Hi Suwan, Thanks for the fast reply! On Tue, Aug 2, 2022 at 1:55 AM Kim Suwan <suwan.kim027@xxxxxxxxx> wrote: > > Hi Alexandre, > > Thanks for reporting the issue. > > I think a possible scenario is that request fails at > virtio_queue_rqs() and it is passed to normal path (virtio_queue_rq). > > In this procedure, It is possible that blk_mq_start_request() > was called twice changing request state from MQ_RQ_IN_FLIGHT to > MQ_RQ_IN_FLIGHT. I have checked whether virtblk_prep_rq_batch() within virtio_queue_rqs() ever returns 0, and it looks like it never happens. So as far as I can tell all virtio_queue_rqs() are processed successfully - but maybe the request can also fail further down the line? Is there some extra instrumentation I can do to check that? > > Could I know if the issue occurs every booting time? This is consistently happening at every boot, yes. However as I started adding printks here and there to try and figure out what was happening I have a harder time hitting that warning, suggesting a race condition somewhere... FWIW I have checked the status of the request that triggered the warning and as expected it is IN_FLIGHT. Cheers, Alex. > > Regards, > Suwan Kim > > > On Mon, Aug 1, 2022 at 3:11 PM Alexandre Courbot <acourbot@xxxxxxxxxxxx> wrote: > > > > Hi, > > > > I am getting this warning when booting a 5.19 Linux guest on crosvm > > (5.18 did not have this issue): > > > > [ 1.890468] ------------[ cut here ]------------ > > [ 1.890776] WARNING: CPU: 2 PID: 122 at block/blk-mq.c:1143 > > blk_mq_start_request+0x8a/0xe0 > > [ 1.891045] Modules linked in: > > [ 1.891250] CPU: 2 PID: 122 Comm: journal-offline Not tainted 5.19.0+ #44 > > [ 1.891504] Hardware name: ChromiumOS crosvm, BIOS 0 > > [ 1.891739] RIP: 0010:blk_mq_start_request+0x8a/0xe0 > > [ 1.891961] Code: 12 80 74 22 48 8b 4b 10 8b 89 64 01 00 00 8b 53 > > 20 83 fa ff 75 08 ba 00 00 00 80 0b 53 24 c1 e1 10 09 d1 89 48 34 5b > > 41 5e c3 <0f> 0b eb b8 65 8b 05 2b 39 b6 7e 89 c0 48 0f a3 05 39 77 5b > > 01 0f > > [ 1.892443] RSP: 0018:ffffc900002777b0 EFLAGS: 00010202 > > [ 1.892673] RAX: 0000000000000000 RBX: ffff888004bc0000 RCX: 0000000000000000 > > [ 1.892952] RDX: 0000000000000000 RSI: ffff888003d7c200 RDI: ffff888004bc0000 > > [ 1.893228] RBP: 0000000000000000 R08: 0000000000000001 R09: ffff888004bc0100 > > [ 1.893506] R10: ffffffffffffffff R11: ffffffff8185ca10 R12: ffff888004bc0000 > > [ 1.893797] R13: ffffc90000277900 R14: ffff888004ab2340 R15: ffff888003d86e00 > > [ 1.894060] FS: 00007ffa143a4640(0000) GS:ffff88807dd00000(0000) > > knlGS:0000000000000000 > > [ 1.894412] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 1.894682] CR2: 00005648577d9088 CR3: 00000000053da004 CR4: 0000000000170ee0 > > [ 1.894953] Call Trace: > > [ 1.895139] <TASK> > > [ 1.895303] virtblk_prep_rq+0x1e5/0x280 > > [ 1.895509] virtio_queue_rq+0x5c/0x310 > > [ 1.895710] ? virtqueue_add_sgs+0x95/0xb0 > > [ 1.895905] ? _raw_spin_unlock_irqrestore+0x16/0x30 > > [ 1.896133] ? virtio_queue_rqs+0x340/0x390 > > [ 1.896453] ? sbitmap_get+0xfa/0x220 > > [ 1.896678] __blk_mq_issue_directly+0x41/0x180 > > [ 1.896906] blk_mq_plug_issue_direct+0xd8/0x2c0 > > [ 1.897115] blk_mq_flush_plug_list+0x115/0x180 > > [ 1.897342] blk_add_rq_to_plug+0x51/0x130 > > [ 1.897543] blk_mq_submit_bio+0x3a1/0x570 > > [ 1.897750] submit_bio_noacct_nocheck+0x418/0x520 > > [ 1.897985] ? submit_bio_noacct+0x1e/0x260 > > [ 1.897989] ext4_bio_write_page+0x222/0x420 > > [ 1.898000] mpage_process_page_bufs+0x178/0x1c0 > > [ 1.899451] mpage_prepare_extent_to_map+0x2d2/0x440 > > [ 1.899603] ext4_writepages+0x495/0x1020 > > [ 1.899733] do_writepages+0xcb/0x220 > > [ 1.899871] ? __seccomp_filter+0x171/0x7e0 > > [ 1.900006] file_write_and_wait_range+0xcd/0xf0 > > [ 1.900167] ext4_sync_file+0x72/0x320 > > [ 1.900308] __x64_sys_fsync+0x66/0xa0 > > [ 1.900449] do_syscall_64+0x31/0x50 > > [ 1.900595] entry_SYSCALL_64_after_hwframe+0x63/0xcd > > [ 1.900747] RIP: 0033:0x7ffa16ec96ea > > [ 1.900883] Code: b8 4a 00 00 00 0f 05 48 3d 00 f0 ff ff 77 41 c3 > > 48 83 ec 18 89 7c 24 0c e8 e3 02 f8 ff 8b 7c 24 0c 89 c2 b8 4a 00 00 > > 00 0f 05 <48> 3d 00 f0 ff ff 77 36 89 d7 89 44 24 0c e8 43 03 f8 ff 8b > > 44 24 > > [ 1.901302] RSP: 002b:00007ffa143a3ac0 EFLAGS: 00000293 ORIG_RAX: > > 000000000000004a > > [ 1.901499] RAX: ffffffffffffffda RBX: 0000560277ec6fe0 RCX: 00007ffa16ec96ea > > [ 1.901696] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000016 > > [ 1.901884] RBP: 0000560277ec5910 R08: 0000000000000000 R09: 00007ffa143a4640 > > [ 1.902082] R10: 00007ffa16e4d39e R11: 0000000000000293 R12: 00005602773f59e0 > > [ 1.902459] R13: 0000000000000000 R14: 00007fffbfc007ff R15: 00007ffa13ba4000 > > [ 1.902763] </TASK> > > [ 1.902877] ---[ end trace 0000000000000000 ]--- > > > > Apparently the state of the queue is not as expected, for some reason: > > > > WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IDLE); > > > > Reverting 0e9911fa768f removes the warning, as does commenting out the > > queue_rqs op of the virtio-blk device. > > > > I am not particularly versed in the block device layer so thought I > > would report this first. Please let me know if I can provide more > > information. > > > > Cheers, > > Alex.
