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When doing cancellation, we use a parameter to indicate where it's from
do_exit or exec. So a boolean value is good enough for this, remove the
struct files* as it is not necessary.
Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
[axboe: fixup io_uring_files_cancel for !CONFIG_IO_URING]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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As submission references are gone, there is only one initial reference
left. Instead of actually doing atomic refcounting, add a flag
indicating whether we're going to take more refs or doing any other sync
magic. The flag should be set before the request may get used in
parallel.
Together with the previous patch it saves 2 refcount atomics per request
for IOPOLL and IRQ completions, and 1 atomic per req for inline
completions, with some exceptions. In particular, currently, there are
three cases, when the refcounting have to be enabled:
- Polling, including apoll. Because double poll entries takes a ref.
Might get relaxed in the near future.
- Link timeouts, enabled for both, the timeout and the request it's
bound to, because they work in-parallel and we need to synchronise
to cancel one of them on completion.
- When a request gets in io-wq, because it doesn't hold uring_lock and
we need guarantees of submission references.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/8b204b6c5f6643062270a1913d6d3a7f8f795fd9.1628705069.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Requests are by default given with two references, submission and
completion. Completion references are straightforward, they represent
request ownership and are put when a request is completed or so.
Submission references are a bit more trickier. They're needed when
io_issue_sqe() followed deep into the submission stack (e.g. in fs,
block, drivers, etc.), request may have given away for concurrent
execution or already completed, and the code unwinding back to
io_issue_sqe() may be accessing some pieces of our requests, e.g.
file or iov.
Now, we prevent such async/in-depth completions by pushing requests
through task_work. Punting to io-wq is also done through task_works,
apart from a couple of cases with a pretty well known context. So,
there're two cases:
1) io_issue_sqe() from the task context and protected by ->uring_lock.
Either requests return back to io_uring or handed to task_work, which
won't be executed because we're currently controlling that task. So,
we can be sure that requests are staying alive all the time and we don't
need submission references to pin them.
2) io_issue_sqe() from io-wq, which doesn't hold the mutex. The role of
submission reference is played by io-wq reference, which is put by
io_wq_submit_work(). Hence, it should be fine.
Considering that, we can carefully kill the submission reference.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6b68f1c763229a590f2a27148aee77767a8d7750.1628705069.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Soon, we won't need to put several references at once, remove
req_ref_sub_and_test() and @nr argument from io_put_req_deferred(),
and put the rest of the references by hand.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1868c7554108bff9194fb5757e77be23fadf7fc0.1628705069.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Move all request refcount helpers to avoid forward declarations in the
future.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/89fd36f6f3fe5b733dfe4546c24725eee40df605.1628705069.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We have no hard/soft IRQ users of this lock left, remove any IRQ
disabling/saving and restoring when grabbing this lock.
This is straight forward with no users entering with IRQs disabled
anymore, the only thing to look out for is the waitqueue poll head
lock which nests inside the completion lock. That needs IRQs disabled,
and hence we have to do that now instead of relying on the outer lock
doing so.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This is in preparation to making the completion lock work outside of
hard/soft IRQ context.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This is in preparation to making the completion lock work outside of
hard/soft IRQ context.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This is in preparation to making the completion lock work outside of
hard/soft IRQ context.
Add a timeout_lock to handle the ordering of timeout completions or
cancelations with the timeouts actually triggering.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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For requests with non-fixed files, instead of grabbing just one
reference, we get by the number of left requests, so the following
requests using the same file can take it without atomics.
However, it's not all win. If there is one request in the middle
not using files or having a fixed file, we'll need to put back the left
references. Even worse if an application submits requests dealing with
different files, it will do a put for each new request, so doubling the
number of atomics needed. Also, even if not used, it's still takes some
cycles in the submission path.
If a file used many times, it rather makes sense to pre-register it, if
not, we may fall in the described pitfall. So, this optimisation is a
matter of use case. Go with the simpliest code-wise way, remove it.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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After recent fixes, tctx_task_work() always does proper spinlocking
before looking into ->task_list, so now we don't need atomics for
->task_state, replace it with non-atomic task_running using the critical
section.
