqe+0x1a6/0x1740
[ 115.012094][ T5313] io_wq_submit_work+0x38b/0xed0
[ 115.013223][ T5313] io_worker_handle_work+0x62a/0x1600
[ 115.013876][ T5313] io_wq_worker+0x34f/0xdf0
As the comment states, io_req_post_cqe() should only be used by
multishot requests, i.e. REQ_F_APOLL_MULTISHOT, which bundled sends are
not. Add a flag signifying whether a request wants to post multiple
CQEs. Eventually REQ_F_APOLL_MULTISHOT should imply the new flag, but
that's left out for simplicity.
Cc: stable@vger.kernel.org
Fixes: a05d1f625c7aa ("io_uring/net: support bundles for send")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/8b611dbb54d1cd47a88681f5d38c84d0c02bc563.1743067183.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 8e3100fcc5cbba03518b8b5c059624aba5c29d50
Author: Caleb Sander Mateos <csander@purestorage.com>
Date: Fri Mar 21 12:48:17 2025 -0600
io_uring/net: only import send_zc buffer once
io_send_zc() guards its call to io_send_zc_import() with if (!done_io)
in an attempt to avoid calling it redundantly on the same req. However,
if the initial non-blocking issue returns -EAGAIN, done_io will stay 0.
This causes the subsequent issue to unnecessarily re-import the buffer.
Add an explicit flag "imported" to io_sr_msg to track if its buffer has
already been imported. Clear the flag in io_send_zc_prep(). Call
io_send_zc_import() and set the flag in io_send_zc() if it is unset.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Fixes: 54cdcca05abd ("io_uring/net: switch io_send() and io_send_zc() to using io_async_msghdr")
Link: https://lore.kernel.org/r/20250321184819.3847386-2-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit c457eed55d80bc06c2c55cd5d7a4646f102db5d4
Author: Pavel Begunkov <asml.silence@gmail.com>
Date: Sun Feb 23 17:22:31 2025 +0000
io_uring: make io_poll_issue() sturdier
io_poll_issue() forwards the call to io_issue_sqe() and thus inherits
some of the handling. That's not particularly failure resistant, as for
example returning an innocently looking IOU_OK from a multishot issue
will lead to severe bugs.
Reimplement io_poll_issue() without io_issue_sqe()'s request completion
logic. Remove extra checks as we know that req->file is already set,
linked timeout are armed, and iopoll is not supported. Also cover it
with warnings for now.
The patch should be useful by itself, but it's also preparing the
codebase for other future clean ups.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/3096d7b1026d9a52426a598bdfc8d9d324555545.1740331076.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit bcf8a0293a019bb0c4aebafdebe9a1e7a923249a
Author: Caleb Sander Mateos <csander@purestorage.com>
Date: Sun Feb 16 19:25:04 2025 -0700
io_uring: introduce type alias for io_tw_state
In preparation for changing how io_tw_state is passed, introduce a type
alias io_tw_token_t for struct io_tw_state *. This allows for changing
the representation in one place, without having to update the many
functions that just forward their struct io_tw_state * argument.
Also add a comment to struct io_tw_state to explain its purpose.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Link: https://lore.kernel.org/r/20250217022511.1150145-1-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 7c71a0af81ba72de9b2c501065e4e718aba9a271
Author: Jens Axboe <axboe@kernel.dk>
Date: Sat Feb 8 10:50:34 2025 -0700
io_uring/net: improve recv bundles
Current recv bundles are only supported for multishot receives, and
additionally they also always post at least 2 CQEs if more data is
available than what a buffer will hold. This happens because the initial
bundle recv will do a single buffer, and then do the rest of what is in
the socket as a followup receive. As shown in a test program, if 1k
buffers are available and 32k is available to receive in the socket,
you'd get the following completions:
bundle=1, mshot=0
cqe res 1024
cqe res 1024
[...]
cqe res 1024
bundle=1, mshot=1
cqe res 1024
cqe res 31744
where bundle=1 && mshot=0 will post 32 1k completions, and bundle=1 &&
mshot=1 will post a 1k completion and then a 31k completion.
To support bundle recv without multishot, it's possible to simply retry
the recv immediately and post a single completion, rather than split it
into two completions. With the below patch, the same test looks as
follows:
bundle=1, mshot=0
cqe res 32768
bundle=1, mshot=1
cqe res 32768
where mshot=0 works fine for bundles, and both of them post just a
single 32k completion rather than split it into separate completions.
