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Date: Tue, 23 Oct 2018 02:42:03 -0700 From: syzbot <syzbot+a50c7541a4a55cd49b02@...kaller.appspotmail.com> To: adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com, tytso@....edu Subject: Re: possible deadlock in flush_workqueue (2) syzbot has found a reproducer for the following crash on: HEAD commit: ca9eb48fe01f Merge tag 'regulator-v5.0' of git://git.kerne.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=11a60939400000 kernel config: https://syzkaller.appspot.com/x/.config?x=963b24abf3f7c2d8 dashboard link: https://syzkaller.appspot.com/bug?extid=a50c7541a4a55cd49b02 compiler: gcc (GCC) 8.0.1 20180413 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12097f03400000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10b55ac5400000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+a50c7541a4a55cd49b02@...kaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected syz-executor460 (5381) used greatest stack depth: 13176 bytes left 4.19.0+ #298 Not tainted ------------------------------------------------------ syz-executor460/5379 is trying to acquire lock: 00000000cba2efd5 ((wq_completion)"dio/%s"sb->s_id){+.+.}, at: flush_workqueue+0x2db/0x1e10 kernel/workqueue.c:2652 but task is already holding lock: 00000000a7636398 (&sb->s_type->i_mutex_key#10){+.+.}, at: inode_trylock include/linux/fs.h:758 [inline] 00000000a7636398 (&sb->s_type->i_mutex_key#10){+.+.}, at: ext4_file_write_iter+0x2a1/0x1420 fs/ext4/file.c:232 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&sb->s_type->i_mutex_key#10){+.+.}: down_write+0x8a/0x130 kernel/locking/rwsem.c:70 inode_lock include/linux/fs.h:738 [inline] __generic_file_fsync+0xb5/0x200 fs/libfs.c:981 ext4_sync_file+0xa4f/0x1510 fs/ext4/fsync.c:120 vfs_fsync_range+0x140/0x220 fs/sync.c:197 generic_write_sync include/linux/fs.h:2732 [inline] dio_complete+0x75c/0x9e0 fs/direct-io.c:329 dio_aio_complete_work+0x20/0x30 fs/direct-io.c:341 process_one_work+0xc90/0x1c40 kernel/workqueue.c:2153 worker_thread+0x17f/0x1390 kernel/workqueue.c:2296 kthread+0x35a/0x420 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413 -> #1 ((work_completion)(&dio->complete_work)){+.+.}: process_one_work+0xc0a/0x1c40 kernel/workqueue.c:2129 worker_thread+0x17f/0x1390 kernel/workqueue.c:2296 kthread+0x35a/0x420 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413 -> #0 ((wq_completion)"dio/%s"sb->s_id){+.+.}: lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3900 flush_workqueue+0x30a/0x1e10 kernel/workqueue.c:2655 drain_workqueue+0x2a9/0x640 kernel/workqueue.c:2820 destroy_workqueue+0xc6/0x9c0 kernel/workqueue.c:4155 sb_init_dio_done_wq+0x74/0x90 fs/direct-io.c:634 do_blockdev_direct_IO+0x12ea/0x9d70 fs/direct-io.c:1283 __blockdev_direct_IO+0x9d/0xc6 fs/direct-io.c:1417 ext4_direct_IO_write fs/ext4/inode.c:3743 [inline] ext4_direct_IO+0xae8/0x2230 fs/ext4/inode.c:3870 generic_file_direct_write+0x275/0x4b0 mm/filemap.c:3042 __generic_file_write_iter+0x2ff/0x630 mm/filemap.c:3221 ext4_file_write_iter+0x390/0x1420 fs/ext4/file.c:266 call_write_iter include/linux/fs.h:1808 [inline] aio_write+0x3b1/0x610 fs/aio.c:1561 io_submit_one+0xaa1/0xf80 fs/aio.c:1835 __do_sys_io_submit fs/aio.c:1916 [inline] __se_sys_io_submit fs/aio.c:1887 [inline] __x64_sys_io_submit+0x1b7/0x580 fs/aio.c:1887 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: (wq_completion)"dio/%s"sb->s_id --> (work_completion)(&dio->complete_work) --> &sb->s_type->i_mutex_key#10 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sb->s_type->i_mutex_key#10); lock((work_completion)(&dio->complete_work)); lock(&sb->s_type->i_mutex_key#10); lock((wq_completion)"dio/%s"sb->s_id); *** DEADLOCK *** 1 lock held by syz-executor460/5379: #0: 00000000a7636398 (&sb->s_type->i_mutex_key#10){+.