Tide it up, combine two separate block with spinlocking, and always try
to splice in there, so we do less locking when new requests are arriving
during the function execution.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
[axboe: fix missing ->task_running reset on task_work_add() failure]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Inline io_poll_remove_waitqs() into its only user and clean it up.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/2f1a91a19ffcd591531dc4c61e2f11c64a2d6a6d.1628536684.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Unlike __io_cqring_overflow_flush(), nobody does forced flushing with
io_cqring_overflow_flush(), so removed the argument from it.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/7594f869ca41b7cfb5a35a3c7c2d402242834e9e.1628536684.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Inline struct io_comp_state into struct io_submit_state. They are
already coupled tightly, together with mixed responsibilities it
only brings confusion having them separately.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e55bba77426b399e3a2e54e3c6c267c6a0fc4b57.1628536684.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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req->compl.list is used to cache freed requests, and so can't overlap in
time with req->inflight_entry. So, use inflight_entry to link requests
and remove compl.list.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e430e79d22d70a190d718831bda7bfed1daf8976.1628536684.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We don't use @tsk argument of io_req_cache_free(), remove it.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6a28b4a58ee0aaf0db98e2179b9c9f06f9b0cca1.1628536684.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Don't kfree requests in __io_free_req() but put them back into the
internal request cache. That makes allocations more sustainable and will
be used for refcounting optimisations.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/9f4950fbe7771c8d41799366d0a3a08ac3040236.1628536684.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Move io_fallback_req_func() to kill yet another forward declaration.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/d0a8f9d9a0057ed761d6237167d51c9378798d2d.1628536684.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We cache all the reference to task + tctx, so if io_put_task() is
called by the corresponding task itself, we can save on atomics and
return the refs right back into the cache.
It's beneficial for all inline completions, and also iopolling, when
polling and submissions are done by the same task, including
SQPOLL|IOPOLL.
Note: io_uring_cancel_generic() can return refs to the cache as well,
so those should be flushed in the loop for tctx_inflight() to work
right.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6fe9646b3cb70e46aca1f58426776e368c8926b3.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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In case of on-exec io_uring cancellations, tasks already wait for all
submitted requests to get completed/cancelled, so we don't need to check
for ->in_execve separately.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/be8707049f10df9d20ca03dc4ca3316239b5e8e0.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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IO_IOPOLL_BATCH is not used, delete it.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/b2bdf19dbee2c9fc8865bbab9412135a14e24a64.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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If io_ring_exit_work() can't get it done in 5 minutes, something is
going very wrong, don't keep spinning at HZ / 20 rate, it doesn't help
and it may take much of CPU time if there is a lot of workers stuck as
such.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/9e2d1ca81d569f6bc628af1a42ff6663bff7ce9c.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Move IORING_SETUP_IOPOLL check into __io_openat_prep(), so both openat
and openat2 reuse it.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/9a73ce83e4ee60d011180ef177eecef8e87ff2a2.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Inline io_free_req_deferred(), there is no reason to keep it separated.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/ce04b7180d4eac0d69dd00677b227eefe80c2cc5.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Move the function together with io_rsrc_node_ref_zero() in the source
file as it is to get rid of forward declarations.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/4d81f6f833e7d017860b24463a9a68b14a8a5ed2.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Move the function in the source file as it is to get rid of forward
declarations.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/33d917d69e4206557c75a5b98fe22bcdf77ce47d.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Refactor __io_uring_register() by extracting a helper responsible for
ctx queisce. Looks better and will make it easier to add more
optimisations.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/0339e0027504176be09237eefa7945bf9a6f153d.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Turns out we always init struct io_wait_queue in io_cqring_wait(), even
if it's not used after, i.e. there are already enough of CQEs. And often
it's exactly what happens, for instance, requests may have been
completed inline, or in case of io_uring_enter(submit=N, wait=1).
It shows up in my profiler, so optimise it by delaying the struct init.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6f1b81c60b947d165583dc333947869c3d85d037.1628471125.git.asml.silence@gmail.com
[axboe: fixed up for new cqring wait]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Add more annotations for submission path functions holding ->uring_lock.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/128ec4185e26fbd661dd3a424aa66108ee8ff951.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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IOPOLL users should care more about getting completions for requests
they submitted, but not in "device did/completed something". Currently,
io_do_iopoll() may return a positive number, which will instruct
io_iopoll_check() to break the loop and end the syscall, even if there
is not enough CQEs or none at all.
Don't return positive numbers, so io_iopoll_check() exits only when it
gets an actual error, need reschedule or got enough CQEs.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/641a88f751623b6758303b3171f0a4141f06726e.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Replace the main if of io_flush_cached_reqs() with inverted condition +
goto, so all the cases are handled in the same way. And also extract
io_preinit_req() to make it cleaner and easier to refer to.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1abcba1f7b55dc53bf1dbe95036e345ffb1d5b01.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We prefer nornal task_works even if it would fail requests inside. Kill
a PF_EXITING check in io_req_task_work_add(), task_work_add() handles
well dying tasks, i.e. return error when can't enqueue due to late
stages of do_exit().
