* [PATCH 2/2] io_uring: don't block level reissue off completion path
[not found] <20210727165811.284510-1-axboe@kernel.dk>
@ 2021-07-27 16:58 ` Jens Axboe
2021-07-28 9:26 ` Fabian Ebner
0 siblings, 1 reply; 4+ messages in thread
From: Jens Axboe @ 2021-07-27 16:58 UTC (permalink / raw)
To: io-uring; +Cc: f.ebner, Jens Axboe, stable
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>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
fs/io_uring.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 6ba101cd4661..83f67d33bf67 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2447,6 +2447,12 @@ static bool io_rw_should_reissue(struct io_kiocb *req)
*/
if (percpu_ref_is_dying(&ctx->refs))
return false;
+ /*
+ * Play it safe and assume not safe to re-import and reissue if we're
+ * not in the original thread group (or in task context).
+ */
+ if (!same_thread_group(req->task, current) || !in_task())
+ return false;
return true;
}
#else
--
2.32.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH 2/2] io_uring: don't block level reissue off completion path
2021-07-27 16:58 ` [PATCH 2/2] io_uring: don't block level reissue off completion path Jens Axboe
@ 2021-07-28 9:26 ` Fabian Ebner
2021-07-28 13:23 ` Jens Axboe
0 siblings, 1 reply; 4+ messages in thread
From: Fabian Ebner @ 2021-07-28 9:26 UTC (permalink / raw)
To: Jens Axboe, io-uring; +Cc: stable
Am 27.07.21 um 18:58 schrieb Jens Axboe:
> 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>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> ---
> fs/io_uring.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 6ba101cd4661..83f67d33bf67 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -2447,6 +2447,12 @@ static bool io_rw_should_reissue(struct io_kiocb *req)
> */
> if (percpu_ref_is_dying(&ctx->refs))
> return false;
> + /*
> + * Play it safe and assume not safe to re-import and reissue if we're
> + * not in the original thread group (or in task context).
> + */
> + if (!same_thread_group(req->task, current) || !in_task())
> + return false;
> return true;
> }
> #else
>
Hi,
thank you for the fix! This does indeed prevent the panic (with 5.11.22)
and hang (with 5.13.3) with my problematic workload.
Best Regards,
Fabian
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 2/2] io_uring: don't block level reissue off completion path
2021-07-28 9:26 ` Fabian Ebner
@ 2021-07-28 13:23 ` Jens Axboe
2021-07-29 6:50 ` Fabian Ebner
0 siblings, 1 reply; 4+ messages in thread
From: Jens Axboe @ 2021-07-28 13:23 UTC (permalink / raw)
To: Fabian Ebner, io-uring; +Cc: stable
On 7/28/21 3:26 AM, Fabian Ebner wrote:
> Am 27.07.21 um 18:58 schrieb Jens Axboe:
>> 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>
>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>> ---
>> fs/io_uring.c | 6 ++++++
>> 1 file changed, 6 insertions(+)
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index 6ba101cd4661..83f67d33bf67 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -2447,6 +2447,12 @@ static bool io_rw_should_reissue(struct io_kiocb *req)
>> */
>> if (percpu_ref_is_dying(&ctx->refs))
>> return false;
>> + /*
>> + * Play it safe and assume not safe to re-import and reissue if we're
>> + * not in the original thread group (or in task context).
>> + */
>> + if (!same_thread_group(req->task, current) || !in_task())
>> + return false;
>> return true;
>> }
>> #else
>>
>
> Hi,
>
> thank you for the fix! This does indeed prevent the panic (with 5.11.22)
> and hang (with 5.13.3) with my problematic workload.
Perfect, thanks for re-testing! Can I add your Tested-by to the patch?
--
Jens Axboe
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 2/2] io_uring: don't block level reissue off completion path
2021-07-28 13:23 ` Jens Axboe
@ 2021-07-29 6:50 ` Fabian Ebner
0 siblings, 0 replies; 4+ messages in thread
From: Fabian Ebner @ 2021-07-29 6:50 UTC (permalink / raw)
To: Jens Axboe, io-uring; +Cc: stable
Am 28.07.21 um 15:23 schrieb Jens Axboe:
> On 7/28/21 3:26 AM, Fabian Ebner wrote:
>> Am 27.07.21 um 18:58 schrieb Jens Axboe:
>>> 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>
>>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>>> ---
>>> fs/io_uring.c | 6 ++++++
>>> 1 file changed, 6 insertions(+)
>>>
>>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>>> index 6ba101cd4661..83f67d33bf67 100644
>>> --- a/fs/io_uring.c
>>> +++ b/fs/io_uring.c
>>> @@ -2447,6 +2447,12 @@ static bool io_rw_should_reissue(struct io_kiocb *req)
>>> */
>>> if (percpu_ref_is_dying(&ctx->refs))
>>> return false;
>>> + /*
>>> + * Play it safe and assume not safe to re-import and reissue if we're
>>> + * not in the original thread group (or in task context).
>>> + */
>>> + if (!same_thread_group(req->task, current) || !in_task())
>>> + return false;
>>> return true;
>>> }
>>> #else
>>>
>>
>> Hi,
>>
>> thank you for the fix! This does indeed prevent the panic (with 5.11.22)
>> and hang (with 5.13.3) with my problematic workload.
>
> Perfect, thanks for re-testing! Can I add your Tested-by to the patch?
>
Sure, feel free to do so.
Best Regards,
Fabian
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-07-29 6:50 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
[not found] <20210727165811.284510-1-axboe@kernel.dk>
2021-07-27 16:58 ` [PATCH 2/2] io_uring: don't block level reissue off completion path Jens Axboe
2021-07-28 9:26 ` Fabian Ebner
2021-07-28 13:23 ` Jens Axboe
2021-07-29 6:50 ` Fabian Ebner
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).