WARNING in ext4_journal_check_start

Status: upstream: reported C repro on 2025/12/08 18:38
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+1b8918e16f1cb8a441e1@syzkaller.appspotmail.com
First crash: 301d, last: 3h10m
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/12/26 linux-6.6.y (ToT) 5fa4793a2d2d syz [report] WARNING in ext4_journal_check_start
2025/12/26 upstream (ToT) ccd1cdca5cd4 syz Didn't crash
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 WARNING in ext4_journal_check_start -1 1 727d 727d 0/3 auto-obsoleted due to no activity on 2025/01/15 23:20
upstream WARNING in ext4_journal_check_start (2) ext4 -1 syz, C inconclusive inconclusive 169 4h00m 717d 0/29 upstream: reported C repro on 2024/10/18 00:39
upstream WARNING in ext4_journal_check_start ext4 -1 syz 3 845d 894d 0/29 auto-obsoleted due to no activity on 2024/08/10 22:22
linux-6.1 WARNING in ext4_journal_check_start -1 1 11d 11d 0/3 upstream: reported on 2026/09/24 16:22
▶ ▼ Fix bisection attempts (1)
Created Duration User Patch Repo Result
2026/01/01 13:47 1h40m fix candidate upstream OK (0) job log

Sample crash report:
fscrypt: AES-256-CTS-CBC using implementation "cts-cbc-aes-aesni"
------------[ cut here ]------------
WARNING: CPU: 0 PID: 5935 at fs/ext4/ext4_jbd2.c:73 ext4_journal_check_start+0x1eb/0x250 fs/ext4/ext4_jbd2.c:73
Modules linked in:
CPU: 0 PID: 5935 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:ext4_journal_check_start+0x1eb/0x250 fs/ext4/ext4_jbd2.c:73
Code: 48 83 c4 08 41 bf e2 ff ff ff 44 89 f8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 c2 b8 59 ff 41 bf fb ff ff ff eb e5 e8 b5 b8 59 ff <0f> 0b eb d6 e8 ac b8 59 ff 0f 0b 43 80 7c 25 00 00 0f 85 0b ff ff
RSP: 0018:ffffc900047cf658 EFLAGS: 00010293
RAX: ffffffff822dd7fb RBX: ffff88814233e000 RCX: ffff888024fc8000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000bfe R08: ffff888141f38417 R09: 1ffff110283e7082
R10: dffffc0000000000 R11: ffffed10283e7083 R12: dffffc0000000000
R13: 1ffff11028467cc6 R14: ffff88814233e630 R15: 0000000000000001
FS:  00007f8e9514b6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9479f4a6b0 CR3: 000000007b991000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 __ext4_journal_start_sb+0x147/0x560 fs/ext4/ext4_jbd2.c:105
 __ext4_new_inode+0x13c7/0x3aa0 fs/ext4/ialloc.c:1091
 ext4_mkdir+0x40b/0xc90 fs/ext4/namei.c:3068
 vfs_mkdir+0x2a5/0x470 fs/namei.c:4168
 cachefiles_get_directory+0x231/0xa70 fs/cachefiles/namei.c:133
 cachefiles_add_cache+0xa88/0xd50 fs/cachefiles/cache.c:127
 cachefiles_daemon_write+0x5f9/0x6b0 fs/cachefiles/daemon.c:344
 vfs_write+0x299/0x9a0 fs/read_write.c:582
 ksys_write+0x151/0x260 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f8e9419e159
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:00007f8e9514b028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f8e94425fa0 RCX: 00007f8e9419e159
RDX: 0000000000000004 RSI: 0000200000000700 RDI: 0000000000000004
RBP: 00007f8e9423506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8e94426038 R14: 00007f8e94425fa0 R15: 00007ffd86704068
 </TASK>

Crashes (9):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/04 03:29 linux-6.6.y a91a6aa9253c 57bbd979 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-linux-6-6-kasan WARNING in ext4_journal_check_start
2025/12/08 18:38 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-6-kasan WARNING in ext4_journal_check_start
2026/10/05 17:20 linux-6.6.y a91a6aa9253c af63e995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in ext4_journal_check_start
2026/10/05 14:33 linux-6.6.y a91a6aa9253c af63e995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in ext4_journal_check_start
2026/10/05 14:33 linux-6.6.y a91a6aa9253c af63e995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in ext4_journal_check_start
2026/10/03 14:12 linux-6.6.y a91a6aa9253c 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in ext4_journal_check_start
2026/07/30 20:31 linux-6.6.y a1153c0deb44 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in ext4_journal_check_start
2026/07/04 16:42 linux-6.6.y da47cbc25466 fcece630 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in ext4_journal_check_start
2026/01/27 15:32 linux-6.6.y cbb31f77b879 9a514c2f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in ext4_journal_check_start
* Struck through repros no longer work on HEAD.