linux-kernel - Re: [syzbot] [bcachefs?] possible deadlock in __bch2_fsck

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Message-ID: <682c0765.a00a0220.7a43a.0083.GAE@google.com>
Date: Mon, 19 May 2025 21:39:01 -0700
From: syzbot <syzbot+2c3ef91c9523c3d1a25c@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org, mmpgouride@...il.com, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [bcachefs?] possible deadlock in __bch2_fsck_err (2)

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in __init_work

ODEBUG: object 000000002b138723 is on stack 00000000dac59cbe, but NOT annotated.
------------[ cut here ]------------
WARNING: CPU: 0 PID: 7170 at lib/debugobjects.c:655 debug_object_is_on_stack lib/debugobjects.c:-1 [inline]
WARNING: CPU: 0 PID: 7170 at lib/debugobjects.c:655 lookup_object_or_alloc lib/debugobjects.c:688 [inline]
WARNING: CPU: 0 PID: 7170 at lib/debugobjects.c:655 __debug_object_init+0x364/0x40c lib/debugobjects.c:743
Modules linked in:
CPU: 0 UID: 0 PID: 7170 Comm: bch-copygc/loop Not tainted 6.15.0-rc4-syzkaller-00229-gd27565abe66b #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : debug_object_is_on_stack lib/debugobjects.c:-1 [inline]
pc : lookup_object_or_alloc lib/debugobjects.c:688 [inline]
pc : __debug_object_init+0x364/0x40c lib/debugobjects.c:743
lr : debug_object_is_on_stack lib/debugobjects.c:-1 [inline]
lr : lookup_object_or_alloc lib/debugobjects.c:688 [inline]
lr : __debug_object_init+0x364/0x40c lib/debugobjects.c:743
sp : ffff80009bef7700
x29: ffff80009bef7700 x28: 0000000000000000 x27: dfff800000000000
x26: ffff80009729c000 x25: ffff0000e8709ea0 x24: 0000000000000000
x23: ffff0000dd671460 x22: 0000000000000000 x21: ffff80009715dcc0
x20: ffff80008ae5d7c0 x19: ffff80009bef7bb0 x18: 00000000ffffffff
x17: ffff800092f28000 x16: ffff80008adb72d4 x15: 0000000000000001
x14: 1ffff000137dee4c x13: 0000000000000000 x12: 0000000000000000
x11: ffff7000137dee4d x10: 0000000000ff0100 x9 : 47869bb3fecc8f00
x8 : 47869bb3fecc8f00 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff80009bef7098 x4 : ffff80008f404fc0 x3 : ffff800082fbada4
x2 : 0000000000000001 x1 : 0000000100000001 x0 : 0000000000000050
Call trace:
 debug_object_is_on_stack lib/debugobjects.c:-1 [inline] (P)
 lookup_object_or_alloc lib/debugobjects.c:688 [inline] (P)
 __debug_object_init+0x364/0x40c lib/debugobjects.c:743 (P)
 debug_object_init+0x20/0x2c lib/debugobjects.c:779
 __init_work+0x58/0x68 kernel/workqueue.c:677
 rhashtable_init_noprof+0x734/0xa10 lib/rhashtable.c:1085
 bch2_copygc_thread+0xec/0xd40 fs/bcachefs/movinggc.c:355
 kthread+0x5fc/0x75c kernel/kthread.c:464
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:847
irq event stamp: 22
hardirqs last  enabled at (21): [<ffff800083df1134>] get_random_u32+0x2d4/0x540 drivers/char/random.c:553
hardirqs last disabled at (22): [<ffff80008add7b2c>] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:108 [inline]
hardirqs last disabled at (22): [<ffff80008add7b2c>] _raw_spin_lock_irqsave+0x2c/0x7c kernel/locking/spinlock.c:162
softirqs last  enabled at (0): [<ffff8000803a4fb0>] copy_process+0x112c/0x318c kernel/fork.c:2374
softirqs last disabled at (0): [<0000000000000000>] 0x0
---[ end trace 0000000000000000 ]---


Tested on:

commit:         d27565ab bcachefs: Fix possible console lock involved ..
git tree:       https://github.com/alanskind/bcachefs
console output: https://syzkaller.appspot.com/x/log.txt?x=162861f4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1358066360ea77fb
dashboard link: https://syzkaller.appspot.com/bug?extid=2c3ef91c9523c3d1a25c
compiler:       Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
userspace arch: arm64

Note: no patches were applied.