Posting fewer completions is always a nice win, and not needing
multishot for proper bundle efficiency is nice for cases that can't
necessarily use multishot.
Reported-by: Norman Maurer <norman_maurer@apple.com>
Link: https://lore.kernel.org/r/184f9f92-a682-4205-a15d-89e18f664502@kernel.dk
Fixes: 2f9c9515bdfd ("io_uring/net: support bundles for recv")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
Conflicts: RHEL does not have commit 6ee78354eaa60 ("io_uring/io-wq:
cache work->flags in variable"), and I didn't pull it in as it was
part of a larger patch series.
commit 486ba4d84d62e92716cd395c4b1612b8ce70a257
Author: Max Kellermann <max.kellermann@ionos.com>
Date: Tue Jan 28 14:39:24 2025 +0100
io_uring/io-wq: do not use bogus hash value
Previously, the `hash` variable was initialized with `-1` and only
updated by io_get_next_work() if the current work was hashed. Commit
60cf46ae60 ("io-wq: hash dependent work") changed this to always
call io_get_work_hash() even if the work was not hashed. This caused
the `hash != -1U` check to always be true, adding some overhead for
the `hash->wait` code.
This patch fixes the regression by checking the `IO_WQ_WORK_HASHED`
flag.
Perf diff for a flood of `IORING_OP_NOP` with `IOSQE_ASYNC`:
38.55% -1.57% [kernel.kallsyms] [k] queued_spin_lock_slowpath
6.86% -0.72% [kernel.kallsyms] [k] io_worker_handle_work
0.10% +0.67% [kernel.kallsyms] [k] put_prev_entity
1.96% +0.59% [kernel.kallsyms] [k] io_nop_prep
3.31% -0.51% [kernel.kallsyms] [k] try_to_wake_up
7.18% -0.47% [kernel.kallsyms] [k] io_wq_free_work
Fixes: 60cf46ae60 ("io-wq: hash dependent work")
Cc: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
Link: https://lore.kernel.org/r/20250128133927.3989681-6-max.kellermann@ionos.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 67c007d6c12da3e456c005083696c20d4498ae72
Author: Pavel Begunkov <asml.silence@gmail.com>
Date: Sat Mar 22 11:47:27 2025 +0000
io_uring/net: fix sendzc double notif flush
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 5823 at lib/refcount.c:28 refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28
RIP: 0010:refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28
Call Trace:
<TASK>
io_notif_flush io_uring/notif.h:40 [inline]
io_send_zc_cleanup+0x121/0x170 io_uring/net.c:1222
io_clean_op+0x58c/0x9a0 io_uring/io_uring.c:406
io_free_batch_list io_uring/io_uring.c:1429 [inline]
__io_submit_flush_completions+0xc16/0xd20 io_uring/io_uring.c:1470
io_submit_flush_completions io_uring/io_uring.h:159 [inline]
Before the blamed commit, sendzc relied on io_req_msg_cleanup() to clear
REQ_F_NEED_CLEANUP, so after the following snippet the request will
never hit the core io_uring cleanup path.
io_notif_flush();
io_req_msg_cleanup();
The easiest fix is to null the notification. io_send_zc_cleanup() can
still be called after, but it's tolerated.
Reported-by: syzbot+cf285a028ffba71b2ef5@syzkaller.appspotmail.com
Tested-by: syzbot+cf285a028ffba71b2ef5@syzkaller.appspotmail.com
Fixes: cc34d8330e036 ("io_uring/net: don't clear REQ_F_NEED_CLEANUP unconditionally")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e1306007458b8891c88c4f20c966a17595f766b0.1742643795.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit cc34d8330e036b6bffa88db9ea537bae6b03948f
Author: Jens Axboe <axboe@kernel.dk>
Date: Thu Mar 20 12:25:12 2025 -0600
io_uring/net: don't clear REQ_F_NEED_CLEANUP unconditionally
io_req_msg_cleanup() relies on the fact that io_netmsg_recycle() will
always fully recycle, but that may not be the case if the msg cache
was already full. To ensure that normal cleanup always gets run,
let io_netmsg_recycle() deal with clearing the relevant cleanup flags,
as it knows exactly when that should be done.
Cc: stable@vger.kernel.org
Reported-by: David Wei <dw@davidwei.uk>
Fixes: 75191341785e ("io_uring/net: add iovec recycling")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit bcb0fda3c2da9fe4721d3e73d80e778c038e7d27
Author: Jens Axboe <axboe@kernel.dk>
Date: Wed Mar 5 14:03:34 2025 -0700
io_uring/rw: ensure reissue path is correctly handled for IOPOLL
The IOPOLL path posts CQEs when the io_kiocb is marked as completed,
so it cannot rely on the usual retry that non-IOPOLL requests do for
read/write requests.
