syzbot


kernel panic: bch_dev->ref underflow, last put: bch2_trigger_alloc

Status: fixed on 2024/06/11 03:41
Subsystems: bcachefs
[Documentation on labels]
Reported-by: syzbot+5c7f715a7107a608a544@syzkaller.appspotmail.com
Fix commit: 9667214b30ef bcachefs: Fix ref in trans_mark_dev_sbs() error path
First crash: 36d, last: 25d
Cause bisection: introduced by (bisect log) :
commit 552aa5486579c18b4f8e7ca03ef88fa573c517b5
Author: Kent Overstreet <kent.overstreet@linux.dev>
Date: Fri May 3 22:07:40 2024 +0000

  bcachefs: Debug asserts for ca->ref

Crash: kernel panic: bch_dev->ref underflow, last put: bch2_get_next_dev (log)
Repro: C syz .config
  
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [bcachefs?] kernel panic: bch_dev->ref underflow, last put: bch2_trigger_alloc 0 (1) 2024/05/13 10:35

Sample crash report:
bcachefs (loop0): mounting version 1.7: mi_btree_bitmap opts=metadata_checksum=none,data_checksum=none,nojournal_transaction_names
bcachefs (loop0): recovering from clean shutdown, journal seq 8
bcachefs (loop0): alloc_read... done
bcachefs (loop0): stripes_read... done
bcachefs (loop0): snapshots_read... done
bucket 0:4 gen 0 different types of data in same bucket: btree, sb
while marking sb, shutting down
bcachefs (loop0): inconsistency detected - emergency read only at journal seq 8
bcachefs (loop0): bch2_trans_mark_dev_sb(): error EIO
Kernel panic - not syncing: bch_dev->ref underflow, last put: __bch2_dev_put fs/bcachefs/sb-members.h:110 [inline]
Kernel panic - not syncing: bch_dev->ref underflow, last put: bch2_dev_put fs/bcachefs/sb-members.h:121 [inline]
Kernel panic - not syncing: bch_dev->ref underflow, last put: bch2_trigger_alloc+0x2934/0x3b90 fs/bcachefs/alloc_background.c:913
CPU: 1 PID: 5093 Comm: syz-executor498 Not tainted 6.9.0-rc7-next-20240510-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 panic+0x349/0x860 kernel/panic.c:347
 __bch2_dev_put fs/bcachefs/sb-members.h:109 [inline]
 bch2_dev_put fs/bcachefs/sb-members.h:121 [inline]
 bch2_trans_mark_dev_sbs_flags+0xaa7/0xab0 fs/bcachefs/buckets.c:1467
 bch2_run_recovery_pass+0xf0/0x1e0 fs/bcachefs/recovery_passes.c:182
 bch2_run_recovery_passes+0x19e/0x820 fs/bcachefs/recovery_passes.c:225
 bch2_fs_recovery+0x2370/0x3700 fs/bcachefs/recovery.c:804
 bch2_fs_start+0x356/0x5b0 fs/bcachefs/super.c:1031
 bch2_fs_open+0xa8d/0xdf0 fs/bcachefs/super.c:2123
 bch2_mount+0x71d/0x1320 fs/bcachefs/fs.c:1917
 legacy_get_tree+0xee/0x190 fs/fs_context.c:662
 vfs_get_tree+0x90/0x2a0 fs/super.c:1780
 do_new_mount+0x2be/0xb40 fs/namespace.c:3352
 do_mount fs/namespace.c:3692 [inline]
 __do_sys_mount fs/namespace.c:3898 [inline]
 __se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3875
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7facf885c8fa
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 5e 04 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe54cb8d38 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffe54cb8d50 RCX: 00007facf885c8fa
RDX: 0000000020005b00 RSI: 0000000020005b40 RDI: 00007ffe54cb8d50
RBP: 0000000000000004 R08: 00007ffe54cb8d90 R09: 0000000000005b4c
R10: 0000000000000000 R11: 0000000000000282 R12: 0000000000000000
R13: 00007ffe54cb8d90 R14: 0000000000000003 R15: 0000000001000000
 </TASK>
Kernel Offset: disabled
Rebooting in 86400 seconds..

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/05/13 02:50 linux-next 75fa778d74b7 9026e142 .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-linux-next-kasan-gce-root kernel panic: bch_dev->ref underflow, last put: bch2_trigger_alloc
2024/05/24 12:52 upstream 8f6a15f095a6 8f98448e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root kernel panic: bch_dev->ref underflow, last put: bch2_trigger_alloc
2024/05/23 09:28 upstream 8f6a15f095a6 4d098039 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root kernel panic: bch_dev->ref underflow, last put: bch2_trigger_alloc
2024/05/23 05:14 upstream 8f6a15f095a6 4d098039 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root kernel panic: bch_dev->ref underflow, last put: bch2_trigger_alloc
2024/05/20 00:01 linux-next c75962170e49 c0f1611a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root kernel panic: bch_dev->ref underflow, last put: bch2_trigger_alloc
2024/05/13 02:27 linux-next 75fa778d74b7 9026e142 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root kernel panic: bch_dev->ref underflow, last put: bch2_trigger_alloc
* Struck through repros no longer work on HEAD.