kernel BUG in balance_leaf (2)

Status: upstream: reported C repro on 2025/12/19 10:25
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+b017341f630a94cd6e1b@syzkaller.appspotmail.com
First crash: 229d, last: 207d
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/12/22 linux-6.1.y (ToT) 50cbba13faa2 C [report] kernel BUG in balance_leaf
2025/12/22 upstream (ToT) 9448598b22c5 C Didn't crash
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 kernel BUG in balance_leaf origin:lts-only -1 syz, C inconclusive 3 222d 222d 0/2 upstream: reported C repro on 2025/12/26 19:48
linux-4.14 kernel BUG in balance_leaf reiserfs -1 syz, C 1 1275d 1305d 0/1 upstream: reported C repro on 2023/01/08 11:53
upstream kernel BUG in balance_leaf fs -1 syz, C error done 16 958d 1309d 25/29 fixed on 2024/01/30 15:47
linux-5.15 kernel BUG in balance_leaf (2) origin:lts-only -1 syz, C error 3 42d 429d 0/3 upstream: reported C repro on 2025/06/02 02:17
linux-4.19 kernel BUG in balance_leaf reiserfs -1 syz, C error 1 1299d 1299d 0/1 upstream: reported C repro on 2023/01/13 23:48
linux-5.15 kernel BUG in balance_leaf -1 1 668d 668d 0/3 auto-obsoleted due to no activity on 2025/01/14 15:53
linux-6.1 kernel BUG in balance_leaf -1 4 1200d 1210d 0/3 auto-obsoleted due to no activity on 2023/08/21 17:28
▶ ▼ Fix bisection attempts (5)
Created Duration User Patch Repo Result
2026/07/18 21:11 2h08m fix candidate upstream OK (0) job log
2026/05/17 04:20 17m fix candidate upstream error job log
2026/03/25 13:51 1m fix candidate upstream error job log
2026/02/23 13:23 1m fix candidate upstream error job log
2026/01/23 19:20 3m fix candidate upstream error job log

Sample crash report:
REISERFS panic (device loop0): vs-12195 balance_leaf: CFR not initialized
------------[ cut here ]------------
kernel BUG at fs/reiserfs/prints.c:390!
Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 4503 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
pstate: 62400005 (nZCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : __reiserfs_panic+0x13c/0x140 fs/reiserfs/prints.c:384
lr : __reiserfs_panic+0x13c/0x140 fs/reiserfs/prints.c:384
sp : ffff800020de6520
x29: ffff800020de65c0 x28: ffff800020de6dc0 x27: ffff800020de6dd8
x26: ffff0000f2f40027 x25: dfff800000000000 x24: ffff800020de6f60
x23: ffff800020de6540 x22: ffff800011b5eba0 x21: ffff0000d4cc6000
x20: ffff800011b5eb80 x19: ffff800014770cbe x18: ffff800011a5bd40
x17: 6e6920746f6e2052 x16: ffff8000082d3a08 x15: 0000000000000000
x14: 00000000ffffffff x13: 0000000000000001 x12: 0000000000ff0100
x11: ff0080000830b6e8 x10: 0000000000000000 x9 : 8bc54311e7329100
x8 : 8bc54311e7329100 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff800020de5ff8 x4 : ffff800015134e00 x3 : ffff80000852f9b8
x2 : 0000000000000001 x1 : 0000000100000000 x0 : 0000000000000049
Call trace:
 __reiserfs_panic+0x13c/0x140 fs/reiserfs/prints.c:384
 balance_leaf+0xa0a8/0xd2f4 fs/reiserfs/do_balan.c:1439
 do_balance+0x260/0x774 fs/reiserfs/do_balan.c:1888
 reiserfs_paste_into_item+0x5b4/0x6d0 fs/reiserfs/stree.c:2159
 reiserfs_get_block+0x1444/0x3524 fs/reiserfs/inode.c:1069
 __block_write_begin_int+0x34c/0x13b8 fs/buffer.c:1991
 __block_write_begin+0x7c/0xa0 fs/buffer.c:2041
 reiserfs_write_begin+0x328/0x71c fs/reiserfs/inode.c:2775
 generic_perform_write+0x230/0x4e4 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+0x5ac/0x7c4 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]
 __arm64_sys_pwrite64+0x170/0x200 fs/read_write.c:706
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x138 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
Code: 912d80a5 911aa2a1 aa1303e4 97ffe397 (d4210000) 
---[ end trace 0000000000000000 ]---

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/19 15:08 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-1-kasan-arm64 kernel BUG in balance_leaf
2026/01/10 16:57 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 kernel BUG in balance_leaf
2026/01/01 14:52 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 kernel BUG in balance_leaf
2025/12/19 10:26 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 kernel BUG in balance_leaf
2025/12/19 10:24 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 kernel BUG in balance_leaf
* Struck through repros no longer work on HEAD.