If -EAGAIN is received and the request should be retried, go through
the normal completion path and let the normal flush logic catch it and
reissue it, like what is done for !IOPOLL reads or writes.
Fixes: d803d123948f ("io_uring/rw: handle -EAGAIN retry at IO completion time")
Reported-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/io-uring/2b43ccfa-644d-4a09-8f8f-39ad71810f41@oracle.com/
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit fb3331f53e3cb1f1505f918f4f33bb0a3a231e4f
Author: Caleb Sander Mateos <csander@purestorage.com>
Date: Tue Feb 18 20:34:43 2025 -0700
io_uring/rsrc: remove unused constants
IO_NODE_ALLOC_CACHE_MAX has been unused since commit fbbb8e991d86
("io_uring/rsrc: get rid of io_rsrc_node allocation cache") removed the
rsrc_node_cache.
IO_RSRC_TAG_TABLE_SHIFT and IO_RSRC_TAG_TABLE_MASK have been unused
since commit 7029acd8a950 ("io_uring/rsrc: get rid of per-ring
io_rsrc_node list") removed the separate tag table for registered nodes.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Li Zetao <lizetao1@huawei.com>
Link: https://lore.kernel.org/r/20250219033444.2020136-1-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 1fc61eeefe10d9996d2b875214d89f0909d03417
Author: Jens Axboe <axboe@kernel.dk>
Date: Tue Feb 18 16:47:40 2025 -0700
io_uring: fix spelling error in uapi io_uring.h
This is obviously not that important, but when changes are synced back
from the kernel to liburing, the codespell CI ends up erroring because
of this misspelling. Let's just correct it and avoid this biting us
again on an import.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 13918315c5dc5a515926c8799042ea6885c2b734
Author: Uday Shankar <ushankar@purestorage.com>
Date: Sat Feb 8 13:42:13 2025 -0700
io-wq: backoff when retrying worker creation
When io_uring submission goes async for the first time on a given task,
we'll try to create a worker thread to handle the submission. Creating
this worker thread can fail due to various transient conditions, such as
an outstanding signal in the forking thread, so we have retry logic with
a limit of 3 retries. However, this retry logic appears to be too
aggressive/fast - we've observed a thread blowing through the retry
limit while having the same outstanding signal the whole time. Here's an
excerpt of some tracing that demonstrates the issue:
First, signal 26 is generated for the process. It ends up getting routed
to thread 92942.
0) cbd-92284 /* signal_generate: sig=26 errno=0 code=-2 comm=psblkdASD pid=92934 grp=1 res=0 */
This causes create_io_thread in the signalled thread to fail with
ERESTARTNOINTR, and thus a retry is queued.
13) task_th-92942 /* io_uring_queue_async_work: ring 000000007325c9ae, request 0000000080c96d8e, user_data 0x0, opcode URING_CMD, flags 0x8240001, normal queue, work 000000006e96dd3f */
13) task_th-92942 io_wq_enqueue() {
13) task_th-92942 _raw_spin_lock();
13) task_th-92942 io_wq_activate_free_worker();
13) task_th-92942 _raw_spin_lock();
13) task_th-92942 create_io_worker() {
13) task_th-92942 __kmalloc_cache_noprof();
13) task_th-92942 __init_swait_queue_head();
13) task_th-92942 kprobe_ftrace_handler() {
13) task_th-92942 get_kprobe();
13) task_th-92942 aggr_pre_handler() {
13) task_th-92942 pre_handler_kretprobe();
13) task_th-92942 /* create_enter: (create_io_thread+0x0/0x50) fn=0xffffffff8172c0e0 arg=0xffff888996bb69c0 node=-1 */
13) task_th-92942 } /* aggr_pre_handler */
...
13) task_th-92942 } /* copy_process */
13) task_th-92942 } /* create_io_thread */
13) task_th-92942 kretprobe_rethook_handler() {
13) task_th-92942 /* create_exit: (create_io_worker+0x8a/0x1a0 <- create_io_thread) arg1=0xfffffffffffffdff */
13) task_th-92942 } /* kretprobe_rethook_handler */
13) task_th-92942 queue_work_on() {
...