+.}, at: inode_trylock include/linux/fs.h:758 [inline] #0: 00000000a7636398 (&sb->s_type->i_mutex_key#10){+.+.}, at: ext4_file_write_iter+0x2a1/0x1420 fs/ext4/file.c:232 stack backtrace: CPU: 1 PID: 5379 Comm: syz-executor460 Not tainted 4.19.0+ #298 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1c4/0x2b6 lib/dump_stack.c:113 print_circular_bug.isra.33.cold.54+0x1bd/0x27d kernel/locking/lockdep.c:1221 check_prev_add kernel/locking/lockdep.c:1861 [inline] check_prevs_add kernel/locking/lockdep.c:1974 [inline] validate_chain kernel/locking/lockdep.c:2415 [inline] __lock_acquire+0x33e4/0x4ec0 kernel/locking/lockdep.c:3411 lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3900 flush_workqueue+0x30a/0x1e10 kernel/workqueue.c:2655 drain_workqueue+0x2a9/0x640 kernel/workqueue.c:2820 destroy_workqueue+0xc6/0x9c0 kernel/workqueue.c:4155 sb_init_dio_done_wq+0x74/0x90 fs/direct-io.c:634 do_blockdev_direct_IO+0x12ea/0x9d70 fs/direct-io.c:1283 __blockdev_direct_IO+0x9d/0xc6 fs/direct-io.c:1417 ext4_direct_IO_write fs/ext4/inode.c:3743 [inline] ext4_direct_IO+0xae8/0x2230 fs/ext4/inode.c:3870 generic_file_direct_write+0x275/0x4b0 mm/filemap.c:3042 __generic_file_write_iter+0x2ff/0x630 mm/filemap.c:3221 ext4_file_write_iter+0x390/0x1420 fs/ext4/file.c:266 call_write_iter include/linux/fs.h:1808 [inline] aio_write+0x3b1/0x610 fs/aio.c:1561 io_submit_one+0xaa1/0xf80 fs/aio.c:1835 __do_sys_io_submit fs/aio.c:1916 [inline] __se_sys_io_submit fs/aio.c:1887 [inline] __x64_sys_io_submit+0x1b7/0x580 fs/aio.c:1887 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4469b9 Code: e8 dc e6 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 4b 07 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fbd534a7da8 EFLAGS: 00000246 ORIG_RAX: 00000000000000d1 RAX: ffffffffffffffda RBX: 00000000006dcc48 RCX: 00000000004469b9 RDX: 0000000020000540 RSI: 0000000000000008 RDI: 00007fbd53487000 RBP: 00000000006dcc40 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dcc4c R13: 8000000000044000 R14: 00007fbd534a89c0 R15: 00000000006dcd4c Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O! File: /root/syzkaller.jTMKK3/1/bus PID: 14 Comm: kworker/0:1 Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O! File: /root/syzkaller.jTMKK3/3/bus PID: 14 Comm: kworker/0:1 Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O! File: /root/syzkaller.itrSF4/4/bus PID: 5 Comm: kworker/0:0 Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O! File: /root/syzkaller.itrSF4/5/bus PID: 5 Comm: kworker/0:0 Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O! File: /root/syzkaller.qGPxI4/5/bus PID: 14 Comm: kworker/0:1 Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O! File: /root/syzkaller.qGPxI4/6/bus PID: 5 Comm: kworker/0:0 Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O! File: /root/syzkaller.FhXGz4/9/bus PID: 14 Comm: kworker/0:1 Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O! File: /root/syzkaller.itrSF4/9/bus PID: 5394 Comm: kworker/0:4 Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O! File: /root/syzkaller.FhXGz4/10/bus PID: 5394 Comm: kworker/0:4 Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O! File: /root/syzkaller.qGPxI4/9/bus PID: 5394 Comm: kworker/0:4
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