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/fc14297e8441cd8f5d1743a2488cf0df09bf48ac.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Move io-wq callbacks closer to each other, so it's easier to work with
them, and rename io_free_work() into io_wq_free_work() for consistency.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/851bbc7f0f86f206d8c1333efee8bcb9c26e419f.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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If we use fixed files, we can be sure (almost) that REQ_F_ISREG is set.
However, for non-reg files io_prep_rw() still will look into inode to
double check, and that's expensive and can be avoided.
The only caveat is that it only currently works with 64+ bit
architectures, see FFS_ISREG, so we should consider that.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/0a62780c491ca2522cd52db4ae3f16e03aafed0f.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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io_file_supports_async() checks whether a file supports nowait
operations, so "async" in the name is misleading. Rename it.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/33d55b5ce43aa1884c637c1957f1e30d30dc3bec.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Optimise io_file_get() with registered files, which is in a hot path,
by inlining parts of the function. Saves a function call, and
inefficiencies of passing arguments, e.g. evaluating
(sqe_flags & IOSQE_FIXED_FILE).
It couldn't have been done before as compilers were refusing to inline
it because of the function size.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/52115cd6ce28f33bd0923149c0e6cb611084a0b1.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Instead of hand-coded two-level tables for registered files, allocate
them with kvmalloc(). In many cases small enough tables are enough, and
so can be kmalloc()'ed removing an extra memory load and a bunch of bit
logic instructions from the hot path. If the table is larger, we trade
off all the pros with a TLB-assisted memory lookup.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/280421d3b48775dabab773006bb5588c7b2dabc0.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Currently we only wake the first waiter, even if we have enough entries
posted to satisfy multiple waiters. Improve that situation so that
every waiter knows how much the CQ tail has to advance before they can
be safely woken up.
With this change, if we have N waiters each asking for 1 event and we get
4 completions, then we wake up 4 waiters. If we have N waiters asking
for 2 completions and we get 4 completions, then we wake up the first
two. Previously, only the first waiter would've been woken up.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We currently check for ret != 0 to indicate error, but '1' is a valid
return and just indicates that the allocation succeeded with a wrap.
Correct the check to be for < 0, like it was before the xarray
conversion.
Cc: stable@vger.kernel.org
Fixes: 61cf93700fe6 ("io_uring: Convert personality_idr to XArray")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Pin ring in io_fallback_req_func() by briefly elevating ctx->refs in
case any task_work handler touches ctx after releasing a request.
Fixes: 9011bf9a13e3b ("io_uring: fix stuck fallback reqs")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/833a494713d235ec144284a9bbfe418df4f6b61c.1629235576.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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If an SQPOLL based ring is newly created and an application issues an
io_uring_enter(2) system call on it, then we can return a spurious
-EOWNERDEAD error. This happens because there's nothing to submit, and
if the caller doesn't specify any other action, the initial error
assignment of -EOWNERDEAD never gets overwritten. This causes us to
return it directly, even if it isn't valid.
Move the error assignment into the actual failure case instead.
Cc: stable@vger.kernel.org
Fixes: d9d05217cb69 ("io_uring: stop SQPOLL submit on creator's death")
Reported-by: Sherlock Holo sherlockya@gmail.com
Link: https://github.com/axboe/liburing/issues/413
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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__io_rsrc_put_work() might need ->uring_lock, so nobody should wait for
rsrc nodes holding the mutex. However, that's exactly what
io_ring_ctx_free() does with io_wait_rsrc_data().
Split it into rsrc wait + dealloc, and move the first one out of the
lock.
