syzbot


possible deadlock in btrfs_quota_enable

Status: upstream: reported on 2024/06/02 20:43
Subsystems: btrfs
[Documentation on labels]
Reported-by: syzbot+bec38eba8bd1096de8d2@syzkaller.appspotmail.com
First crash: 19d, last: 1d11h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [btrfs?] possible deadlock in btrfs_quota_enable 0 (1) 2024/06/02 20:43

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.10.0-rc3-syzkaller-00044-g2ccbdf43d5e7 #0 Not tainted
------------------------------------------------------
syz-executor.2/9288 is trying to acquire lock:
ffff888054679870 (&fs_info->qgroup_ioctl_lock){+.+.}-{3:3}, at: btrfs_quota_enable+0x3a1/0x1ef0 fs/btrfs/qgroup.c:1086

but task is already holding lock:
ffff88805467a418 (btrfs_trans_num_extwriters){++++}-{0:0}, at: join_transaction+0x137/0xf40 fs/btrfs/transaction.c:314

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (btrfs_trans_num_extwriters){++++}-{0:0}:
       join_transaction+0x164/0xf40 fs/btrfs/transaction.c:315
       start_transaction+0x427/0x1a70 fs/btrfs/transaction.c:700
       btrfs_defrag_root+0x12a/0x1a90 fs/btrfs/defrag.c:581
       btrfs_ioctl_defrag+0x2e4/0x3c0 fs/btrfs/ioctl.c:2629
       btrfs_ioctl+0x405b/0x8290 fs/btrfs/ioctl.c:4689
       __do_compat_sys_ioctl+0x2c3/0x330 fs/ioctl.c:1007
       do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
       __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
       do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
       entry_SYSENTER_compat_after_hwframe+0x84/0x8e

-> #2 (btrfs_trans_num_writers){++++}-{0:0}:
       __lock_release kernel/locking/lockdep.c:5468 [inline]
       lock_release+0x33e/0x6c0 kernel/locking/lockdep.c:5774
       percpu_up_read include/linux/percpu-rwsem.h:99 [inline]
       __sb_end_write include/linux/fs.h:1650 [inline]
       sb_end_intwrite include/linux/fs.h:1767 [inline]
       __btrfs_end_transaction+0x5ca/0x920 fs/btrfs/transaction.c:1071
       btrfs_commit_inode_delayed_inode+0x228/0x330 fs/btrfs/delayed-inode.c:1301
       btrfs_evict_inode+0x960/0xe80 fs/btrfs/inode.c:5291
       evict+0x2ed/0x6c0 fs/inode.c:667
       iput_final fs/inode.c:1741 [inline]
       iput.part.0+0x5a8/0x7f0 fs/inode.c:1767
       iput+0x5c/0x80 fs/inode.c:1757
       dentry_unlink_inode+0x295/0x480 fs/dcache.c:400
       __dentry_kill+0x1d0/0x600 fs/dcache.c:603
       dput.part.0+0x4b1/0x9b0 fs/dcache.c:845
       dput+0x1f/0x30 fs/dcache.c:835
       ovl_destroy_inode+0x3e/0x190 fs/overlayfs/super.c:181
       destroy_inode+0xc4/0x1b0 fs/inode.c:311
       iput_final fs/inode.c:1741 [inline]
       iput.part.0+0x5a8/0x7f0 fs/inode.c:1767
       iput+0x5c/0x80 fs/inode.c:1757
       dentry_unlink_inode+0x295/0x480 fs/dcache.c:400
       __dentry_kill+0x1d0/0x600 fs/dcache.c:603
       shrink_kill fs/dcache.c:1048 [inline]
       shrink_dentry_list+0x140/0x5d0 fs/dcache.c:1075
       prune_dcache_sb+0xeb/0x150 fs/dcache.c:1156
       super_cache_scan+0x32a/0x550 fs/super.c:221
       do_shrink_slab+0x44f/0x11c0 mm/shrinker.c:435
       shrink_slab_memcg mm/shrinker.c:548 [inline]
       shrink_slab+0xa87/0x1310 mm/shrinker.c:626
       shrink_one+0x493/0x7c0 mm/vmscan.c:4790
       shrink_many mm/vmscan.c:4851 [inline]
       lru_gen_shrink_node+0x89f/0x1750 mm/vmscan.c:4951
       shrink_node mm/vmscan.c:5910 [inline]
       kswapd_shrink_node mm/vmscan.c:6720 [inline]
       balance_pgdat+0x1105/0x1970 mm/vmscan.c:6911
       kswapd+0x5ea/0xbf0 mm/vmscan.c:7180
       kthread+0x2c1/0x3a0 kernel/kthread.c:389
       ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #1 (fs_reclaim){+.+.}-{0:0}:
       __fs_reclaim_acquire mm/page_alloc.c:3801 [inline]
       fs_reclaim_acquire+0x102/0x160 mm/page_alloc.c:3815
       might_alloc include/linux/sched/mm.h:334 [inline]
       slab_pre_alloc_hook mm/slub.c:3891 [inline]
       slab_alloc_node mm/slub.c:3981 [inline]
       kmalloc_trace_noprof+0x51/0x310 mm/slub.c:4148
       kmalloc_noprof include/linux/slab.h:660 [inline]
       ulist_alloc+0x77/0x1c0 fs/btrfs/ulist.c:98
       btrfs_quota_enable+0x342/0x1ef0 fs/btrfs/qgroup.c:1051
       btrfs_ioctl_quota_ctl fs/btrfs/ioctl.c:3765 [inline]
       btrfs_ioctl+0x6af4/0x8290 fs/btrfs/ioctl.c:4762
       __do_compat_sys_ioctl+0x2c3/0x330 fs/ioctl.c:1007
       do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
       __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
       do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
       entry_SYSENTER_compat_after_hwframe+0x84/0x8e