The CPU is then handed to a kworker to process the queued retry:
------------------------------------------
13) task_th-92942 => kworker-54154
------------------------------------------
13) kworker-54154 io_workqueue_create() {
13) kworker-54154 io_queue_worker_create() {
13) kworker-54154 task_work_add() {
13) kworker-54154 wake_up_state() {
13) kworker-54154 try_to_wake_up() {
13) kworker-54154 _raw_spin_lock_irqsave();
13) kworker-54154 _raw_spin_unlock_irqrestore();
13) kworker-54154 } /* try_to_wake_up */
13) kworker-54154 } /* wake_up_state */
13) kworker-54154 kick_process();
13) kworker-54154 } /* task_work_add */
13) kworker-54154 } /* io_queue_worker_create */
13) kworker-54154 } /* io_workqueue_create */
And then we immediately switch back to the original task to try creating
a worker again. This fails, because the original task still hasn't
handled its signal.
-----------------------------------------
13) kworker-54154 => task_th-92942
------------------------------------------
13) task_th-92942 create_worker_cont() {
13) task_th-92942 kprobe_ftrace_handler() {
13) task_th-92942 get_kprobe();
13) task_th-92942 aggr_pre_handler() {
13) task_th-92942 pre_handler_kretprobe();
13) task_th-92942 /* create_enter: (create_io_thread+0x0/0x50) fn=0xffffffff8172c0e0 arg=0xffff888996bb69c0 node=-1 */
13) task_th-92942 } /* aggr_pre_handler */
13) task_th-92942 } /* kprobe_ftrace_handler */
13) task_th-92942 create_io_thread() {
13) task_th-92942 copy_process() {
13) task_th-92942 task_active_pid_ns();
13) task_th-92942 _raw_spin_lock_irq();
13) task_th-92942 recalc_sigpending();
13) task_th-92942 _raw_spin_lock_irq();
13) task_th-92942 } /* copy_process */
13) task_th-92942 } /* create_io_thread */
13) task_th-92942 kretprobe_rethook_handler() {
13) task_th-92942 /* create_exit: (create_worker_cont+0x35/0x1b0 <- create_io_thread) arg1=0xfffffffffffffdff */
13) task_th-92942 } /* kretprobe_rethook_handler */
13) task_th-92942 io_worker_release();
13) task_th-92942 queue_work_on() {
13) task_th-92942 clear_pending_if_disabled();
13) task_th-92942 __queue_work() {
13) task_th-92942 } /* __queue_work */
13) task_th-92942 } /* queue_work_on */
13) task_th-92942 } /* create_worker_cont */
The pattern repeats another couple times until we blow through the retry
counter, at which point we give up. All outstanding work is canceled,
and the io_uring command which triggered all this is failed with
ECANCELED:
13) task_th-92942 io_acct_cancel_pending_work() {
...
13) task_th-92942 /* io_uring_complete: ring 000000007325c9ae, req 0000000080c96d8e, user_data 0x0, result -125, cflags 0x0 extra1 0 extra2 0 */
Finally, the task gets around to processing its outstanding signal 26,
but it's too late.
13) task_th-92942 /* signal_deliver: sig=26 errno=0 code=-2 sa_handler=59566a0 sa_flags=14000000 */
Try to address this issue by adding a small scaling delay when retrying
worker creation. This should give the forking thread time to handle its
signal in the above case. This isn't a particularly satisfying solution,
as sufficiently paradoxical scheduling would still have us hitting the
same issue, and I'm open to suggestions for something better. But this
is likely to prevent this (already rare) issue from hitting in practice.
Signed-off-by: Uday Shankar <ushankar@purestorage.com>
Link: https://lore.kernel.org/r/20250208-wq_retry-v2-1-4f6f5041d303@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
Conflicts: Patch application order is different in RHEL. We already
have commit eaf72f7b414f5 ("io_uring/uring_cmd: cleanup struct
io_uring_cmd_data layout"), which changes context.
commit d6211ebbdaa541af197b50b8dd8f22642ce0b87f
Author: Jens Axboe <axboe@kernel.dk>
Date: Thu Feb 13 08:24:23 2025 -0700
io_uring/uring_cmd: unconditionally copy SQEs at prep time
This isn't generally necessary, but conditions have been observed where
SQE data is accessed from the original SQE after prep has been done and
outside of the initial issue. Opcode prep handlers must ensure that any
SQE related data is stable beyond the prep phase, but uring_cmd is a bit
special in how it handles the SQE which makes it susceptible to reading
stale data. If the application has reused the SQE before the original
completes, then that can lead to data corruption.