Cc: stable@vger.kernel.org
Fixes: b60c8dce33895 ("io_uring: preparation for rsrc tagging")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/0130c5c2693468173ec1afab714e0885d2c9c363.1628559783.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Ammar reports that he's seeing a lockdep splat on running test/rsrc_tags
from the regression suite:
======================================================
WARNING: possible circular locking dependency detected
5.14.0-rc3-bluetea-test-00249-gc7d102232649 #5 Tainted: G OE
------------------------------------------------------
kworker/2:4/2684 is trying to acquire lock:
ffff88814bb1c0a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_rsrc_put_work+0x13d/0x1a0
but task is already holding lock:
ffffc90001c6be70 ((work_completion)(&(&ctx->rsrc_put_work)->work)){+.+.}-{0:0}, at: process_one_work+0x1bc/0x530
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 ((work_completion)(&(&ctx->rsrc_put_work)->work)){+.+.}-{0:0}:
__flush_work+0x31b/0x490
io_rsrc_ref_quiesce.part.0.constprop.0+0x35/0xb0
__do_sys_io_uring_register+0x45b/0x1060
do_syscall_64+0x35/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #0 (&ctx->uring_lock){+.+.}-{3:3}:
__lock_acquire+0x119a/0x1e10
lock_acquire+0xc8/0x2f0
__mutex_lock+0x86/0x740
io_rsrc_put_work+0x13d/0x1a0
process_one_work+0x236/0x530
worker_thread+0x52/0x3b0
kthread+0x135/0x160
ret_from_fork+0x1f/0x30
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock((work_completion)(&(&ctx->rsrc_put_work)->work));
lock(&ctx->uring_lock);
lock((work_completion)(&(&ctx->rsrc_put_work)->work));
lock(&ctx->uring_lock);
*** DEADLOCK ***
2 locks held by kworker/2:4/2684:
#0: ffff88810004d938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x1bc/0x530
#1: ffffc90001c6be70 ((work_completion)(&(&ctx->rsrc_put_work)->work)){+.+.}-{0:0}, at: process_one_work+0x1bc/0x530
stack backtrace:
CPU: 2 PID: 2684 Comm: kworker/2:4 Tainted: G OE 5.14.0-rc3-bluetea-test-00249-gc7d102232649 #5
Hardware name: Acer Aspire ES1-421/OLVIA_BE, BIOS V1.05 07/02/2015
Workqueue: events io_rsrc_put_work
Call Trace:
dump_stack_lvl+0x6a/0x9a
check_noncircular+0xfe/0x110
__lock_acquire+0x119a/0x1e10
lock_acquire+0xc8/0x2f0
? io_rsrc_put_work+0x13d/0x1a0
__mutex_lock+0x86/0x740
? io_rsrc_put_work+0x13d/0x1a0
? io_rsrc_put_work+0x13d/0x1a0
? io_rsrc_put_work+0x13d/0x1a0
? process_one_work+0x1ce/0x530
io_rsrc_put_work+0x13d/0x1a0
process_one_work+0x236/0x530
worker_thread+0x52/0x3b0
? process_one_work+0x530/0x530
kthread+0x135/0x160
? set_kthread_struct+0x40/0x40
ret_from_fork+0x1f/0x30
which is due to holding the ctx->uring_lock when flushing existing
pending work, while the pending work flushing may need to grab the uring
lock if we're using IOPOLL.
Fix this by dropping the uring_lock a bit earlier as part of the flush.
Cc: stable@vger.kernel.org
Link: https://github.com/axboe/liburing/issues/404
Tested-by: Ammar Faizi <ammarfaizi2@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Nadav reports running into the below splat on re-enabling softirqs:
WARNING: CPU: 2 PID: 1777 at kernel/softirq.c:364 __local_bh_enable_ip+0xaa/0xe0
Modules linked in:
CPU: 2 PID: 1777 Comm: umem Not tainted 5.13.1+ #161
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/22/2020
RIP: 0010:__local_bh_enable_ip+0xaa/0xe0
Code: a9 00 ff ff 00 74 38 65 ff 0d a2 21 8c 7a e8 ed 1a 20 00 fb 66 0f 1f 44 00 00 5b 41 5c 5d c3 65 8b 05 e6 2d 8c 7a 85 c0 75 9a <0f> 0b eb 96 e8 2d 1f 20 00 eb a5 4c 89 e7 e8 73 4f 0c 00 eb ae 65
RSP: 0018:ffff88812e58fcc8 EFLAGS: 00010046
RAX: 0000000000000000 RBX: 0000000000000201 RCX: dffffc0000000000
RDX: 0000000000000007 RSI: 0000000000000201 RDI: ffffffff8898c5ac
RBP: ffff88812e58fcd8 R08: ffffffff8575dbbf R09: ffffed1028ef14f9
R10: ffff88814778a7c3 R11: ffffed1028ef14f8 R12: ffffffff85c9e9ae
R13: ffff88814778a000 R14: ffff88814778a7b0 R15: ffff8881086db890
FS: 00007fbcfee17700(0000) GS:ffff8881e0300000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c0402a5008 CR3: 000000011c1ac003 CR4: 00000000003706e0
Call Trace:
_raw_spin_unlock_bh+0x31/0x40
io_rsrc_node_ref_zero+0x13e/0x190
io_dismantle_req+0x215/0x220
io_req_complete_post+0x1b8/0x720
__io_complete_rw.isra.0+0x16b/0x1f0
io_complete_rw+0x10/0x20
where it's clear we end up calling the percpu count release directly
from the completion path, as it's in atomic mode and we drop the last
ref. For file/block IO, this can be from IRQ context already, and the
softirq locking for rsrc isn't enough.
