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@xxxxxxxxxxxxxxx
Reported-by: Fabian Ebner <f.ebner@xxxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
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