Down the line we can relax this again once uring_cmd has been sanitized
a bit, and avoid unnecessarily copying the SQE.
Fixes: 5eff57fa9f3a ("io_uring/uring_cmd: defer SQE copying until it's needed")
Reported-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Li Zetao <lizetao1@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 2b4fc4cd43f28e9e39179c8702e6ee821258584d
Author: Jens Axboe <axboe@kernel.dk>
Date: Wed Feb 12 15:52:54 2025 -0700
io_uring/waitid: setup async data in the prep handler
This is the idiomatic way that opcodes should setup their async data,
so that it's always valid inside ->issue() without issue needing to
do that.
Fixes: f31ecf671ddc4 ("io_uring: add IORING_OP_WAITID support")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 0edf1283a9d1419a2095b4fcdd95c11ac00a191c
Author: Jens Axboe <axboe@kernel.dk>
Date: Wed Feb 12 14:05:11 2025 -0700
io_uring/uring_cmd: remove dead req_has_async_data() check
Any uring_cmd always has async data allocated now, there's no reason to
check and clear a cached copy of the SQE.
Fixes: d10f19dff56e ("io_uring/uring_cmd: switch to always allocating async data")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit e663da62ba8672aaa66843f1af8b20e3bb1a0515
Author: Caleb Sander Mateos <csander@purestorage.com>
Date: Wed Feb 12 13:45:46 2025 -0700
io_uring/uring_cmd: switch sqe to async_data on EAGAIN
5eff57fa9f3a ("io_uring/uring_cmd: defer SQE copying until it's needed")
moved the unconditional memcpy() of the uring_cmd SQE to async_data
to 2 cases when the request goes async:
- If REQ_F_FORCE_ASYNC is set to force the initial issue to go async
- If ->uring_cmd() returns -EAGAIN in the initial non-blocking issue
Unlike the REQ_F_FORCE_ASYNC case, in the EAGAIN case, io_uring_cmd()
copies the SQE to async_data but neglects to update the io_uring_cmd's
sqe field to point to async_data. As a result, sqe still points to the
slot in the userspace-mapped SQ. At the end of io_submit_sqes(), the
kernel advances the SQ head index, allowing userspace to reuse the slot
for a new SQE. If userspace reuses the slot before the io_uring worker
reissues the original SQE, the io_uring_cmd's SQE will be corrupted.
Introduce a helper io_uring_cmd_cache_sqes() to copy the original SQE to
the io_uring_cmd's async_data and point sqe there. Use it for both the
REQ_F_FORCE_ASYNC and EAGAIN cases. This ensures the uring_cmd doesn't
read from the SQ slot after it has been returned to userspace.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Fixes: 5eff57fa9f3a ("io_uring/uring_cmd: defer SQE copying until it's needed")
Link: https://lore.kernel.org/r/20250212204546.3751645-3-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 34cae91215c6f65bed2a124fb9283da6ec0b8dd9
Author: Caleb Sander Mateos <csander@purestorage.com>
Date: Wed Feb 12 13:45:45 2025 -0700
io_uring/uring_cmd: don't assume io_uring_cmd_data layout
eaf72f7b414f ("io_uring/uring_cmd: cleanup struct io_uring_cmd_data
layout") removed most of the places assuming struct io_uring_cmd_data
has sqes as its first field. However, the EAGAIN case in io_uring_cmd()
still compares ioucmd->sqe to the struct io_uring_cmd_data pointer using
a void * cast. Since fa3595523d72 ("io_uring: get rid of alloc cache
init_once handling"), sqes is no longer io_uring_cmd_data's first field.
As a result, the pointers will always compare unequal and memcpy() may
be called with the same source and destination.
Replace the incorrect void * cast with the address of the sqes field.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Fixes: eaf72f7b414f ("io_uring/uring_cmd: cleanup struct io_uring_cmd_data layout")
Link: https://lore.kernel.org/r/20250212204546.3751645-2-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 8802766324e1f5d414a81ac43365c20142e85603
Author: Pavel Begunkov <asml.silence@gmail.com>
Date: Wed Feb 12 13:46:46 2025 +0000
io_uring/kbuf: reallocate buf lists on upgrade
IORING_REGISTER_PBUF_RING can reuse an old struct io_buffer_list if it
was created for legacy selected buffer and has been emptied. It violates
the requirement that most of the field should stay stable after publish.
Always reallocate it instead.