Just make the lock fully IRQ safe, and ensure we correctly safe state
from the release path as we don't know the full context there.
Reported-by: Nadav Amit <nadav.amit@gmail.com>
Tested-by: Nadav Amit <nadav.amit@gmail.com>
Link: https://lore.kernel.org/io-uring/C187C836-E78B-4A31-B24C-D16919ACA093@gmail.com/
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The compiler should be forbidden from any strange optimization for async
writes to user visible data-structures. Without proper protection, the
compiler can cause write-tearing or invent writes that would confuse the
userspace.
However, there are writes to sq_flags which are not protected by
WRITE_ONCE(). Use WRITE_ONCE() for these writes.
This is purely a theoretical issue. Presumably, any compiler is very
unlikely to do such optimizations.
Fixes: 75b28affdd6a ("io_uring: allocate the two rings together")
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Link: https://lore.kernel.org/r/20210808001342.964634-3-namit@vmware.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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When using SQPOLL, the submission queue polling thread calls
task_work_run() to run queued work. However, when work is added with
TWA_SIGNAL - as done by io_uring itself - the TIF_NOTIFY_SIGNAL remains
set afterwards and is never cleared.
Consequently, when the submission queue polling thread checks whether
signal_pending(), it may always find a pending signal, if
task_work_add() was ever called before.
The impact of this bug might be different on different kernel versions.
It appears that on 5.14 it would only cause unnecessary calculation and
prevent the polling thread from sleeping. On 5.13, where the bug was
found, it stops the polling thread from finding newly submitted work.
Instead of task_work_run(), use tracehook_notify_signal() that clears
TIF_NOTIFY_SIGNAL. Test for TIF_NOTIFY_SIGNAL in addition to
current->task_works to avoid a race in which task_works is cleared but
the TIF_NOTIFY_SIGNAL is set.
Fixes: 685fe7feedb96 ("io-wq: eliminate the need for a manager thread")
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Link: https://lore.kernel.org/r/20210808001342.964634-2-namit@vmware.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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For pure poll requests, it doesn't remove the second poll wait entry
when it's done, neither after vfs_poll() or in the poll completion
handler. We should remove the second poll wait entry.
And we use io_poll_remove_double() rather than io_poll_remove_waitqs()
since the latter has some redundant logic.
Fixes: 88e41cf928a6 ("io_uring: add multishot mode for IORING_OP_POLL_ADD")
Cc: stable@vger.kernel.org # 5.13+
Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
Link: https://lore.kernel.org/r/20210728030322.12307-1-haoxu@linux.alibaba.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Some setups, like SCSI, can throw spurious -EAGAIN off the softirq
completion path. Normally we expect this to happen inline as part
of submission, but apparently SCSI has a weird corner case where it
can happen as part of normal completions.
This should be solved by having the -EAGAIN bubble back up the stack
as part of submission, but previous attempts at this failed and we're
not just quite there yet. Instead we currently use REQ_F_REISSUE to
handle this case.
For now, catch it in io_rw_should_reissue() and prevent a reissue
from a bogus path.
Cc: stable@vger.kernel.org
Reported-by: Fabian Ebner <f.ebner@proxmox.com>
Tested-by: Fabian Ebner <f.ebner@proxmox.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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As a safeguard, if we're going to queue async work, do it from task_work
from the original task. This ensures that we can always sanely create
threads, regards of what the reissue context may be.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We use a bit to manage if we need to add the shared task_work, but
a list + lock for the pending work. Before aborting a current run
of the task_work we check if the list is empty, but we do so without
grabbing the lock that protects it. This can lead to races where
we think we have nothing left to run, where in practice we could be
racing with a task adding new work to the list. If we do hit that
race condition, we could be left with work items that need processing,
but the shared task_work is not active.
Ensure that we grab the lock before checking if the list is empty,
so we know if it's safe to exit the run or not.
Link: https://lore.kernel.org/io-uring/c6bd5987-e9ae-cd02-49d0-1b3ac1ef65b1@tnonline.net/
Cc: stable@vger.kernel.org # 5.11+
Reported-by: Forza <forza@tnonline.net>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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