| Message ID | 20200805063150.41037-1-colyli@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] block: check queue's limits.discard_granularity in __blkdev_issue_discard() | expand |
On 8/5/20 8:31 AM, Coly Li wrote: > If create a loop device with a backing NVMe SSD, current loop device > driver doesn't correctly set its queue's limits.discard_granularity and > leaves it as 0. If a discard request at LBA 0 on this loop device, in > __blkdev_issue_discard() the calculated req_sects will be 0, and a zero > length discard request will trigger a BUG() panic in generic block layer > code at block/blk-mq.c:563. > > [ 955.565006][ C39] ------------[ cut here ]------------ > [ 955.559660][ C39] invalid opcode: 0000 [#1] SMP NOPTI > [ 955.622171][ C39] CPU: 39 PID: 248 Comm: ksoftirqd/39 Tainted: G E 5.8.0-default+ #40 > [ 955.622171][ C39] Hardware name: Lenovo ThinkSystem SR650 -[7X05CTO1WW]-/-[7X05CTO1WW]-, BIOS -[IVE160M-2.70]- 07/17/2020 > [ 955.622175][ C39] RIP: 0010:blk_mq_end_request+0x107/0x110 > [ 955.622177][ C39] Code: 48 8b 03 e9 59 ff ff ff 48 89 df 5b 5d 41 5c e9 9f ed ff ff 48 8b 35 98 3c f4 00 48 83 c7 10 48 83 c6 19 e8 cb 56 c9 ff eb cb <0f> 0b 0f 1f 80 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 41 56 41 54 > [ 955.622179][ C39] RSP: 0018:ffffb1288701fe28 EFLAGS: 00010202 > [ 955.749277][ C39] RAX: 0000000000000001 RBX: ffff956fffba5080 RCX: 0000000000004003 > [ 955.749278][ C39] RDX: 0000000000000003 RSI: 0000000000000000 RDI: 0000000000000000 > [ 955.749279][ C39] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > [ 955.749279][ C39] R10: ffffb1288701fd28 R11: 0000000000000001 R12: ffffffffa8e05160 > [ 955.749280][ C39] R13: 0000000000000004 R14: 0000000000000004 R15: ffffffffa7ad3a1e > [ 955.749281][ C39] FS: 0000000000000000(0000) GS:ffff95bfbda00000(0000) knlGS:0000000000000000 > [ 955.749282][ C39] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 955.749282][ C39] CR2: 00007f6f0ef766a8 CR3: 0000005a37012002 CR4: 00000000007606e0 > [ 955.749283][ C39] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 955.749284][ C39] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 955.749284][ C39] PKRU: 55555554 > [ 955.749285][ C39] Call Trace: > [ 955.749290][ C39] blk_done_softirq+0x99/0xc0 > [ 957.550669][ C39] __do_softirq+0xd3/0x45f > [ 957.550677][ C39] ? smpboot_thread_fn+0x2f/0x1e0 > [ 957.550679][ C39] ? smpboot_thread_fn+0x74/0x1e0 > [ 957.550680][ C39] ? smpboot_thread_fn+0x14e/0x1e0 > [ 957.550684][ C39] run_ksoftirqd+0x30/0x60 > [ 957.550687][ C39] smpboot_thread_fn+0x149/0x1e0 > [ 957.886225][ C39] ? sort_range+0x20/0x20 > [ 957.886226][ C39] kthread+0x137/0x160 > [ 957.886228][ C39] ? kthread_park+0x90/0x90 > [ 957.886231][ C39] ret_from_fork+0x22/0x30 > [ 959.117120][ C39] ---[ end trace 3dacdac97e2ed164 ]--- > > This is the procedure to reproduce the panic, > # modprobe scsi_debug delay=0 dev_size_mb=2048 max_queue=1 > # losetup -f /dev/nvme0n1 --direct-io=on > # blkdiscard /dev/loop0 -o 0 -l 0x200 > > This patch fixes the issue by checking q->limits.discard_granularity in > __blkdev_issue_discard() before composing the discard bio. If the value > is 0, then prints a warning oops information and returns -EOPNOTSUPP to > the caller to indicate that this buggy device driver doesn't support > discard request. > > Fixes: 9b15d109a6b2 ("block: improve discard bio alignment in __blkdev_issue_discard()") > Fixes: c52abf563049 ("loop: Better discard support for block devices") > Reported-and-suggested-by: Ming Lei <ming.lei@redhat.com> > Signed-off-by: