syzbot


kernel BUG in ext4_do_writepages

Status: upstream: reported C repro on 2025/07/07 19:42
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+203932ca69a3bb6e336e@syzkaller.appspotmail.com
First crash: 42d, last: 9d02h
Bug presence (1)
Date Name Commit Repro Result
2025/07/07 upstream (ToT) d7b8f8e20813 C [report] kernel BUG in ext4_do_writepages
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream kernel BUG in ext4_do_writepages ext4 -1 C error 2547 22h05m 975d 0/29 upstream: reported C repro on 2022/12/17 20:23
Fix bisection attempts (1)
Created Duration User Patch Repo Result
2025/08/09 23:46 2h34m bisect fix linux-6.6.y OK (0) job log log

Sample crash report:
------------[ cut here ]------------
kernel BUG at fs/ext4/inode.c:2603!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 1141 Comm: kworker/u4:11 Not tainted 6.6.96-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: writeback wb_workfn (flush-7:0)
RIP: 0010:ext4_do_writepages+0x38cd/0x38d0 fs/ext4/inode.c:2602
Code: c1 03 38 c1 0f 8c 7a fd ff ff 4c 89 e7 e8 5b af ac ff e9 6d fd ff ff e8 91 00 54 ff 0f 0b e8 8a 00 54 ff 0f 0b e8 83 00 54 ff <0f> 0b 90 66 0f 1f 00 55 41 57 41 56 41 54 53 48 89 fb 49 bf 00 00
RSP: 0018:ffffc900047ceec0 EFLAGS: 00010293
RAX: ffffffff823195dd RBX: 0000004210000000 RCX: ffff888023cc9e00
RDX: 0000000000000000 RSI: 0000004000000000 RDI: 0000000000000000
RBP: ffffc900047cf230 R08: ffff88805e3f1457 R09: 1ffff1100bc7e28a
R10: dffffc0000000000 R11: ffffed100bc7e28b R12: 0000000000000001
R13: ffff88805e3f16b0 R14: 0000004000000000 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7d64d71d60 CR3: 000000002faae000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ext4_writepages+0x1a8/0x2f0 fs/ext4/inode.c:2807
 do_writepages+0x3a2/0x600 mm/page-writeback.c:2575
 __writeback_single_inode+0x153/0xee0 fs/fs-writeback.c:1625
 writeback_sb_inodes+0x77c/0xef0 fs/fs-writeback.c:1916
 wb_writeback+0x450/0xba0 fs/fs-writeback.c:2095
 wb_do_writeback fs/fs-writeback.c:2242 [inline]
 wb_workfn+0x3ff/0xe20 fs/fs-writeback.c:2282
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ext4_do_writepages+0x38cd/0x38d0 fs/ext4/inode.c:2602
Code: c1 03 38 c1 0f 8c 7a fd ff ff 4c 89 e7 e8 5b af ac ff e9 6d fd ff ff e8 91 00 54 ff 0f 0b e8 8a 00 54 ff 0f 0b e8 83 00 54 ff <0f> 0b 90 66 0f 1f 00 55 41 57 41 56 41 54 53 48 89 fb 49 bf 00 00
RSP: 0018:ffffc900047ceec0 EFLAGS: 00010293
RAX: ffffffff823195dd RBX: 0000004210000000 RCX: ffff888023cc9e00
RDX: 0000000000000000 RSI: 0000004000000000 RDI: 0000000000000000
RBP: ffffc900047cf230 R08: ffff88805e3f1457 R09: 1ffff1100bc7e28a
R10: dffffc0000000000 R11: ffffed100bc7e28b R12: 0000000000000001
R13: ffff88805e3f16b0 R14: 0000004000000000 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007faa8bc75000 CR3: 000000002ac1e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/07 19:41 linux-6.6.y a5df3a702b2c 4f67c4ae .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-6-kasan kernel BUG in ext4_do_writepages
2025/07/10 06:52 linux-6.6.y a5df3a702b2c 956bd956 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan kernel BUG in ext4_do_writepages
2025/07/09 14:42 linux-6.6.y a5df3a702b2c f4e5e155 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan kernel BUG in ext4_do_writepages
2025/07/09 14:42 linux-6.6.y a5df3a702b2c f4e5e155 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan kernel BUG in ext4_do_writepages
2025/07/09 01:36 linux-6.6.y a5df3a702b2c 4d9fdfa4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan kernel BUG in ext4_do_writepages
2025/07/09 01:36 linux-6.6.y a5df3a702b2c 4d9fdfa4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan kernel BUG in ext4_do_writepages
* Struck through repros no longer work on HEAD.