WARNING in bfs_get_block

Status: upstream: reported C repro on 2026/05/07 22:51
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+615f4f94914be8224a24@syzkaller.appspotmail.com
First crash: 116d, last: 5h08m
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2026/08/22 linux-6.1.y (ToT) 7e6e67054721 C [report] WARNING in bfs_get_block
2026/08/22 upstream (ToT) 26260251022f C Didn't crash
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in bfs_get_block prio:low bfs -1 syz, C error 298 20h15m 155d 0/29 upstream: reported C repro on 2026/03/30 05:05
linux-6.6 WARNING in bfs_get_block origin:upstream -1 syz, C error 8 65d 130d 0/2 upstream: reported C repro on 2026/04/24 05:14
▶ ▼ Fix bisection attempts (1)
Created Duration User Patch Repo Result
2026/06/26 10:05 2h26m bisect fix linux-6.1.y OK (0) job log log

Sample crash report:
loop3: detected capacity change from 0 to 64
------------[ cut here ]------------
WARNING: CPU: 1 PID: 4571 at fs/buffer.c:1081 mark_buffer_dirty+0x328/0x5c0 fs/buffer.c:1081
Modules linked in:
CPU: 1 PID: 4571 Comm: syz.3.20 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
pstate: 82400005 (Nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : mark_buffer_dirty+0x328/0x5c0 fs/buffer.c:1081
lr : mark_buffer_dirty+0x328/0x5c0 fs/buffer.c:1081
sp : ffff8000214075f0
x29: ffff8000214075f0 x28: ffff0000d8315e80 x27: ffff0000d831cae0
x26: ffff0000d28b6018 x25: ffff0000d28b6160 x24: 000000000000000a
x23: ffff0000f5e46600 x22: 0000000000000200 x21: ffff0000ef9b6430
x20: 0000000000000010 x19: ffff0000d8315e80 x18: 0000000000000000
x17: 0000000000000000 x16: ffff8000082dcf38 x15: 0000000000000000
x14: 0000000000000001 x13: 1fffe0001b062bd0 x12: 0000000000000000
x11: ff00800008a9d648 x10: 0000000000000000 x9 : ffff800008a9d648
x8 : ffff0000d3758000 x7 : 0000000000000000 x6 : 0000000000000000
x5 : ffff0000f5e46800 x4 : ffff0000f5e56400 x3 : ffff800008a9d350
x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
 mark_buffer_dirty+0x328/0x5c0 fs/buffer.c:1081
 bfs_move_block fs/bfs/file.c:43 [inline]
 bfs_move_blocks fs/bfs/file.c:56 [inline]
 bfs_get_block+0x468/0x95c fs/bfs/file.c:125
 __block_write_begin_int+0x3d8/0x13c0 fs/buffer.c:1991
 __block_write_begin fs/buffer.c:2041 [inline]
 block_write_begin+0x98/0x11c fs/buffer.c:2102
 bfs_write_begin+0x48/0xec fs/bfs/file.c:177
 generic_perform_write+0x240/0x508 mm/filemap.c:3862
 __generic_file_write_iter+0x130/0x250 mm/filemap.c:3960
 generic_file_write_iter+0xb4/0x2b0 mm/filemap.c:3989
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x3c8/0x7c8 fs/read_write.c:584
 ksys_write+0x12c/0x228 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.c:646
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
irq event stamp: 4358
hardirqs last  enabled at (4357): [<ffff800008a9cd3c>] bh_lru_install fs/buffer.c:1258 [inline]
hardirqs last  enabled at (4357): [<ffff800008a9cd3c>] __find_get_block+0xbd8/0xde4 fs/buffer.c:1309
hardirqs last disabled at (4358): [<ffff800011b8b0d4>] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:405
softirqs last  enabled at (4090): [<ffff800008031254>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32
softirqs last disabled at (4088): [<ffff800008031220>] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19
---[ end trace 0000000000000000 ]---

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/19 10:41 linux-6.1.y 090666d3cc90 72524a66 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-1-kasan-arm64 WARNING in bfs_get_block
2026/07/19 07:56 linux-6.1.y 090666d3cc90 72524a66 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-1-kasan-arm64 WARNING in bfs_get_block
2026/07/19 05:59 linux-6.1.y 090666d3cc90 72524a66 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-1-kasan-arm64 WARNING in bfs_get_block
2026/05/27 09:36 linux-6.1.y dcbcab9d7079 2b01f00e .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-1-kasan-arm64 WARNING in bfs_get_block
2026/09/01 16:43 linux-6.1.y d64a499eea6b 587f6b29 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in bfs_get_block
2026/05/07 22:50 linux-6.1.y 4931e0e1673d cbf9e0fc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in bfs_get_block
* Struck through repros no longer work on HEAD.