Coly Li <colyli@suse.de> > Reviewed-by: Ming Lei <ming.lei@redhat.com> > Cc: Bart Van Assche <bvanassche@acm.org> > Cc: Christoph Hellwig <hch@lst.de> > Cc: Enzo Matsumiya <ematsumiya@suse.com> > Cc: Evan Green <evgreen@chromium.org> > Cc: Hannes Reinecke <hare@suse.com> > Cc: Jens Axboe <axboe@kernel.dk> > Cc: Martin K. Petersen <martin.petersen@oracle.com> > Cc: Xiao Ni <xni@redhat.com> > --- > Changelog: > v3: print device name assocated with the buggy driver. > v2: fix typo of the wrong return error code. > v1: first version. > > block/blk-lib.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/block/blk-lib.c b/block/blk-lib.c > index 019e09bb9c0e..d3bbb3d9fac3 100644 > --- a/block/blk-lib.c > +++ b/block/blk-lib.c > @@ -47,6 +47,15 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector, > op = REQ_OP_DISCARD; > } > > + /* In case the discard granularity isn't set by buggy device driver */ > + if (WARN_ON_ONCE(!q->limits.discard_granularity)) { > + char dev_name[BDEVNAME_SIZE]; > + > + bdevname(bdev, dev_name); > + pr_err("%s: Error: discard_granularity is 0.\n", dev_name); > + return -EOPNOTSUPP; > + } > + > bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1; > if ((sector | nr_sects) & bs_mask) > return -EINVAL; > Reviewed-by: Hannes Reinecke <hare@suse.de> Cheers, Hannes
Hi Coly, one question below: Coly Li <colyli@suse.de> 于2020年8月5日周三 上午8:36写道： > > If create a loop device with a backing NVMe SSD, current loop device > driver doesn't correctly set its queue's limits.discard_granularity and > leaves it as 0. If a discard request at LBA 0 on this loop device, in > __blkdev_issue_discard() the calculated req_sects will be 0, and a zero > length discard request will trigger a BUG() panic in generic block layer > code at block/blk-mq.c:563. > > [ 955.565006][ C39] ------------[ cut here ]------------ > [ 955.559660][ C39] invalid opcode: 0000 [#1] SMP NOPTI > [ 955.622171][ C39] CPU: 39 PID: 248 Comm: ksoftirqd/39 Tainted: G E 5.8.0-default+ #40 > [ 955.622171][ C39] Hardware name: Lenovo ThinkSystem SR650 -[7X05CTO1WW]-/-[7X05CTO1WW]-, BIOS -[IVE160M-2.70]- 07/17/2020 > [ 955.622175][ C39] RIP: 0010:blk_mq_end_request+0x107/0x110 > [ 955.622177][ C39] Code: 48 8b 03 e9 59 ff ff ff 48 89 df 5b 5d 41 5c e9 9f ed ff ff 48 8b 35 98 3c f4 00 48 83 c7 10 48 83 c6 19 e8 cb 56 c9 ff eb cb <0f> 0b 0f 1f 80 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 41 56 41 54 > [ 955.622179][ C39] RSP: 0018:ffffb1288701fe28 EFLAGS: 00010202 > [ 955.749277][ C39] RAX: 0000000000000001 RBX: ffff956fffba5080 RCX: 0000000000004003 > [ 955.749278][ C39] RDX: 0000000000000003 RSI: 0000000000000000 RDI: 0000000000000000 > [ 955.749279][ C39] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > [ 955.749279][ C39] R10: ffffb1288701fd28 R11: 0000000000000001 R12: ffffffffa8e05160 > [ 955.749280][ C39] R13: 0000000000000004 R14: 0000000000000004 R15: ffffffffa7ad3a1e > [ 955.749281][ C39] FS: 0000000000000000(0000) GS:ffff95bfbda00000(0000) knlGS:0000000000000000 > [ 955.749282][ C39] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 955.749282][ C39] CR2: 00007f6f0ef766a8 CR3: 0000005a37012002 CR4: 00000000007606e0 > [ 955.749283][ C39] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 955.749284][ C39] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 955.749284][ C39] PKRU: 55555554 > [ 955.749285][ C39] Call Trace: > [ 955.749290][ C39] blk_done_softirq+0x99/0xc0 > [ 957.550669][ C39] __do_softirq+0xd3/0x45f > [ 957.550677][ C39] ? smpboot_thread_fn+0x2f/0x1e0 > [ 957.550679][ C39] ? smpboot_thread_fn+0x74/0x1e0 > [ 957.550680][ C39] ? smpboot_thread_fn+0x14e/0x1e0 > [ 957.550684][ C39] run_ksoftirqd+0x30/0x60 > [ 957.550687][ C39] smpboot_thread_fn+0x149/0x1e0 > [ 957.886225][ C39] ? sort_range+0x20/0x20 > [ 957.886226][ C39] kthread+0x137/0x160 > [ 957.886228][ C39] ? kthread_park+0x90/0x90 > [ 957.886231][ C39] ret_from_fork+0x22/0x30 > [ 959.117120][ C39] ---[ end trace 3dacdac97e2ed164 ]--- > > This is the procedure to reproduce the panic, > # modprobe scsi_debug delay=0 dev_size_mb=2048 max_queue=1 Why do you need scsi_debug here, it's not relevant and not used? > # losetup -f /dev/nvme0n1 --direct-io=on > # blkdiscard /dev/loop0 -o 0 -l 0x200 > > This patch fixes the issue by checking q->limits.discard_granularity in > __blkdev_issue_discard() before composing the discard bio. If the value > is 0, then prints a warning oops information and returns -EOPNOTSUPP to > the caller to indicate that this buggy device driver doesn't support > discard request. The patch itself looks correct to me. > > Fixes: 9b15d109a6b2 ("block: improve discard bio alignment in __blkdev_issue_discard()") > Fixes: c52abf563049 ("loop: Better discard support for block devices") > Reported-and-suggested-by: Ming Lei <ming.lei@redhat.com> > Signed-off-by: Coly Li <colyli@suse.de> > Reviewed-by: Ming Lei <ming.lei@redhat.com> > Cc: Bart Van Assche <bvanassche@acm.org> > Cc: Christoph Hellwig <hch@lst.de> > Cc: Enzo Matsumiya <ematsumiya@suse.com> > Cc: Evan Green <evgreen@chromium.org> > Cc: Hannes Reinecke <hare@suse.com> > Cc: Jens Axboe <axboe@kernel.dk> > Cc: Martin K. Petersen <martin.petersen@oracle.com> > Cc: Xiao Ni <xni@redhat.com> Reviewed-by: Jack Wang <jinpu.wang@cloud.ionos.com> Thanks > --- > Changelog: > v3: print device name assocated with the buggy driver. > v2: fix typo of the wrong return error code. > v1: first version. > > block/blk-lib.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/block/blk-lib.c b/block/blk-lib.c > index 019e09bb9c0e..d3bbb3d9fac3 100644 > --- a/block/blk-lib.c > +++ b/block/blk-lib.c > @@ -47,6 +47,15 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector, > op = REQ_OP_DISCARD; > } > > + /* In case the discard granularity isn't set by buggy device driver */ > + if (WARN_ON_ONCE(!q->limits.discard_granularity)) { > + char dev_name[BDEVNAME_SIZE]; > + > + bdevname(bdev, dev_name); > + pr_err("%s: Error: discard_granularity is 0.\n", dev_name); > + return -EOPNOTSUPP; > + } > + > bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1; > if ((sector | nr_sects) & bs_mask) > return -EINVAL; > -- > 2.26.2 >
On 2020/8/5 17:22, Jinpu Wang wrote: > Hi Coly, > > one question below: > Coly Li <colyli@suse.de> 于2020年8月5日周三 上午8:36写道： >> >> If create a loop device with a backing NVMe SSD, current loop device >> driver doesn't correctly set its queue's limits.discard_granularity and >> leaves it as 0. If a discard request at LBA 0 on this loop device, in >> __blkdev_issue_discard() the calculated req_sects will be 0, and a zero >> length discard request will trigger a BUG() panic in generic block layer >> code at block/blk-mq.c:563. >> >> [ 955.565006][ C39] ------------[ cut here ]------------ >> [ 955.559660][ C39] invalid opcode: 0000 [#1] SMP NOPTI >> [ 955.622171][ C39] CPU: 39 PID: 248 Comm: ksoftirqd/39 Tainted: G E 5.8.0-default+ #40 >> [ 955.622171][ C39] Hardware name: Lenovo ThinkSystem SR650 -[7X05CTO1WW]-/-[7X05CTO1WW]-, BIOS -[IVE160M-2.70]- 07/17/2020 >> [ 955.622175][ C39] RIP: 0010:blk_mq_end_request+0x107/0x110 >> [ 955.622177][ C39] Code: 48 