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io_uring: fix work_exit sqpoll cancellations

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After closing an SQPOLL ring, io_ring_exit_work() kicks in and starts
doing cancellations via io_uring_try_cancel_requests(). It will go
through io_uring_try_cancel_iowq(), which uses ctx->tctx_list, but as
SQPOLL task don't have a ctx note, its io-wq won't be reachable and so
is left not cancelled.

It will eventually cancelled when one of the tasks dies, but if a thread
group survives for long and changes rings, it will spawn lots of
unreclaimed resources and live locked works.

Cancel SQPOLL task's io-wq separately in io_ring_exit_work().

Cc: stable@vger.kernel.org
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/a71a7fe345135d684025bb529d5cb1d8d6b46e10.1619389911.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2021-04-25 23:34:45 +01:00 committed by Jens Axboe
parent 615cee49b3
commit 28090c1338
1 changed files with 18 additions and 7 deletions
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25
fs/io_uring.c
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@ -8679,6 +8679,13 @@ static void io_tctx_exit_cb(struct callback_head *cb)
complete(&work->completion);
}
static bool io_cancel_ctx_cb(struct io_wq_work *work, void *data)
{
struct io_kiocb *req = container_of(work, struct io_kiocb, work);
return req->ctx == data;
}
static void io_ring_exit_work(struct work_struct *work)
{
struct io_ring_ctx *ctx = container_of(work, struct io_ring_ctx, exit_work);
@ -8695,6 +8702,17 @@ static void io_ring_exit_work(struct work_struct *work)
*/
do {
io_uring_try_cancel_requests(ctx, NULL, NULL);
if (ctx->sq_data) {
struct io_sq_data *sqd = ctx->sq_data;
struct task_struct *tsk;
io_sq_thread_park(sqd);
tsk = sqd->thread;
if (tsk && tsk->io_uring && tsk->io_uring->io_wq)
io_wq_cancel_cb(tsk->io_uring->io_wq,
io_cancel_ctx_cb, ctx, true);
io_sq_thread_unpark(sqd);
}
WARN_ON_ONCE(time_after(jiffies, timeout));
} while (!wait_for_completion_timeout(&ctx->ref_comp, HZ/20));
@ -8844,13 +8862,6 @@ static bool io_cancel_defer_files(struct io_ring_ctx *ctx,
return true;
}
static bool io_cancel_ctx_cb(struct io_wq_work *work, void *data)
{
struct io_kiocb *req = container_of(work, struct io_kiocb, work);
return req->ctx == data;
}
static bool io_uring_try_cancel_iowq(struct io_ring_ctx *ctx)
{
struct io_tctx_node *node;