syzbot


possible deadlock in ocfs2_move_extent

Status: upstream: reported on 2025/05/05 22:36
Subsystems: ocfs2
[Documentation on labels]
Reported-by: syzbot+68c788938ba0326046a9@syzkaller.appspotmail.com
First crash: 6d16h, last: 6d16h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [ocfs2?] possible deadlock in ocfs2_move_extent 0 (1) 2025/05/05 22:36

Sample crash report:
loop0: detected capacity change from 0 to 32768
ocfs2: Mounting device (7,0) on (node local, slot 0) with ordered data mode.
======================================================
WARNING: possible circular locking dependency detected
6.15.0-rc4-syzkaller-00052-g4f79eaa2ceac #0 Not tainted
------------------------------------------------------
syz.0.30/6040 is trying to acquire lock:
ffff888076dd5100 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#5){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline]
ffff888076dd5100 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#5){+.+.}-{4:4}, at: ocfs2_move_extent+0x6ea/0x17f0 fs/ocfs2/move_extents.c:640

but task is already holding lock:
ffff88805a106d80 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#6){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline]
ffff88805a106d80 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#6){+.+.}-{4:4}, at: ocfs2_move_extent+0x429/0x17f0 fs/ocfs2/move_extents.c:632

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#6){+.+.}-{4:4}:
       down_write+0x92/0x200 kernel/locking/rwsem.c:1577
       inode_lock include/linux/fs.h:867 [inline]
       __ocfs2_flush_truncate_log+0x31e/0x1160 fs/ocfs2/alloc.c:6054
       ocfs2_flush_truncate_log+0x4a/0x70 fs/ocfs2/alloc.c:6084
       ocfs2_sync_fs+0x1c6/0x3d0 fs/ocfs2/super.c:406
       sync_filesystem+0x1d0/0x290 fs/sync.c:66
       generic_shutdown_super+0x74/0x390 fs/super.c:621
       kill_block_super+0x3b/0x90 fs/super.c:1710
       deactivate_locked_super+0xc1/0x1a0 fs/super.c:473
       deactivate_super fs/super.c:506 [inline]
       deactivate_super+0xde/0x100 fs/super.c:502
       cleanup_mnt+0x225/0x450 fs/namespace.c:1435
       task_work_run+0x150/0x240 kernel/task_work.c:227
       resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
       exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
       exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
       __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
       syscall_exit_to_user_mode+0x27b/0x2a0 kernel/entry/common.c:218
       do_syscall_64+0xda/0x260 arch/x86/entry/syscall_64.c:100
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#5){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3166 [inline]
       check_prevs_add kernel/locking/lockdep.c:3285 [inline]
       validate_chain kernel/locking/lockdep.c:3909 [inline]
       __lock_acquire+0x1173/0x1ba0 kernel/locking/lockdep.c:5235
       lock_acquire kernel/locking/lockdep.c:5866 [inline]
       lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823
       down_write+0x92/0x200 kernel/locking/rwsem.c:1577
       inode_lock include/linux/fs.h:867 [inline]
       ocfs2_move_extent+0x6ea/0x17f0 fs/ocfs2/move_extents.c:640
       __ocfs2_move_extents_range fs/ocfs2/move_extents.c:860 [inline]
       ocfs2_move_extents+0xd69/0x1980 fs/ocfs2/move_extents.c:927
       ocfs2_ioctl_move_extents+0x54d/0xb20 fs/ocfs2/move_extents.c:1053
       ocfs2_ioctl+0x3c6/0x6f0 fs/ocfs2/ioctl.c:946
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl fs/ioctl.c:892 [inline]
       __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#6);
                               lock(&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#5);
                               lock(&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#6);
  lock(&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#5);

 *** DEADLOCK ***

5 locks held by syz.0.30/6040:
 #0: ffff88807ac9a420 (sb_writers#12){.+.+}-{0:0}, at: ocfs2_ioctl_move_extents+0xc4/0xb20 fs/ocfs2/move_extents.c:985
 #1: ffff888076dd5f40 (&sb->s_type->i_mutex_key#20){++++}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline]
 #1: ffff888076dd5f40 (&sb->s_type->i_mutex_key#20){++++}-{4:4}, at: ocfs2_move_extents+0x1c3/0x1980 fs/ocfs2/move_extents.c:905
 #2: ffff888076dd5be0 (&oi->ip_alloc_sem){+.+.}-{4:4}, at: ocfs2_move_extents+0x429/0x1980 fs/ocfs2/move_extents.c:925
 #3: ffff888076dd1800 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#3){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline]
 #3: ffff888076dd1800 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#3){+.+.}-{4:4}, at: ocfs2_reserve_suballoc_bits+0x11c/0x48d0 fs/ocfs2/suballoc.c:786
 #4: ffff88805a106d80 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#6){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline]
 #4: ffff88805a106d80 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#6){+.+.}-{4:4}, at: ocfs2_move_extent+0x429/0x17f0 fs/ocfs2/move_extents.c:632

stack backtrace:
CPU: 1 UID: 0 PID: 6040 Comm: syz.0.30 Not tainted 6.15.0-rc4-syzkaller-00052-g4f79eaa2ceac #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x275/0x350 kernel/locking/lockdep.c:2079
 check_noncircular+0x14c/0x170 kernel/locking/lockdep.c:2211
 check_prev_add kernel/locking/lockdep.c:3166 [inline]
 check_prevs_add kernel/locking/lockdep.c:3285 [inline]
 validate_chain kernel/locking/lockdep.c:3909 [inline]
 __lock_acquire+0x1173/0x1ba0 kernel/locking/lockdep.c:5235
 lock_acquire kernel/locking/lockdep.c:5866 [inline]
 lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823
 down_write+0x92/0x200 kernel/locking/rwsem.c:1577
 inode_lock include/linux/fs.h:867 [inline]
 ocfs2_move_extent+0x6ea/0x17f0 fs/ocfs2/move_extents.c:640
 __ocfs2_move_extents_range fs/ocfs2/move_extents.c:860 [inline]
 ocfs2_move_extents+0xd69/0x1980 fs/ocfs2/move_extents.c:927
 ocfs2_ioctl_move_extents+0x54d/0xb20 fs/ocfs2/move_extents.c:1053
 ocfs2_ioctl+0x3c6/0x6f0 fs/ocfs2/ioctl.c:946
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl fs/ioctl.c:892 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd0fd78e969
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fd0fe5d9038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fd0fd9b5fa0 RCX: 00007fd0fd78e969
RDX: 00002000000000c0 RSI: 0000000040406f06 RDI: 0000000000000004
RBP: 00007fd0fd810ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fd0fd9b5fa0 R15: 00007ffe87be5778
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/05/01 22:35 upstream 4f79eaa2ceac 51b137cd .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root possible deadlock in ocfs2_move_extent
2025/05/01 22:31 upstream 4f79eaa2ceac 51b137cd .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root possible deadlock in ocfs2_move_extent
* Struck through repros no longer work on HEAD.