On Tue, Dec 18, 2018 at 07:45:51PM -0500, Sasha Levin wrote: > This is a note to let you know that I've just added the patch titled > > block/loop: fix deadlock after loop_set_status > > to the 3.18-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: > block-loop-fix-deadlock-after-loop_set_status.patch > and it can be found in the queue-3.18 subdirectory. > > If you, or anyone else, feels it should not be added to the stable tree, > please let <[email protected]> know about it. > > > > commit 352efb22c71d30d72d60f364cb8ea8a16408b985 > Author: Tetsuo Handa <[email protected]> > Date: Fri Apr 6 10:03:17 2018 +0900 > > block/loop: fix deadlock after loop_set_status > > [ Upstream commit 1e047eaab3bb5564f25b41e9cd3a053009f4e789 ] > > syzbot is reporting deadlocks at __blkdev_get() [1]. > > ---------------------------------------- > [ 92.493919] systemd-udevd D12696 525 1 0x00000000 > [ 92.495891] Call Trace: > [ 92.501560] schedule+0x23/0x80 > [ 92.502923] schedule_preempt_disabled+0x5/0x10 > [ 92.504645] __mutex_lock+0x416/0x9e0 > [ 92.510760] __blkdev_get+0x73/0x4f0 > [ 92.512220] blkdev_get+0x12e/0x390 > [ 92.518151] do_dentry_open+0x1c3/0x2f0 > [ 92.519815] path_openat+0x5d9/0xdc0 > [ 92.521437] do_filp_open+0x7d/0xf0 > [ 92.527365] do_sys_open+0x1b8/0x250 > [ 92.528831] do_syscall_64+0x6e/0x270 > [ 92.530341] entry_SYSCALL_64_after_hwframe+0x42/0xb7 > > [ 92.931922] 1 lock held by systemd-udevd/525: > [ 92.933642] #0: 00000000a2849e25 (&bdev->bd_mutex){+.+.}, at: > __blkdev_get+0x73/0x4f0 > ---------------------------------------- > > The reason of deadlock turned out that wait_event_interruptible() in > blk_queue_enter() got stuck with bdev->bd_mutex held at __blkdev_put() > due to q->mq_freeze_depth == 1. > > ---------------------------------------- > [ 92.787172] a.out S12584 634 633 0x80000002 > [ 92.789120] Call Trace: > [ 92.796693] schedule+0x23/0x80 > [ 92.797994] blk_queue_enter+0x3cb/0x540 > [ 92.803272] generic_make_request+0xf0/0x3d0 > [ 92.807970] submit_bio+0x67/0x130 > [ 92.810928] submit_bh_wbc+0x15e/0x190 > [ 92.812461] __block_write_full_page+0x218/0x460 > [ 92.815792] __writepage+0x11/0x50 > [ 92.817209] write_cache_pages+0x1ae/0x3d0 > [ 92.825585] generic_writepages+0x5a/0x90 > [ 92.831865] do_writepages+0x43/0xd0 > [ 92.836972] __filemap_fdatawrite_range+0xc1/0x100 > [ 92.838788] filemap_write_and_wait+0x24/0x70 > [ 92.840491] __blkdev_put+0x69/0x1e0 > [ 92.841949] blkdev_close+0x16/0x20 > [ 92.843418] __fput+0xda/0x1f0 > [ 92.844740] task_work_run+0x87/0xb0 > [ 92.846215] do_exit+0x2f5/0xba0 > [ 92.850528] do_group_exit+0x34/0xb0 > [ 92.852018] SyS_exit_group+0xb/0x10 > [ 92.853449] do_syscall_64+0x6e/0x270 > [ 92.854944] entry_SYSCALL_64_after_hwframe+0x42/0xb7 > > [ 92.943530] 1 lock held by a.out/634: > [ 92.945105] #0: 00000000a2849e25 (&bdev->bd_mutex){+.+.