On Wed, Jul 28, 2021 at 02:09:40PM +0200, Philippe Mathieu-Daudé wrote:
Cc'ing the maintainers for you. See
https://wiki.qemu.org/Contribute/SubmitAPatch#CC_the_relevant_maintainer
$ ./scripts/get_maintainer.pl -f block/io_uring.c
Aarushi Mehta <mehta.aar...@gmail.com> (maintainer:Linux io_uring)
Julia Suvorova <jus...@redhat.com> (maintainer:Linux io_uring)
Stefan Hajnoczi <stefa...@redhat.com> (maintainer:Linux io_uring)
Kevin Wolf <kw...@redhat.com> (supporter:Block layer core)
Max Reitz <mre...@redhat.com> (supporter:Block layer core)
qemu-bl...@nongnu.org (open list:Linux io_uring)
qemu-devel@nongnu.org (open list:All patches CC here)
Also Cc'ing Stefano for commit b4e44c9944e ("io_uring: retry
io_uring_submit() if it fails with errno=EINTR").
Thanks Phil!
(Stefano, you might want to add yourself a R: tag in MAINTAINERS).
Yep, I'll send a patch for that.
On 7/28/21 12:35 PM, Fabian Ebner wrote:
Quoting from [0]:
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.
Host kernels without patch [0] can panic when this happens [1], and
resubmitting makes the panic more likely. On the other hand, for
kernels with patch [0], resubmitting ensures that a block job is not
aborted just because of such spurious errors.
[0]:
https://lore.kernel.org/io-uring/20210727165811.284510-3-ax...@kernel.dk/T/#u
[1]:
#9 [ffffb732000c8b70] asm_exc_page_fault at ffffffffa4800ade
#10 [ffffb732000c8bf8] io_prep_async_work at ffffffffa3d89c16
#11 [ffffb732000c8c50] io_rw_reissue at ffffffffa3d8b2e1
#12 [ffffb732000c8c78] io_complete_rw at ffffffffa3d8baa8
#13 [ffffb732000c8c98] blkdev_bio_end_io at ffffffffa3d62a80
#14 [ffffb732000c8cc8] bio_endio at ffffffffa3f4e800
#15 [ffffb732000c8ce8] dec_pending at ffffffffa432f854
#16 [ffffb732000c8d30] clone_endio at ffffffffa433170c
#17 [ffffb732000c8d70] bio_endio at ffffffffa3f4e800
#18 [ffffb732000c8d90] blk_update_request at ffffffffa3f53a37
#19 [ffffb732000c8dd0] scsi_end_request at ffffffffa4233a5c
#20 [ffffb732000c8e08] scsi_io_completion at ffffffffa423432c
#21 [ffffb732000c8e58] scsi_finish_command at ffffffffa422c527
#22 [ffffb732000c8e88] scsi_softirq_done at ffffffffa42341e4
Signed-off-by: Fabian Ebner <f.eb...@proxmox.com>
---
I'm new to this code and io_uring, so I don't know what all the
implications are, but retrying upon EAGAIN does not sound like
a bad thing to my inexperienced ears.
Yeah, that doesn't sound bad.
For kernels that don't have the patch applied, I don't think there's
much we can do about it, so this change seems okay to me:
Reviewed-by: Stefano Garzarella <sgarz...@redhat.com>
