possible deadlock in jbd2_log_wait_commit

Status: auto-obsoleted due to no activity on 2026/07/12 02:17
Reported-by: syzbot+7c666b6a43467d68098e@syzkaller.appspotmail.com
First crash: 130d, last: 114d
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 possible deadlock in jbd2_log_wait_commit 4 29 397d 594d 0/3 auto-obsoleted due to no activity on 2025/09/29 15:37
linux-5.15 possible deadlock in jbd2_log_wait_commit (2) origin:lts-only 4 C error 502 6h59m 217d 0/3 upstream: reported C repro on 2025/12/20 23:03
upstream possible deadlock in jbd2_log_wait_commit ext4 4 C done 429 1219d 1243d 22/29 fixed on 2023/06/08 14:41

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.2.1392/10056 is trying to acquire lock:
ffff88805277e990 (jbd2_handle){++++}-{0:0}, at: jbd2_log_wait_commit+0x153/0x4c0 fs/jbd2/journal.c:694

but task is already holding lock:
ffff888048c93f60 (&ocfs2_quota_ip_alloc_sem_key){++++}-{3:3}, at: ocfs2_write_begin+0x19f/0x320 fs/ocfs2/aops.c:1902

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&ocfs2_quota_ip_alloc_sem_key){++++}-{3:3}:
       down_write+0x36/0x60 kernel/locking/rwsem.c:1573
       ocfs2_create_local_dquot+0x1a5/0x18e0 fs/ocfs2/quota_local.c:1224
       ocfs2_acquire_dquot+0x7c6/0xb20 fs/ocfs2/quota_global.c:871
       dqget+0x778/0xeb0 fs/quota/dquot.c:988
       __dquot_initialize+0x3c3/0xcd0 fs/quota/dquot.c:1517
       ocfs2_get_init_inode+0x144/0x1b0 fs/ocfs2/namei.c:202
       ocfs2_mknod+0x8c8/0x25b0 fs/ocfs2/namei.c:310
       ocfs2_mkdir+0x1b6/0x4b0 fs/ocfs2/namei.c:657
       vfs_mkdir+0x387/0x570 fs/namei.c:4114
       do_mkdirat+0x1d8/0x440 fs/namei.c:4139
       __do_sys_mkdirat fs/namei.c:4154 [inline]
       __se_sys_mkdirat fs/namei.c:4152 [inline]
       __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4152
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #2 (&dquot->dq_lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x12d/0xaf0 kernel/locking/mutex.c:747
       dquot_commit+0x5a/0x410 fs/quota/dquot.c:507
       ext4_write_dquot+0x1f0/0x360 fs/ext4/super.c:6811
       mark_dquot_dirty fs/quota/dquot.c:372 [inline]
       mark_all_dquot_dirty+0xf9/0x400 fs/quota/dquot.c:412
       __dquot_alloc_space+0x5fc/0xe60 fs/quota/dquot.c:1752
       dquot_alloc_space_nodirty include/linux/quotaops.h:300 [inline]
       dquot_alloc_space include/linux/quotaops.h:313 [inline]
       dquot_alloc_block include/linux/quotaops.h:337 [inline]
       ext4_mb_new_blocks+0xf8d/0x4760 fs/ext4/mballoc.c:5736
       ext4_ext_map_blocks+0x195b/0x6810 fs/ext4/extents.c:4346
       ext4_map_blocks+0x9de/0x1b70 fs/ext4/inode.c:679
       ext4_iomap_alloc fs/ext4/inode.c:3438 [inline]
       ext4_iomap_begin+0x7fa/0xb10 fs/ext4/inode.c:3488
       iomap_iter+0x6c6/0x1040 fs/iomap/iter.c:91
       __iomap_dio_rw+0x138f/0x1e30 fs/iomap/direct-io.c:597
       iomap_dio_rw+0x41/0xa0 fs/iomap/direct-io.c:686
       ext4_dio_write_iter fs/ext4/file.c:554 [inline]
       ext4_file_write_iter+0x12b7/0x1710 fs/ext4/file.c:674
       do_iter_readv_writev fs/read_write.c:-1 [inline]
       do_iter_write+0x642/0xb10 fs/read_write.c:861
       iter_file_splice_write+0x699/0xcc0 fs/splice.c:685
       do_splice_from fs/splice.c:763 [inline]
       direct_splice_actor+0xe1/0x130 fs/splice.c:950
       splice_direct_to_actor+0x48b/0xb90 fs/splice.c:896
       do_splice_direct+0x1ce/0x2f0 fs/splice.c:1002
       do_sendfile+0x5f3/0xea0 fs/read_write.c:1255
       __do_sys_sendfile64 fs/read_write.c:1323 [inline]
       __se_sys_sendfile64+0x141/0x1a0 fs/read_write.c:1309
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #1 (&ei->i_data_sem){++++}-{3:3}:
       down_write+0x36/0x60 kernel/locking/rwsem.c:1573
       ext4_truncate+0x999/0x1240 fs/ext4/inode.c:4290
       ext4_setattr+0x10cb/0x19f0 fs/ext4/inode.c:5649
       notify_change+0xc74/0xf40 fs/attr.c:499
       do_truncate+0x1ac/0x240 fs/open.c:65
       do_sys_ftruncate+0x312/0x3c0 fs/open.c:193
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (jbd2_handle){++++}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain kernel/locking/lockdep.c:3825 [inline]
       __lock_acquire+0x2d07/0x7d10 kernel/locking/lockdep.c:5049
       lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
       jbd2_log_wait_commit+0x16c/0x4c0 fs/jbd2/journal.c:694
       ocfs2_try_to_free_truncate_log+0x316/0x350 fs/ocfs2/alloc.c:6142
       ocfs2_write_begin_nolock+0x3437/0x44f0 fs/ocfs2/aops.c:1870
       ocfs2_write_begin+0x1c2/0x320 fs/ocfs2/aops.c:1904
       generic_perform_write+0x2fa/0x5c0 mm/filemap.c:3862
       __generic_file_write_iter+0x148/0x2a0 mm/filemap.c:3960
       ocfs2_file_write_iter+0x1660/0x1f00 fs/ocfs2/file.c:2469
       call_write_iter include/linux/fs.h:2265 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x4b1/0xa30 fs/read_write.c:584
       ksys_pwrite64 fs/read_write.c:699 [inline]
       __do_sys_pwrite64 fs/read_write.c:709 [inline]
       __se_sys_pwrite64 fs/read_write.c:706 [inline]
       __x64_sys_pwrite64+0x197/0x220 fs/read_write.c:706
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

