[syzbot] [ocfs2?] possible deadlock in __ocfs2_move_extents_range

From: syzbot
Date: Thu Mar 13 2025 - 20:08:44 EST

Next message: Chen Wang: "Re: [PATCH v3 0/2] (no cover subject)"
Previous message: Kees Cook: "Re: [PATCH 1/2] lib/vsprintf: Add support for generic FourCCs by extending %p4cc"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Hello,

syzbot found the following issue on:

HEAD commit: 0fed89a961ea Merge tag 'hyperv-fixes-signed-20250311' of g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1390f7a8580000
kernel config: https://syzkaller.appspot.com/x/.config?x=efbd4e7089941bb6
dashboard link: https://syzkaller.appspot.com/bug?extid=783d8c425076dd97018d
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/34fe3a1cd06b/disk-0fed89a9.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7b9d33db76c1/vmlinux-0fed89a9.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3f513f3da6de/bzImage-0fed89a9.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+783d8c425076dd97018d@xxxxxxxxxxxxxxxxxxxxxxxxx

ocfs2: Mounting device (7,5) on (node local, slot 0) with ordered data mode.
======================================================
WARNING: possible circular locking dependency detected
6.14.0-rc6-syzkaller-00016-g0fed89a961ea #0 Not tainted
------------------------------------------------------
syz.5.525/7461 is trying to acquire lock:
ffff88806d75b480 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#6){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:877 [inline]
ffff88806d75b480 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#6){+.+.}-{4:4}, at: ocfs2_move_extent fs/ocfs2/move_extents.c:640 [inline]
ffff88806d75b480 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#6){+.+.}-{4:4}, at: __ocfs2_move_extents_range+0x1f0b/0x4440 fs/ocfs2/move_extents.c:860

but task is already holding lock:
ffff888057c05f40 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#5){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:877 [inline]
ffff888057c05f40 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#5){+.+.}-{4:4}, at: ocfs2_move_extent fs/ocfs2/move_extents.c:632 [inline]
ffff888057c05f40 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#5){+.+.}-{4:4}, at: __ocfs2_move_extents_range+0x168f/0x4440 fs/ocfs2/move_extents.c:860

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]#5){+.+.}-{4:4}:
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
down_write+0x99/0x220 kernel/locking/rwsem.c:1577
inode_lock include/linux/fs.h:877 [inline]
__ocfs2_flush_truncate_log+0x388/0x1240 fs/ocfs2/alloc.c:6046
ocfs2_flush_truncate_log+0x4f/0x70 fs/ocfs2/alloc.c:6076
ocfs2_sync_fs+0x125/0x390 fs/ocfs2/super.c:406
sync_filesystem+0x1ca/0x230 fs/sync.c:66
generic_shutdown_super+0x72/0x2d0 fs/super.c:621
kill_block_super+0x44/0x90 fs/super.c:1710
deactivate_locked_super+0xc6/0x130 fs/super.c:473
cleanup_mnt+0x41f/0x4b0 fs/namespace.c:1413
task_work_run+0x251/0x310 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+0x13f/0x340 kernel/entry/common.c:218
do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#6){+.+.}-{4:4}:
check_prev_add kernel/locking/lockdep.c:3163 [inline]
check_prevs_add kernel/locking/lockdep.c:3282 [inline]
validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906
__lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
down_write+0x99/0x220 kernel/locking/rwsem.c:1577
inode_lock include/linux/fs.h:877 [inline]
ocfs2_move_extent fs/ocfs2/move_extents.c:640 [inline]
__ocfs2_move_extents_range+0x1f0b/0x4440 fs/ocfs2/move_extents.c:860
ocfs2_move_extents+0x3ee/0xac0 fs/ocfs2/move_extents.c:927
ocfs2_ioctl_move_extents+0x61a/0x830 fs/ocfs2/move_extents.c:1053
ocfs2_ioctl+0x196/0x7d0 fs/ocfs2/ioctl.c:946
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl+0xf7/0x170 fs/ioctl.c:892
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
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]#5);
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);

*** DEADLOCK ***

5 locks held by syz.5.525/7461:
#0: ffff888029ea2420 (sb_writers#14){.+.+}-{0:0}, at: mnt_want_write_file+0x5e/0x200 fs/namespace.c:591
#1: ffff88806d75c2c0 (&sb->s_type->i_mutex_key#22){++++}-{4:4}, at: inode_lock include/linux/fs.h:877 [inline]
#1: ffff88806d75c2c0 (&sb->s_type->i_mutex_key#22){++++}-{4:4}, at: ocfs2_move_extents+0x1c5/0xac0 fs/ocfs2/move_extents.c:905
#2: ffff88806d75bf60 (&ocfs2_file_ip_alloc_sem_key){++++}-{4:4}, at: ocfs2_move_extents+0x3cb/0xac0 fs/ocfs2/move_extents.c:925
#3: ffff888057c01800 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#3){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:877 [inline]
#3: ffff888057c01800 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#3){+.+.}-{4:4}, at: ocfs2_reserve_suballoc_bits+0x192/0x4e70 fs/ocfs2/suballoc.c:786
#4: ffff888057c05f40 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#5){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:877 [inline]
#4: ffff888057c05f40 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#5){+.+.}-{4:4}, at: ocfs2_move_extent fs/ocfs2/move_extents.c:632 [inline]
#4: ffff888057c05f40 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#5){+.+.}-{4:4}, at: __ocfs2_move_extents_range+0x168f/0x4440 fs/ocfs2/move_extents.c:860

stack backtrace:
CPU: 1 UID: 0 PID: 7461 Comm: syz.5.525 Not tainted 6.14.0-rc6-syzkaller-00016-g0fed89a961ea #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2076
check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2208
check_prev_add kernel/locking/lockdep.c:3163 [inline]
check_prevs_add kernel/locking/lockdep.c:3282 [inline]
validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906
__lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
down_write+0x99/0x220 kernel/locking/rwsem.c:1577
inode_lock include/linux/fs.h:877 [inline]
ocfs2_move_extent fs/ocfs2/move_extents.c:640 [inline]
__ocfs2_move_extents_range+0x1f0b/0x4440 fs/ocfs2/move_extents.c:860
ocfs2_move_extents+0x3ee/0xac0 fs/ocfs2/move_extents.c:927
ocfs2_ioctl_move_extents+0x61a/0x830 fs/ocfs2/move_extents.c:1053
ocfs2_ioctl+0x196/0x7d0 fs/ocfs2/ioctl.c:946
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl+0xf7/0x170 fs/ioctl.c:892
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f34aa38d169
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:00007f34ab23c038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f34aa5a5fa0 RCX: 00007f34aa38d169
RDX: 00004000000000c0 RSI: 0000000040406f06 RDI: 0000000000000004
RBP: 00007f34aa40e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f34aa5a5fa0 R15: 00007fff34a1f218
</TASK>

---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

Next message: Chen Wang: "Re: [PATCH v3 0/2] (no cover subject)"
Previous message: Kees Cook: "Re: [PATCH 1/2] lib/vsprintf: Add support for generic FourCCs by extending %p4cc"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]