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io_uring: break out of iowq iopoll on teardown

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io-wq will retry iopoll even when it failed with -EAGAIN. If that
races with task exit, which sets TIF_NOTIFY_SIGNAL for all its workers,
such workers might potentially infinitely spin retrying iopoll again and
again and each time failing on some allocation / waiting / etc. Don't
keep spinning if io-wq is dying.

Fixes: 561fb04a6a ("io_uring: replace workqueue usage with io-wq")
Cc: stable@vger.kernel.org
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2023-09-07 13:50:07 +01:00 committed by Jens Axboe
parent 76d3ccecfa
commit 45500dc4e0
3 changed files with 13 additions and 0 deletions
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10
io_uring/io-wq.c
View File

@ -174,6 +174,16 @@ static void io_worker_ref_put(struct io_wq *wq)
complete(&wq->worker_done);
}
bool io_wq_worker_stopped(void)
{
struct io_worker *worker = current->worker_private;
if (WARN_ON_ONCE(!io_wq_current_is_worker()))
return true;
return test_bit(IO_WQ_BIT_EXIT, &worker->wq->state);
}
static void io_worker_cancel_cb(struct io_worker *worker)
{
struct io_wq_acct *acct = io_wq_get_acct(worker);

1
io_uring/io-wq.h
View File

@ -52,6 +52,7 @@ void io_wq_hash_work(struct io_wq_work *work, void *val);
int io_wq_cpu_affinity(struct io_uring_task *tctx, cpumask_var_t mask);
int io_wq_max_workers(struct io_wq *wq, int *new_count);
bool io_wq_worker_stopped(void);
static inline bool io_wq_is_hashed(struct io_wq_work *work)
{

2
io_uring/io_uring.c
View File

@ -1975,6 +1975,8 @@ fail:
if (!needs_poll) {
if (!(req->ctx->flags & IORING_SETUP_IOPOLL))
break;
if (io_wq_worker_stopped())
break;
cond_resched();
continue;
}