8b 03 e9 59 ff ff ff 48 89 df 5b 5d 41 5c e9 9f ed ff ff 48 8b 35 98 3c f4 00 48 83 c7 10 48 83 c6 19 e8 cb 56 c9 ff eb cb <0f> 0b 0f 1f 80 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 41 56 41 54 >> [ 955.622179][ C39] RSP: 0018:ffffb1288701fe28 EFLAGS: 00010202 >> [ 955.749277][ C39] RAX: 0000000000000001 RBX: ffff956fffba5080 RCX: 0000000000004003 >> [ 955.749278][ C39] RDX: 0000000000000003 RSI: 0000000000000000 RDI: 0000000000000000 >> [ 955.749279][ C39] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 >> [ 955.749279][ C39] R10: ffffb1288701fd28 R11: 0000000000000001 R12: ffffffffa8e05160 >> [ 955.749280][ C39] R13: 0000000000000004 R14: 0000000000000004 R15: ffffffffa7ad3a1e >> [ 955.749281][ C39] FS: 0000000000000000(0000) GS:ffff95bfbda00000(0000) knlGS:0000000000000000 >> [ 955.749282][ C39] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> [ 955.749282][ C39] CR2: 00007f6f0ef766a8 CR3: 0000005a37012002 CR4: 00000000007606e0 >> [ 955.749283][ C39] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >> [ 955.749284][ C39] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 >> [ 955.749284][ C39] PKRU: 55555554 >> [ 955.749285][ C39] Call Trace: >> [ 955.749290][ C39] blk_done_softirq+0x99/0xc0 >> [ 957.550669][ C39] __do_softirq+0xd3/0x45f >> [ 957.550677][ C39] ? smpboot_thread_fn+0x2f/0x1e0 >> [ 957.550679][ C39] ? smpboot_thread_fn+0x74/0x1e0 >> [ 957.550680][ C39] ? smpboot_thread_fn+0x14e/0x1e0 >> [ 957.550684][ C39] run_ksoftirqd+0x30/0x60 >> [ 957.550687][ C39] smpboot_thread_fn+0x149/0x1e0 >> [ 957.886225][ C39] ? sort_range+0x20/0x20 >> [ 957.886226][ C39] kthread+0x137/0x160 >> [ 957.886228][ C39] ? kthread_park+0x90/0x90 >> [ 957.886231][ C39] ret_from_fork+0x22/0x30 >> [ 959.117120][ C39] ---[ end trace 3dacdac97e2ed164 ]--- >> >> This is the procedure to reproduce the panic, >> # modprobe scsi_debug delay=0 dev_size_mb=2048 max_queue=1 > Why do you need scsi_debug here, it's not relevant and not used? If I don't config SCSI_DEBUG this panic cannot be triggered in my environment, I don't know why. Maybe it is unnecessary, but in case other people has similar configuration as mine, I add this command line in the commit log. >> # losetup -f /dev/nvme0n1 --direct-io=on >> # blkdiscard /dev/loop0 -o 0 -l 0x200 >> >> This patch fixes the issue by checking q->limits.discard_granularity in >> __blkdev_issue_discard() before composing the discard bio. If the value >> is 0, then prints a warning oops information and returns -EOPNOTSUPP to >> the caller to indicate that this buggy device driver doesn't support >> discard request. > The patch itself looks correct to me. >> >> Fixes: 9b15d109a6b2 ("block: improve discard bio alignment in __blkdev_issue_discard()") >> Fixes: c52abf563049 ("loop: Better discard support for block devices") >> Reported-and-suggested-by: Ming Lei <ming.lei@redhat.com> >> Signed-off-by: Coly Li <colyli@suse.de> >> Reviewed-by: Ming Lei <ming.lei@redhat.com> >> Cc: Bart Van Assche <bvanassche@acm.org> >> Cc: Christoph Hellwig <hch@lst.de> >> Cc: Enzo Matsumiya <ematsumiya@suse.com> >> Cc: Evan Green <evgreen@chromium.org> >> Cc: Hannes Reinecke <hare@suse.com> >> Cc: Jens Axboe <axboe@kernel.dk> >> Cc: Martin K. Petersen <martin.petersen@oracle.com> >> Cc: Xiao Ni <xni@redhat.com> > Reviewed-by: Jack Wang <jinpu.wang@cloud.ionos.com> [snipped] Thanks. Coly Li
