* [PATCH 5.15] io_uring: fix ltimeout unprep
@ 2021-10-20 1:26 Pavel Begunkov
2021-10-20 1:48 ` Jens Axboe
0 siblings, 1 reply; 4+ messages in thread
From: Pavel Begunkov @ 2021-10-20 1:26 UTC (permalink / raw)
To: io-uring; +Cc: Jens Axboe, Pavel Begunkov, Beld Zhang
io_unprep_linked_timeout() is broken, first it needs to return back
REQ_F_ARM_LTIMEOUT, so the linked timeout is enqueued and disarmed. But
now we refcounted it, and linked timeouts may get not executed at all,
leaking a request.
Just kill the unprep optimisation.
Fixes: 906c6caaf5861 ("io_uring: optimise io_prep_linked_timeout()")
Reported-by: Beld Zhang <[email protected]>
Signed-off-by: Pavel Begunkov <[email protected]>
---
fs/io_uring.c | 9 ---------
1 file changed, 9 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index c87931d8b503..18de14a9e7a4 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1406,11 +1406,6 @@ static inline void io_req_track_inflight(struct io_kiocb *req)
}
}
-static inline void io_unprep_linked_timeout(struct io_kiocb *req)
-{
- req->flags &= ~REQ_F_LINK_TIMEOUT;
-}
-
static struct io_kiocb *__io_prep_linked_timeout(struct io_kiocb *req)
{
if (WARN_ON_ONCE(!req->link))
@@ -6892,10 +6887,6 @@ static void io_queue_sqe_arm_apoll(struct io_kiocb *req)
switch (io_arm_poll_handler(req)) {
case IO_APOLL_READY:
- if (linked_timeout) {
- io_unprep_linked_timeout(req);
- linked_timeout = NULL;
- }
io_req_task_queue(req);
break;
case IO_APOLL_ABORTED:
--
2.33.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH 5.15] io_uring: fix ltimeout unprep
2021-10-20 1:26 [PATCH 5.15] io_uring: fix ltimeout unprep Pavel Begunkov
@ 2021-10-20 1:48 ` Jens Axboe
2021-10-20 8:33 ` Pavel Begunkov
0 siblings, 1 reply; 4+ messages in thread
From: Jens Axboe @ 2021-10-20 1:48 UTC (permalink / raw)
To: Pavel Begunkov, io-uring; +Cc: Beld Zhang
On 10/19/21 7:26 PM, Pavel Begunkov wrote:
> io_unprep_linked_timeout() is broken, first it needs to return back
> REQ_F_ARM_LTIMEOUT, so the linked timeout is enqueued and disarmed. But
> now we refcounted it, and linked timeouts may get not executed at all,
> leaking a request.
>
> Just kill the unprep optimisation.
This appears to be against something that is not 5.15, can you please
check the end result:
https://git.kernel.dk/cgit/linux-block/commit/?h=io_uring-5.15&id=46cb76b2f5ff39bf019bf7a072524fc7fe6deb01
--
Jens Axboe
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 5.15] io_uring: fix ltimeout unprep
2021-10-20 1:48 ` Jens Axboe
@ 2021-10-20 8:33 ` Pavel Begunkov
2021-10-20 8:45 ` Pavel Begunkov
0 siblings, 1 reply; 4+ messages in thread
From: Pavel Begunkov @ 2021-10-20 8:33 UTC (permalink / raw)
To: Jens Axboe, io-uring; +Cc: Beld Zhang
On 10/20/21 02:48, Jens Axboe wrote:
> On 10/19/21 7:26 PM, Pavel Begunkov wrote:
>> io_unprep_linked_timeout() is broken, first it needs to return back
>> REQ_F_ARM_LTIMEOUT, so the linked timeout is enqueued and disarmed. But
>> now we refcounted it, and linked timeouts may get not executed at all,
>> leaking a request.
>>
>> Just kill the unprep optimisation.
>
> This appears to be against something that is not 5.15, can you please
> check the end result:
Yeah, it was 5.16 for some reason. Looks good, thanks!
> https://git.kernel.dk/cgit/linux-block/commit/?h=io_uring-5.15&id=46cb76b2f5ff39bf019bf7a072524fc7fe6deb01
--
Pavel Begunkov
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 5.15] io_uring: fix ltimeout unprep
2021-10-20 8:33 ` Pavel Begunkov
@ 2021-10-20 8:45 ` Pavel Begunkov
0 siblings, 0 replies; 4+ messages in thread
From: Pavel Begunkov @ 2021-10-20 8:45 UTC (permalink / raw)
To: Jens Axboe, io-uring; +Cc: Beld Zhang
On 10/20/21 09:33, Pavel Begunkov wrote:
> On 10/20/21 02:48, Jens Axboe wrote:
>> On 10/19/21 7:26 PM, Pavel Begunkov wrote:
>>> io_unprep_linked_timeout() is broken, first it needs to return back
>>> REQ_F_ARM_LTIMEOUT, so the linked timeout is enqueued and disarmed. But
>>> now we refcounted it, and linked timeouts may get not executed at all,
>>> leaking a request.
>>>
>>> Just kill the unprep optimisation.
>>
>> This appears to be against something that is not 5.15, can you please
>> check the end result:
>
> Yeah, it was 5.16 for some reason. Looks good, thanks!
Actually, it's not. We need either unprep but "smarter" or queue the
timeout. I'll send a v2 for convenience, but a fold in is below.
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 36db7b76cf8d..d5cc103224f1 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6979,6 +6979,8 @@ static void __io_queue_sqe(struct io_kiocb *req)
switch (io_arm_poll_handler(req)) {
case IO_APOLL_READY:
+ if (linked_timeout)
+ io_queue_linked_timeout(linked_timeout);
goto issue_sqe;
case IO_APOLL_ABORTED:
/*
--
Pavel Begunkov
^ permalink raw reply related [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-10-20 8:45 UTC | newest]
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2021-10-20 1:26 [PATCH 5.15] io_uring: fix ltimeout unprep Pavel Begunkov
2021-10-20 1:48 ` Jens Axboe
2021-10-20 8:33 ` Pavel Begunkov
2021-10-20 8:45 ` Pavel Begunkov
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