This is a note to let you know that I've just added the patch titled
io_uring: don't block level reissue off completion path
to the 5.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
io_uring-don-t-block-level-reissue-off-completion-path.patch
and it can be found in the queue-5.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ef04688871f3386b6d40ade8f5c664290420f819 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@xxxxxxxxx>
Date: Tue, 27 Jul 2021 10:50:31 -0600
Subject: io_uring: don't block level reissue off completion path
From: Jens Axboe <axboe@xxxxxxxxx>
commit ef04688871f3386b6d40ade8f5c664290420f819 upstream.
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@xxxxxxxxxxxxxxx
Reported-by: Fabian Ebner <f.ebner@xxxxxxxxxxx>
Tested-by: Fabian Ebner <f.ebner@xxxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/io_uring.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2457,6 +2457,12 @@ static bool io_rw_should_reissue(struct
*/
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
Patches currently in stable-queue which might be from axboe@xxxxxxxxx are
queue-5.13/io_uring-fix-io_prep_async_link-locking.patch
queue-5.13/io_uring-fix-poll-requests-leaking-second-poll-entries.patch
queue-5.13/blk-iocost-fix-operation-ordering-in-iocg_wake_fn.patch
queue-5.13/io_uring-don-t-block-level-reissue-off-completion-path.patch
