* [PATCH 1/3] io_uring: always progress task_work on task cancel
2020-12-20 13:21 [PATCH 0/3] task/files cancellation fixes Pavel Begunkov
@ 2020-12-20 13:21 ` Pavel Begunkov
2020-12-20 13:21 ` [PATCH 2/3] io_uring: end waiting before task cancel attempts Pavel Begunkov
` (2 subsequent siblings)
3 siblings, 0 replies; 6+ messages in thread
From: Pavel Begunkov @ 2020-12-20 13:21 UTC (permalink / raw)
To: Jens Axboe, io-uring
Might happen that __io_uring_cancel_task_requests() cancels nothing but
there are task_works pending. We need to always run them.
Signed-off-by: Pavel Begunkov <[email protected]>
---
fs/io_uring.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index f3690dfdd564..051461b5bf52 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8794,9 +8794,9 @@ static void __io_uring_cancel_task_requests(struct io_ring_ctx *ctx,
ret |= io_poll_remove_all(ctx, task, NULL);
ret |= io_kill_timeouts(ctx, task, NULL);
+ ret |= io_run_task_work();
if (!ret)
break;
- io_run_task_work();
cond_resched();
}
}
--
2.24.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH 2/3] io_uring: end waiting before task cancel attempts
2020-12-20 13:21 [PATCH 0/3] task/files cancellation fixes Pavel Begunkov
2020-12-20 13:21 ` [PATCH 1/3] io_uring: always progress task_work on task cancel Pavel Begunkov
@ 2020-12-20 13:21 ` Pavel Begunkov
2020-12-20 13:21 ` [PATCH 3/3] io_uring: fix cancellation hangs Pavel Begunkov
2020-12-20 18:01 ` [PATCH 0/3] task/files cancellation fixes Pavel Begunkov
3 siblings, 0 replies; 6+ messages in thread
From: Pavel Begunkov @ 2020-12-20 13:21 UTC (permalink / raw)
To: Jens Axboe, io-uring
Get rid of TASK_UNINTERRUPTIBLE and waiting with finish_wait before
going for next iteration in __io_uring_task_cancel(), because
__io_uring_files_cancel() doesn't expect that sheduling is disallowed.
Signed-off-by: Pavel Begunkov <[email protected]>
---
fs/io_uring.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 051461b5bf52..30edf47a8f1a 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8982,9 +8982,9 @@ void __io_uring_task_cancel(void)
if (inflight != tctx_inflight(tctx))
continue;
schedule();
+ finish_wait(&tctx->wait, &wait);
} while (1);
- finish_wait(&tctx->wait, &wait);
atomic_dec(&tctx->in_idle);
}
--
2.24.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 3/3] io_uring: fix cancellation hangs
2020-12-20 13:21 [PATCH 0/3] task/files cancellation fixes Pavel Begunkov
2020-12-20 13:21 ` [PATCH 1/3] io_uring: always progress task_work on task cancel Pavel Begunkov
2020-12-20 13:21 ` [PATCH 2/3] io_uring: end waiting before task cancel attempts Pavel Begunkov
@ 2020-12-20 13:21 ` Pavel Begunkov
2020-12-20 18:01 ` [PATCH 0/3] task/files cancellation fixes Pavel Begunkov
3 siblings, 0 replies; 6+ messages in thread
From: Pavel Begunkov @ 2020-12-20 13:21 UTC (permalink / raw)
To: Jens Axboe, io-uring
We may enter files cancellation with requests that we want to cancel and
that are currently enqueued as task_work. However, before that happens
do_exit() sets PF_EXITING, disabling io_run_task_work() and so locking
up cancellation.
Also, if run between setting PF_EXITING and exit_task_work(), as the
case exit_files() and so io_uring cancellation, task_work_add() might
actually enqueue more task works.
Signed-off-by: Pavel Begunkov <[email protected]>
---
fs/io_uring.c | 6 ------
1 file changed, 6 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 30edf47a8f1a..941fe9b64fd9 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2357,12 +2357,6 @@ static inline unsigned int io_put_rw_kbuf(struct io_kiocb *req)
static inline bool io_run_task_work(void)
{
- /*
- * Not safe to run on exiting task, and the task_work handling will
- * not add work to such a task.
- */
- if (unlikely(current->flags & PF_EXITING))
- return false;
if (current->task_works) {
__set_current_state(TASK_RUNNING);
task_work_run();
--
2.24.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH 0/3] task/files cancellation fixes
2020-12-20 13:21 [PATCH 0/3] task/files cancellation fixes Pavel Begunkov
` (2 preceding siblings ...)
2020-12-20 13:21 ` [PATCH 3/3] io_uring: fix cancellation hangs Pavel Begunkov
@ 2020-12-20 18:01 ` Pavel Begunkov
2020-12-20 18:05 ` Jens Axboe
3 siblings, 1 reply; 6+ messages in thread
From: Pavel Begunkov @ 2020-12-20 18:01 UTC (permalink / raw)
To: Jens Axboe, io-uring
On 20/12/2020 13:21, Pavel Begunkov wrote:
> First two are only for task cancellation, the last one for both.
>
> Jens, do you remember the exact reason why you added the check
> removed in [3/3]? I have a clue, but that stuff doesn't look
> right regardless. See "exit: do exit_task_work() before shooting
> off mm" thread.
The question is answered, the bug is still here, but that's too
early for 3/3. Please consider first 2 patches.
>
> Pavel Begunkov (3):
> io_uring: always progress task_work on task cancel
> io_uring: end waiting before task cancel attempts
> io_uring: fix cancellation hangs
>
> fs/io_uring.c | 10 ++--------
> 1 file changed, 2 insertions(+), 8 deletions(-)
>
--
Pavel Begunkov
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH 0/3] task/files cancellation fixes
2020-12-20 18:01 ` [PATCH 0/3] task/files cancellation fixes Pavel Begunkov
@ 2020-12-20 18:05 ` Jens Axboe
0 siblings, 0 replies; 6+ messages in thread
From: Jens Axboe @ 2020-12-20 18:05 UTC (permalink / raw)
To: Pavel Begunkov, io-uring
On 12/20/20 11:01 AM, Pavel Begunkov wrote:
> On 20/12/2020 13:21, Pavel Begunkov wrote:
>> First two are only for task cancellation, the last one for both.
>>
>> Jens, do you remember the exact reason why you added the check
>> removed in [3/3]? I have a clue, but that stuff doesn't look
>> right regardless. See "exit: do exit_task_work() before shooting
>> off mm" thread.
>
> The question is answered, the bug is still here, but that's too
> early for 3/3. Please consider first 2 patches.
Yep, first two look good to me, thanks!
--
Jens Axboe
^ permalink raw reply [flat|nested] 6+ messages in thread