}, at: > __blkdev_put+0x3c/0x1e0 > ---------------------------------------- > > The reason of q->mq_freeze_depth == 1 turned out that loop_set_status() > forgot to call blk_mq_unfreeze_queue() at error paths for > info->lo_encrypt_type != NULL case. > > ---------------------------------------- > [ 37.509497] CPU: 2 PID: 634 Comm: a.out Tainted: G W > 4.16.0+ #457 > [ 37.513608] Hardware name: VMware, Inc. VMware Virtual Platform/440BX > Desktop Reference Platform, BIOS 6.00 05/19/2017 > [ 37.518832] RIP: 0010:blk_freeze_queue_start+0x17/0x40 > [ 37.521778] RSP: 0018:ffffb0c2013e7c60 EFLAGS: 00010246 > [ 37.524078] RAX: 0000000000000000 RBX: ffff8b07b1519798 RCX: > 0000000000000000 > [ 37.527015] RDX: 0000000000000002 RSI: ffffb0c2013e7cc0 RDI: > ffff8b07b1519798 > [ 37.529934] RBP: ffffb0c2013e7cc0 R08: 0000000000000008 R09: > 47a189966239b898 > [ 37.532684] R10: dad78b99b278552f R11: 9332dca72259d5ef R12: > ffff8b07acd73678 > [ 37.535452] R13: 0000000000004c04 R14: 0000000000000000 R15: > ffff8b07b841e940 > [ 37.538186] FS: 00007fede33b9740(0000) GS:ffff8b07b8e80000(0000) > knlGS:0000000000000000 > [ 37.541168] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 37.543590] CR2: 00000000206fdf18 CR3: 0000000130b30006 CR4: > 00000000000606e0 > [ 37.546410] Call Trace: > [ 37.547902] blk_freeze_queue+0x9/0x30 > [ 37.549968] loop_set_status+0x67/0x3c0 [loop] > [ 37.549975] loop_set_status64+0x3b/0x70 [loop] > [ 37.549986] lo_ioctl+0x223/0x810 [loop] > [ 37.549995] blkdev_ioctl+0x572/0x980 > [ 37.550003] block_ioctl+0x34/0x40 > [ 37.550006] do_vfs_ioctl+0xa7/0x6d0 > [ 37.550017] ksys_ioctl+0x6b/0x80 > [ 37.573076] SyS_ioctl+0x5/0x10 > [ 37.574831] do_syscall_64+0x6e/0x270 > [ 37.576769] entry_SYSCALL_64_after_hwframe+0x42/0xb7 > ---------------------------------------- > > [1] > https://syzkaller.appspot.com/bug?id=cd662bc3f6022c0979d01a262c318fab2ee9b56f > > Signed-off-by: Tetsuo Handa <[email protected]> > Reported-by: syzbot > <bot+48594378e9851eab70bcd6f99327c7db58c5a...@syzkaller.appspotmail.com> > Fixes: ecdd09597a572513 ("block/loop: fix race between I/O and > set_status") > Cc: Ming Lei <[email protected]> > Cc: Dmitry Vyukov <[email protected]> > Cc: stable <[email protected]> > Cc: Jens Axboe <[email protected]> > Signed-off-by: Jens Axboe <[email protected]> > > Signed-off-by: Sasha Levin <[email protected]> > > diff --git a/drivers/block/loop.c b/drivers/block/loop.c > index 15157a3eabb4..5ad99bc5ac84 100644 > --- a/drivers/block/loop.c > +++ b/drivers/block/loop.c > @@ -1095,11 +1095,15 @@ loop_set_status(struct loop_device *lo, const struct > loop_info64 *info) > if (info->lo_encrypt_type) { > unsigned int type = info->lo_encrypt_type; > > - if (type >= MAX_LO_CRYPT) > - return -EINVAL; > + if (type >= MAX_LO_CRYPT) { > + err = -EINVAL; > + goto exit; > + } > xfer = xfer_funcs[type]; > - if (xfer == NULL) > - return -EINVAL; > + if (xfer == NULL) { > + err = -EINVAL; > + goto exit; > + } > } else > xfer = NULL; >
This breaks the build on the 3.18.y kernel, so I have dropped it from the tree. greg k-h