Chain exists of:
  jbd2_handle --> &dquot->dq_lock --> &ocfs2_quota_ip_alloc_sem_key

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ocfs2_quota_ip_alloc_sem_key);
                               lock(&dquot->dq_lock);
                               lock(&ocfs2_quota_ip_alloc_sem_key);
  lock(jbd2_handle);

 *** DEADLOCK ***

3 locks held by syz.2.1392/10056:
 #0: ffff888052fae460 (sb_writers#28){.+.+}-{0:0}, at: vfs_write+0x26b/0xa30 fs/read_write.c:580
 #1: ffff888048c942c8 (&sb->s_type->i_mutex_key#37){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff888048c942c8 (&sb->s_type->i_mutex_key#37){+.+.}-{3:3}, at: ocfs2_file_write_iter+0x448/0x1f00 fs/ocfs2/file.c:2399
 #2: ffff888048c93f60 (&ocfs2_quota_ip_alloc_sem_key){++++}-{3:3}, at: ocfs2_write_begin+0x19f/0x320 fs/ocfs2/aops.c:1902

stack backtrace:
CPU: 1 PID: 10056 Comm: syz.2.1392 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain kernel/locking/lockdep.c:3825 [inline]
 __lock_acquire+0x2d07/0x7d10 kernel/locking/lockdep.c:5049
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
 jbd2_log_wait_commit+0x16c/0x4c0 fs/jbd2/journal.c:694
 ocfs2_try_to_free_truncate_log+0x316/0x350 fs/ocfs2/alloc.c:6142
 ocfs2_write_begin_nolock+0x3437/0x44f0 fs/ocfs2/aops.c:1870
 ocfs2_write_begin+0x1c2/0x320 fs/ocfs2/aops.c:1904
 generic_perform_write+0x2fa/0x5c0 mm/filemap.c:3862
 __generic_file_write_iter+0x148/0x2a0 mm/filemap.c:3960
 ocfs2_file_write_iter+0x1660/0x1f00 fs/ocfs2/file.c:2469
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x4b1/0xa30 fs/read_write.c:584
 ksys_pwrite64 fs/read_write.c:699 [inline]
 __do_sys_pwrite64 fs/read_write.c:709 [inline]
 __se_sys_pwrite64 fs/read_write.c:706 [inline]
 __x64_sys_pwrite64+0x197/0x220 fs/read_write.c:706
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f8067d9c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f8068c91028 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007f8068015fa0 RCX: 00007f8067d9c799
RDX: 0000000000000001 RSI: 0000200000000140 RDI: 0000000000000005
RBP: 00007f8067e32c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000008000c61 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8068016038 R14: 00007f8068015fa0 R15: 00007ffcacf185d8
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/17 07:13 linux-6.1.y f2ddafa93a25 0737c18f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in jbd2_log_wait_commit
2026/04/03 02:16 linux-6.1.y 1989cd3d56e2 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in jbd2_log_wait_commit
* Struck through repros no longer work on HEAD.