On Wed, Aug 05, 2020 at 02:31:50PM +0800, Coly Li wrote: > If create a loop device with a backing NVMe SSD, current loop device > driver doesn't correctly set its queue's limits.discard_granularity and > leaves it as 0. If a discard request at LBA 0 on this loop device, in > __blkdev_issue_discard() the calculated req_sects will be 0, and a zero > length discard request will trigger a BUG() panic in generic block layer > code at block/blk-mq.c:563. > > [ 955.565006][ C39] ------------[ cut here ]------------ > [ 955.559660][ C39] invalid opcode: 0000 [#1] SMP NOPTI > [ 955.622171][ C39] CPU: 39 PID: 248 Comm: ksoftirqd/39 Tainted: G E 5.8.0-default+ #40 > [ 955.622171][ C39] Hardware name: Lenovo ThinkSystem SR650 -[7X05CTO1WW]-/-[7X05CTO1WW]-, BIOS -[IVE160M-2.70]- 07/17/2020 > [ 955.622175][ C39] RIP: 0010:blk_mq_end_request+0x107/0x110 > [ 955.622177][ C39] Code: 48 8b 03 e9 59 ff ff ff 48 89 df 5b 5d 41 5c e9 9f ed ff ff 48 8b 35 98 3c f4 00 48 83 c7 10 48 83 c6 19 e8 cb 56 c9 ff eb cb <0f> 0b 0f 1f 80 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 41 56 41 54 > [ 955.622179][ C39] RSP: 0018:ffffb1288701fe28 EFLAGS: 00010202 > [ 955.749277][ C39] RAX: 0000000000000001 RBX: ffff956fffba5080 RCX: 0000000000004003 > [ 955.749278][ C39] RDX: 0000000000000003 RSI: 0000000000000000 RDI: 0000000000000000 > [ 955.749279][ C39] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > [ 955.749279][ C39] R10: ffffb1288701fd28 R11: 0000000000000001 R12: ffffffffa8e05160 > [ 955.749280][ C39] R13: 0000000000000004 R14: 0000000000000004 R15: ffffffffa7ad3a1e > [ 955.749281][ C39] FS: 0000000000000000(0000) GS:ffff95bfbda00000(0000) knlGS:0000000000000000 > [ 955.749282][ C39] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 955.749282][ C39] CR2: 00007f6f0ef766a8 CR3: 0000005a37012002 CR4: 00000000007606e0 > [ 955.749283][ C39] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 955.749284][ C39] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 955.749284][ C39] PKRU: 55555554 > [ 955.749285][ C39] Call Trace: > [ 955.749290][ C39] blk_done_softirq+0x99/0xc0 > [ 957.550669][ C39] __do_softirq+0xd3/0x45f > [ 957.550677][ C39] ? smpboot_thread_fn+0x2f/0x1e0 > [ 957.550679][ C39] ? smpboot_thread_fn+0x74/0x1e0 > [ 957.550680][ C39] ? smpboot_thread_fn+0x14e/0x1e0 > [ 957.550684][ C39] run_ksoftirqd+0x30/0x60 > [ 957.550687][ C39] smpboot_thread_fn+0x149/0x1e0 > [ 957.886225][ C39] ? sort_range+0x20/0x20 > [ 957.886226][ C39] kthread+0x137/0x160 > [ 957.886228][ C39] ? kthread_park+0x90/0x90 > [ 957.886231][ C39] ret_from_fork+0x22/0x30 > [ 959.117120][ C39] ---[ end trace 3dacdac97e2ed164 ]--- > > This is the procedure to reproduce the panic, > # modprobe scsi_debug delay=0 dev_size_mb=2048 max_queue=1 > # losetup -f /dev/nvme0n1 --direct-io=on > # blkdiscard /dev/loop0 -o 0 -l 0x200 > > This patch fixes the issue by checking q->limits.discard_granularity in > __blkdev_issue_discard() before composing the discard bio. If the value > is 0, then prints a warning oops information and returns -EOPNOTSUPP to > the caller to indicate that this buggy device driver doesn't support > discard request. > > Fixes: 9b15d109a6b2 ("block: improve discard bio alignment in __blkdev_issue_discard()") > Fixes: c52abf563049 ("loop: Better discard support for block devices") > Reported-and-suggested-by: Ming Lei <ming.lei@redhat.com> > Signed-off-by: Coly Li <colyli@suse.de> > Reviewed-by: Ming Lei <ming.lei@redhat.com> > Cc: Bart Van Assche <bvanassche@acm.org> > Cc: Christoph Hellwig <hch@lst.de> > Cc: Enzo Matsumiya <ematsumiya@suse.com> > Cc: Evan Green <evgreen@chromium.org> > Cc: Hannes Reinecke <hare@suse.com> > Cc: Jens Axboe <axboe@kernel.dk> > Cc: Martin K. Petersen <martin.petersen@oracle.com> > Cc: Xiao Ni <xni@redhat.com> > --- > Changelog: > v3: print device name assocated with the buggy driver. > v2: fix typo of the wrong return error code. > v1: first version. > > block/blk-lib.