Cc: stable@vger.kernel.org
Reported-by: Pumpkin Chang <pumpkin@devco.re>
Fixes: 2fcabce2d7d34 ("io_uring: disallow mixed provided buffer group registrations")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 06521ac0485effdcc9c792cb0b40ed8e6f2f5fb8
Author: Pavel Begunkov <asml.silence@gmail.com>
Date: Wed Feb 12 13:33:24 2025 +0000
io_uring/waitid: don't abuse io_tw_state
struct io_tw_state is managed by core io_uring, and opcode handling code
must never try to cheat and create their own instances, it's plain
incorrect.
io_waitid_complete() attempts exactly that outside of the task work
context, and even though the ring is locked, there would be no one to
reap the requests from the defer completion list. It only works now
because luckily it's called before io_uring_try_cancel_uring_cmd(),
which flushes completions.
Fixes: f31ecf671ddc4 ("io_uring: add IORING_OP_WAITID support")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 8c8492ca64e79c6e0f433e8c9d2bcbd039ef83d0
Author: Jens Axboe <axboe@kernel.dk>
Date: Thu Jan 30 08:40:29 2025 -0700
io_uring/net: don't retry connect operation on EPOLLERR
If a socket is shutdown before the connection completes, POLLERR is set
in the poll mask. However, connect ignores this as it doesn't know, and
attempts the connection again. This may lead to a bogus -ETIMEDOUT
result, where it should have noticed the POLLERR and just returned
-ECONNRESET instead.
Have the poll logic check for whether or not POLLERR is set in the mask,
and if so, mark the request as failed. Then connect can appropriately
fail the request rather than retry it.
Reported-by: Sergey Galas <ssgalas@cloud.ru>
Cc: stable@vger.kernel.org
Link: https://github.com/axboe/liburing/discussions/1335
Fixes: 3fb1bd688172 ("io_uring/net: handle -EINPROGRESS correct for IORING_OP_CONNECT")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 0d124578fed92cadeaca47d734da782beacdc1a7
Author: Pavel Begunkov <asml.silence@gmail.com>
Date: Tue Jan 28 20:56:15 2025 +0000
io_uring: remove !KASAN guards from cache free
Test setups (with KASAN) will avoid !KASAN sections, and so it's not
testing paths that would be exercised otherwise. That's bad as to be
sure that your code works you now have to specifically test both KASAN
and !KASAN configs.
Remove !CONFIG_KASAN guards from io_netmsg_cache_free() and
io_rw_cache_free(). The free functions should always be getting valid
entries, and even though for KASAN iovecs should already be cleared,
that's better than skipping the chunks completely.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Link: https://lore.kernel.org/r/d6078a51c7137a243f9d00849bc3daa660873209.1738087204.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit a23ad06bfee5e51cd9e51aebf11401e7b4b5d00a
Author: Jens Axboe <axboe@kernel.dk>
Date: Fri Jan 24 14:32:25 2025 -0700
io_uring/register: use atomic_read/write for sq_flags migration
A previous commit changed all of the migration from the old to the new
ring for resizing to use READ/WRITE_ONCE. However, ->sq_flags is an
atomic_t, and while most archs won't complain on this, some will indeed
flag this:
io_uring/register.c:554:9: sparse: sparse: cast to non-scalar
io_uring/register.c:554:9: sparse: sparse: cast from non-scalar
Just use atomic_set/atomic_read for handling this case.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202501242000.A2sKqaCL-lkp@intel.com/
Fixes: 2c5aae129f42 ("io_uring/register: document io_register_resize_rings() shared mem usage")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-105612
commit 5e0e02f0d7e52cfc8b1adfc778dd02181d8b47b4
Author: Jens Axboe <axboe@kernel.dk>
Date: Wed Jan 15 09:05:15 2025 -0700
futex: Pass in task to futex_queue()
futex_queue() -> __futex_queue() uses 'current' as the task to store in
the struct futex_q->task field. This is fine for synchronous usage of
the futex infrastructure, but it's not always correct when used by
io_uring where the task doing the initial futex_queue() might not be
available later on. This doesn't lead to any issues currently, as the
io_uring side doesn't support PI futexes, but it does leave a
potentially dangling pointer which is never a good idea.
Have futex_queue() take a task_struct argument, and have the regular
callers pass in 'current' for that. Meanwhile io_uring can just pass in
NULL, as the task should never be used off that path. In theory
req->tctx->task could be used here, but there's no point populating it
with a task field that will never be used anyway.
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/22484a23-542c-4003-b721-400688a0d055@kernel.dk
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Jeff Moyer