Messages in this thread | | | Date | Sat, 20 Oct 2018 09:13:02 -0700 | Subject | Re: possible deadlock in __generic_file_fsync | From | syzbot <> |
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syzbot has found a reproducer for the following crash on:
HEAD commit: 270b77a0f30e Merge tag 'drm-fixes-2018-10-20-1' of git://a.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=146f4ad9400000 kernel config: https://syzkaller.appspot.com/x/.config?x=b3f55cb3dfcc6c33 dashboard link: https://syzkaller.appspot.com/bug?extid=5cd33f0e6abe2bb3e397 compiler: gcc (GCC) 8.0.1 20180413 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1436fc45400000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11058e2d400000
IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+5cd33f0e6abe2bb3e397@syzkaller.appspotmail.com
syz-executor388 (5339) used greatest stack depth: 15944 bytes left syz-executor388 (5337) used greatest stack depth: 15800 bytes left
====================================================== WARNING: possible circular locking dependency detected 4.19.0-rc8+ #293 Not tainted ------------------------------------------------------ kworker/0:1/14 is trying to acquire lock: 000000008e61a3a9 (&sb->s_type->i_mutex_key#10){+.+.}, at: inode_lock include/linux/fs.h:738 [inline] 000000008e61a3a9 (&sb->s_type->i_mutex_key#10){+.+.}, at: __generic_file_fsync+0xb5/0x200 fs/libfs.c:981
but task is already holding lock: 00000000160c39d9 ((work_completion)(&dio->complete_work)){+.+.}, at: process_one_work+0xb9a/0x1b90 kernel/workqueue.c:2128
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 ((work_completion)(&dio->complete_work)){+.+.}: process_one_work+0xc0a/0x1b90 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
-> #1 ((wq_completion)"dio/%s"sb->s_id){+.+.}: 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
-> #0 (&sb->s_type->i_mutex_key#10){+.+.}: lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3900 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+0xc90/0x1b90 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
other info that might help us debug this:
Chain exists of: &sb->s_type->i_mutex_key#10 --> (wq_completion)"dio/%s"sb->s_id --> (work_completion)(&dio->complete_work)
Possible unsafe locking scenario:
CPU0 CPU1 ---- ---- lock((work_completion)(&dio->complete_work)); lock((wq_completion)"dio/%s"sb->s_id); lock((work_completion)(&dio->complete_work)); lock(&sb->s_type->i_mutex_key#10);
*** DEADLOCK ***
2 locks held by kworker/0:1/14: #0: 000000006dbdba7d ((wq_completion)"dio/%s"sb->s_id){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 000000006dbdba7d ((wq_completion)"dio/%s"sb->s_id){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 000000006dbdba7d ((wq_completion)"dio/%s"sb->s_id){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 000000006dbdba7d ((wq_completion)"dio/%s"sb->s_id){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:59 [inline] #0: 000000006dbdba7d ((wq_completion)"dio/%s"sb->s_id){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 000000006dbdba7d ((wq_completion)"dio/%s"sb->s_id){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 000000006dbdba7d ((wq_completion)"dio/%s"sb->s_id){+.+.}, at: process_one_work+0xb43/0x1b90 kernel/workqueue.c:2124 #1: 00000000160c39d9 ((work_completion)(&dio->complete_work)){+.+.}, at: process_one_work+0xb9a/0x1b90 kernel/workqueue.c:2128
stack backtrace: CPU: 0 PID: 14 Comm: kworker/0:1 Not tainted 4.19.0-rc8+ #293 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: dio/sda1 dio_aio_complete_work Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1c4/0x2b4 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 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+0xc90/0x1b90 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 Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O! File: /root/syzkaller.Ay7bpq/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.l9bGzq/7/bus PID: 2682 Comm: kworker/0:2 syz-executor388 (5488) used greatest stack depth: 15128 bytes left syz-executor388 (5560) used greatest stack depth: 14328 bytes left syz-executor388 (5630) used greatest stack depth: 12872 bytes left Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O! File: /root/syzkaller.l9bGzq/18/bus PID: 2682 Comm: kworker/0:2 Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O! File: /root/syzkaller.Ay7bpq/19/bus PID: 2682 Comm: kworker/0:2 Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O! File: /root/syzkaller.Ay7bpq/22/bus PID: 5540 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.ygzABq/30/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.aGaJtq/29/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.qLFhwq/30/bus PID: 5540 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.Ay7bpq/35/bus PID: 5540 Comm: kworker/0:4 syz-executor388 (6261) used greatest stack depth: 12504 bytes left Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O! File: /root/syzkaller.aGaJtq/49/bus PID: 14 Comm: kworker/0:1 syz-executor388 (7306) used greatest stack depth: 12488 bytes left
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