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/block/blk-lib.c b/block/blk-lib.c > index 019e09bb9c0e..d3bbb3d9fac3 100644 > --- a/block/blk-lib.c > +++ b/block/blk-lib.c > @@ -47,6 +47,15 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector, > op = REQ_OP_DISCARD; > } > > + /* In case the discard granularity isn't set by buggy device driver */ > + if (WARN_ON_ONCE(!q->limits.discard_granularity)) { > + char dev_name[BDEVNAME_SIZE]; > + > + bdevname(bdev, dev_name); > + pr_err("%s: Error: discard_granularity is 0.\n", dev_name); Hm, you might want to ratelimit this, before some buggy device + careless program flood dmesg. Also, why is it necessary to WARN_ON_ONCE /and/ pr_err the same condition? --D > + return -EOPNOTSUPP; > + } > + > bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1; > if ((sector | nr_sects) & bs_mask) > return -EINVAL; > -- > 2.26.2 >
On 2020/8/5 23:48, Darrick J. Wong wrote: > On Wed, Aug 05, 2020 at 02:31:50PM +0800, Coly Li wrote: >> If create a loop device with a backing NVMe SSD, current loop device >> driver doesn't correctly set its queue's limits.discard_granularity and >> leaves it as 0. If a discard request at LBA 0 on this loop device, in >> __blkdev_issue_discard() the calculated req_sects will be 0, and a zero >> length discard request will trigger a BUG() panic in generic block layer >> code at block/blk-mq.c:563. >> >> [ 955.565006][ C39] ------------[ cut here ]------------ >> [ 955.559660][ C39] invalid opcode: 0000 [#1] SMP NOPTI >> [ 955.622171][ C39] CPU: 39 PID: 248 Comm: ksoftirqd/39 Tainted: G E 5.8.0-default+ #40 >> [ 955.622171][ C39] Hardware name: Lenovo ThinkSystem SR650 -[7X05CTO1WW]-/-[7X05CTO1WW]-, BIOS -[IVE160M-2.70]- 07/17/2020 >> [ 955.622175][ C39] RIP: 0010:blk_mq_end_request+0x107/0x110 >> [ 955.622177][ C39] Code: 48 8b 03 e9 59 ff ff ff 48 89 df 5b 5d 41 5c e9 9f ed ff ff 48 8b 35 98 3c f4 00 48 83 c7 10 48 83 c6 19 e8 cb 56 c9 ff eb cb <0f> 0b 0f 1f 80 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 41 56 41 54 >> [ 955.622179][ C39] RSP: 0018:ffffb1288701fe28 EFLAGS: 00010202 >> [ 955.749277][ C39] RAX: 0000000000000001 RBX: ffff956fffba5080 RCX: 0000000000004003 >> [ 955.749278][ C39] RDX: 0000000000000003 RSI: 0000000000000000 RDI: 0000000000000000 >> [ 955.749279][ C39] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 >> [ 955.749279][ C39] R10: ffffb1288701fd28 R11: 0000000000000001 R12: ffffffffa8e05160 >> [ 955.749280][ C39] R13: 0000000000000004 R14: 0000000000000004 R15: ffffffffa7ad3a1e >> [ 955.749281][ C39] FS: 0000000000000000(0000) GS:ffff95bfbda00000(0000) knlGS:0000000000000000 >> [ 955.749282][ C39] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> [ 955.749282][ C39] CR2: 00007f6f0ef766a8 CR3: 0000005a37012002 CR4: 00000000007606e0 >> [ 955.749283][ C39] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >> [ 955.749284][ C39] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 >> [ 955.749284][ C39] PKRU: 55555554 >> [ 955.749285][ C39] Call Trace: >> [ 955.749290][ C39] blk_done_softirq+0x99/0xc0 >> [ 957.550669][ C39] __do_softirq+0xd3/0x45f >> [ 957.550677][ C39] ? smpboot_thread_fn+0x2f/0x1e0 >> [ 957.550679][ C39] ? smpboot_thread_fn+0x74/0x1e0 >> [ 957.550680][ C39] ? smpboot_thread_fn+0x14e/0x1e0 >> [ 957.550684][ C39] run_ksoftirqd+0x30/0x60 >> [ 957.550687][ C39] smpboot_thread_fn+0x149/0x1e0 >> [ 957.886225][ C39] ? sort_range+0x20/0x20 >> [ 957.886226][ C39] kthread+0x137/0x160 >> [ 957.886228][ C39] ? kthread_park+0x90/0x90 >> [ 957.886231][ C39] ret_from_fork+0x22/0x30 >> [ 959.117120][ C39] ---[ end trace 3dacdac97e2ed164 ]--- >> >> This is the procedure to reproduce the panic, >> # modprobe scsi_debug delay=0 dev_size_mb=2048 max_queue=1 >> # losetup -f /dev/nvme0n1 --direct-io=on >> # blkdiscard /dev/loop0 -o 0 -l 0x200 >> >> This patch fixes the issue by checking q->limits.discard_granularity in >> __blkdev_issue_discard() before composing the discard bio. If the value >> is 0, then prints a warning oops information and returns -EOPNOTSUPP to >> the caller to indicate that this buggy device driver doesn't support >> discard request. >> >> Fixes: 9b15d109a6b2 ("block: improve discard bio alignment in __blkdev_issue_discard()") >> Fixes: c52abf563049 ("loop: Better discard support for block devices") >> Reported-and-suggested-by: Ming Lei <ming.lei@redhat.com> >> Signed-off-by: Coly Li <colyli@suse.de> >> Reviewed-by: Ming Lei <ming.lei@redhat.com> >> Cc: Bart Van Assche <bvanassche@acm.org> >> Cc: Christoph Hellwig <hch@lst.de> >> Cc: Enzo Matsumiya <ematsumiya@suse.com> >> Cc: Evan Green <evgreen@chromium.org> >> Cc: Hannes Reinecke <hare@suse.com> >> Cc: Jens Axboe <axboe@kernel.dk> >> Cc: Martin K. Petersen <martin.petersen@oracle.com> >> Cc: Xiao Ni <xni@redhat.com> >> --- >> Changelog: >> v3: print device name assocated with the buggy driver. >> v2: fix typo of the wrong return error code. >> v1: first version. >> >> block/blk-lib.c | 9 +++++++++ >> 1 file changed, 9 insertions(+) >> >> diff --git a/block/blk-lib.c b/block/blk-lib.c >> index 019e09bb9c0e..d3bbb3d9fac3 100644 >> --- a/block/blk-lib.c >> +++ b/block/blk-lib.c >> @@ -47,6 +47,15 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector, >> op = REQ_OP_DISCARD; >> } >> >> + /* In case the discard granularity isn't set by buggy device driver */ >> + if (WARN_ON_ONCE(!q->limits.discard_granularity)) { >> + char dev_name[BDEVNAME_SIZE]; >> + >> + bdevname(bdev, dev_name); >> + pr_err("%s: Error: discard_granularity is 0.\n", dev_name); > > Hm, you might want to ratelimit this, before some buggy device + > careless program flood dmesg. > Sure, I will use pr_err_ratelimit() in next version. > Also, why is it necessary to WARN_ON_ONCE /and/ pr_err the same > condition? > The WARN_ON_ONCE() just though the warning message, but does not point out which device is buggy. Indeed this is a serious problem, so current kernel message is a warning oops info and followed by "loop: Error: discard_granularity is 0." Thanks. Coly Li
diff --git a/block/blk-lib.c b/block/blk-lib.c index 019e09bb9c0e..d3bbb3d9fac3 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -47,6 +47,15 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector, op = REQ_OP_DISCARD; } + /* In case the discard granularity isn't set by buggy device driver */ + if (WARN_ON_ONCE(!q->limits.discard_granularity)) { + char dev_name[BDEVNAME_SIZE]; + + bdevname(bdev, dev_name); + pr_err("%s: Error: discard_granularity is 0.\n", dev_name); + return -EOPNOTSUPP; + } + bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1; if ((sector | nr_sects) & bs_mask) return -EINVAL;
