[syzbot] [bcachefs?] possible deadlock in trans_set_locked

From: syzbot
Date: Fri Nov 29 2024 - 12:09:42 EST

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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@xxxxxxxxxxxxxxxxxxxxxxxxx

======================================================
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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Next message: Casey Schaufler: "Re: [GIT PULL] execve updates for v6.13-rc1 (take 2)"
Previous message: Duje Mihanović: " Re: [PATCH next] clk: mmp: pxa1908-apbc: Fix NULL vs IS_ERR() check in probe"
Next in thread: Kent Overstreet: "Re: [syzbot] [bcachefs?] possible deadlock in trans_set_locked"
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