Message-ID: <6749f54c.050a0220.253251.00bc.GAE@google.com>
Date: Fri, 29 Nov 2024 09:09:32 -0800
From: syzbot <syzbot+78f4eb354f5ca6c1e6eb@...kaller.appspotmail.com>
To: kent.overstreet@...ux.dev, linux-bcachefs@...r.kernel.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [bcachefs?] possible deadlock in trans_set_locked

Hello,

syzbot found the following issue on:

HEAD commit:    7b1d1d4cfac0 Merge remote-tracking branch 'iommu/arm/smmu'..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=17d6af78580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9bc44a6de1ceb5d6
dashboard link: https://syzkaller.appspot.com/bug?extid=78f4eb354f5ca6c1e6eb
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=107bdf5f980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13ae49e8580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4d4a0162c7c3/disk-7b1d1d4c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a8c47a4be472/vmlinux-7b1d1d4c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0e173b91f83e/Image-7b1d1d4c.gz.xz
mounted in repro #1: https://storage.googleapis.com/syzbot-assets/5ab7b24d2900/mount_0.gz
mounted in repro #2: https://storage.googleapis.com/syzbot-assets/fbfbb60588c1/mount_2.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+78f4eb354f5ca6c1e6eb@...kaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.12.0-syzkaller-g7b1d1d4cfac0 #0 Not tainted
------------------------------------------------------
syz-executor203/6432 is trying to acquire lock:
ffff0000da100128 (bcachefs_btree){+.+.}-{0:0}, at: trans_set_locked+0x5c/0x21c fs/bcachefs/btree_locking.h:193

but task is already holding lock:
ffff0000dc661548 (&c->fsck_error_msgs_lock){+.+.}-{3:3}, at: __bch2_fsck_err+0x344/0x2544 fs/bcachefs/error.c:282

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&c->fsck_error_msgs_lock){+.+.}-{3:3}:
       __mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:608
       __mutex_lock kernel/locking/mutex.c:752 [inline]
       mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:804
       __bch2_fsck_err+0x344/0x2544 fs/bcachefs/error.c:282
       bch2_check_alloc_hole_freespace+0x5fc/0xd74 fs/bcachefs/alloc_background.c:1278
       bch2_check_alloc_info+0x1174/0x26f8 fs/bcachefs/alloc_background.c:1547
       bch2_run_recovery_pass+0xe4/0x1d4 fs/bcachefs/recovery_passes.c:191
       bch2_run_online_recovery_passes+0xa4/0x174 fs/bcachefs/recovery_passes.c:212
       bch2_fsck_online_thread_fn+0x150/0x3e8 fs/bcachefs/chardev.c:799
       thread_with_stdio_fn+0x64/0x134 fs/bcachefs/thread_with_file.c:298
       kthread+0x288/0x310 kernel/kthread.c:389
       ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862

-> #0 (bcachefs_btree){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain kernel/locking/lockdep.c:3904 [inline]
       __lock_acquire+0x33f8/0x77c8 kernel/locking/lockdep.c:5202
       lock_acquire+0x240/0x728 kernel/locking/lockdep.c:5825
       trans_set_locked+0x88/0x21c fs/bcachefs/btree_locking.h:194
       __bch2_trans_relock+0x2a0/0x394 fs/bcachefs/btree_locking.c:785
       bch2_trans_relock+0x24/0x34 fs/bcachefs/btree_locking.c:793
       __bch2_fsck_err+0x1664/0x2544 fs/bcachefs/error.c:363
       bch2_check_alloc_hole_freespace+0x5fc/0xd74 fs/bcachefs/alloc_background.c:1278
       bch2_check_alloc_info+0x1174/0x26f8 fs/bcachefs/alloc_background.c:1547
       bch2_run_recovery_pass+0xe4/0x1d4 fs/bcachefs/recovery_passes.c:191
       bch2_run_online_recovery_passes+0xa4/0x174 fs/bcachefs/recovery_passes.c:212
       bch2_fsck_online_thread_fn+0x150/0x3e8 fs/bcachefs/chardev.c:799
       thread_with_stdio_fn+0x64/0x134 fs/bcachefs/thread_with_file.c:298
       kthread+0x288/0x310 kernel/kthread.c:389
       ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&c->fsck_error_msgs_lock);
                               lock(bcachefs_btree);
                               lock(&c->fsck_error_msgs_lock);
  lock(bcachefs_btree);

 *** DEADLOCK ***

3 locks held by syz-executor203/6432:
 #0: ffff0000dc600278 (&c->state_lock){++++}-{3:3}, at: bch2_run_online_recovery_passes+0x3c/0x174 fs/bcachefs/recovery_passes.c:204
 #1: ffff0000dc604398 (&c->btree_trans_barrier){.+.+}-{0:0}, at: srcu_lock_acquire+0x18/0x54 include/linux/srcu.h:150
 #2: ffff0000dc661548 (&c->fsck_error_msgs_lock){+.+.}-{3:3}, at: __bch2_fsck_err+0x344/0x2544 fs/bcachefs/error.c:282

stack backtrace:
CPU: 1 UID: 0 PID: 6432 Comm: syz-executor203 Not tainted 6.12.0-syzkaller-g7b1d1d4cfac0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:484 (C)
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:120
 dump_stack+0x1c/0x28 lib/dump_stack.c:129
 print_circular_bug+0x154/0x1c0 kernel/locking/lockdep.c:2074
 check_noncircular+0x310/0x404 kernel/locking/lockdep.c:2206
 check_prev_add kernel/locking/lockdep.c:3161 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain kernel/locking/lockdep.c:3904 [inline]
 __lock_acquire+0x33f8/0x77c8 kernel/locking/lockdep.c:5202
 lock_acquire+0x240/0x728 kernel/locking/lockdep.c:5825
 trans_set_locked+0x88/0x21c fs/bcachefs/btree_locking.h:194
 __bch2_trans_relock+0x2a0/0x394 fs/bcachefs/btree_locking.c:785
 bch2_trans_relock+0x24/0x34 fs/bcachefs/btree_locking.c:793
 __bch2_fsck_err+0x1664/0x2544 fs/bcachefs/error.c:363
 bch2_check_alloc_hole_freespace+0x5fc/0xd74 fs/bcachefs/alloc_background.c:1278
 bch2_check_alloc_info+0x1174/0x26f8 fs/bcachefs/alloc_background.c:1547
 bch2_run_recovery_pass+0xe4/0x1d4 fs/bcachefs/recovery_passes.c:191
 bch2_run_online_recovery_passes+0xa4/0x174 fs/bcachefs/recovery_passes.c:212
 bch2_fsck_online_thread_fn+0x150/0x3e8 fs/bcachefs/chardev.c:799
 thread_with_stdio_fn+0x64/0x134 fs/bcachefs/thread_with_file.c:298
 kthread+0x288/0x310 kernel/kthread.c:389
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862


---
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