If create a loop device with a backing NVMe SSD, current loop device driver doesn't correctly set its queue's limits.discard_granularity and leaves it as 0. If a discard request at LBA 0 on this loop device, in __blkdev_issue_discard() the calculated req_sects will be 0, and a zero length discard request will trigger a BUG() panic in generic block layer code at block/blk-mq.c:563. [ 955.565006][ C39] ------------[ cut here ]------------ [ 955.559660][ C39] invalid opcode: 0000 [#1] SMP NOPTI [ 955.622171][ C39] CPU: 39 PID: 248 Comm: ksoftirqd/39 Tainted: G E 5.8.0-default+ #40 [ 955.622171][ C39] Hardware name: Lenovo ThinkSystem SR650 -[7X05CTO1WW]-/-[7X05CTO1WW]-, BIOS -[IVE160M-2.70]- 07/17/2020 [ 955.622175][ C39] RIP: 0010:blk_mq_end_request+0x107/0x110 [ 955.622177][ C39] Code: 48 8b 03 e9 59 ff ff ff 48 89 df 5b 5d 41 5c e9 9f ed ff ff 48 8b 35 98 3c f4 00 48 83 c7 10 48 83 c6 19 e8 cb 56 c9 ff eb cb <0f> 0b 0f 1f 80 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 41 56 41 54 [ 955.622179][ C39] RSP: 0018:ffffb1288701fe28 EFLAGS: 00010202 [ 955.749277][ C39] RAX: 0000000000000001 RBX: ffff956fffba5080 RCX: 0000000000004003 [ 955.749278][ C39] RDX: 0000000000000003 RSI: 0000000000000000 RDI: 0000000000000000 [ 955.749279][ C39] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 [ 955.749279][ C39] R10: ffffb1288701fd28 R11: 0000000000000001 R12: ffffffffa8e05160 [ 955.749280][ C39] R13: 0000000000000004 R14: 0000000000000004 R15: ffffffffa7ad3a1e [ 955.749281][ C39] FS: 0000000000000000(0000) GS:ffff95bfbda00000(0000) knlGS:0000000000000000 [ 955.749282][ C39] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 955.749282][ C39] CR2: 00007f6f0ef766a8 CR3: 0000005a37012002 CR4: 00000000007606e0 [ 955.749283][ C39] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 955.749284][ C39] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 955.749284][ C39] PKRU: 55555554 [ 955.749285][ C39] Call Trace: [ 955.749290][ C39] blk_done_softirq+0x99/0xc0 [ 957.550669][ C39] __do_softirq+0xd3/0x45f [ 957.550677][ C39] ? smpboot_thread_fn+0x2f/0x1e0 [ 957.550679][ C39] ? smpboot_thread_fn+0x74/0x1e0 [ 957.550680][ C39] ? smpboot_thread_fn+0x14e/0x1e0 [ 957.550684][ C39] run_ksoftirqd+0x30/0x60 [ 957.550687][ C39] smpboot_thread_fn+0x149/0x1e0 [ 957.886225][ C39] ? sort_range+0x20/0x20 [ 957.886226][ C39] kthread+0x137/0x160 [ 957.886228][ C39] ? kthread_park+0x90/0x90 [ 957.886231][ C39] ret_from_fork+0x22/0x30 [ 959.117120][ C39] ---[ end trace 3dacdac97e2ed164 ]--- This is the procedure to reproduce the panic, # modprobe scsi_debug delay=0 dev_size_mb=2048 max_queue=1 # losetup -f /dev/nvme0n1 --direct-io=on # blkdiscard /dev/loop0 -o 0 -l 0x200 This patch fixes the issue by checking q->limits.discard_granularity in __blkdev_issue_discard() before composing the discard bio. If the value is 0, then prints a warning oops information and returns -EOPNOTSUPP to the caller to indicate that this buggy device driver doesn't support discard request. Fixes: 9b15d109a6b2 ("block: improve discard bio alignment in __blkdev_issue_discard()") Fixes: c52abf563049 ("loop: Better discard support for block devices") Reported-and-suggested-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Coly Li <colyli@suse.de> Reviewed-by: Ming Lei <ming.lei@redhat.com> Cc: Bart Van Assche <bvanassche@acm.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Enzo Matsumiya <ematsumiya@suse.com> Cc: Evan Green <evgreen@chromium.org> Cc: Hannes Reinecke <hare@suse.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Martin K. Petersen <martin.petersen@oracle.com> Cc: Xiao Ni <xni@redhat.com> --- Changelog: v3: print device name assocated with the buggy driver. v2: fix typo of the wrong return error code. v1: first version. block/blk-lib.c | 9 +++++++++ 1 file changed, 9 insertions(+)