-> #0 (&fs_info->qgroup_ioctl_lock){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137
       lock_acquire kernel/locking/lockdep.c:5754 [inline]
       lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
       btrfs_quota_enable+0x3a1/0x1ef0 fs/btrfs/qgroup.c:1086
       btrfs_ioctl_quota_ctl fs/btrfs/ioctl.c:3765 [inline]
       btrfs_ioctl+0x6af4/0x8290 fs/btrfs/ioctl.c:4762
       __do_compat_sys_ioctl+0x2c3/0x330 fs/ioctl.c:1007
       do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
       __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
       do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
       entry_SYSENTER_compat_after_hwframe+0x84/0x8e

other info that might help us debug this:

Chain exists of:
  &fs_info->qgroup_ioctl_lock --> btrfs_trans_num_writers --> btrfs_trans_num_extwriters

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(btrfs_trans_num_extwriters);
                               lock(btrfs_trans_num_writers);
                               lock(btrfs_trans_num_extwriters);
  lock(&fs_info->qgroup_ioctl_lock);

 *** DEADLOCK ***

5 locks held by syz-executor.2/9288:
 #0: ffff88805499e420 (sb_writers#15){.+.+}-{0:0}, at: btrfs_ioctl_quota_ctl fs/btrfs/ioctl.c:3751 [inline]
 #0: ffff88805499e420 (sb_writers#15){.+.+}-{0:0}, at: btrfs_ioctl+0x20a0/0x8290 fs/btrfs/ioctl.c:4762
 #1: ffff888054678bd0 (&fs_info->subvol_sem){+.+.}-{3:3}, at: btrfs_ioctl_quota_ctl fs/btrfs/ioctl.c:3764 [inline]
 #1: ffff888054678bd0 (&fs_info->subvol_sem){+.+.}-{3:3}, at: btrfs_ioctl+0x6ae9/0x8290 fs/btrfs/ioctl.c:4762
 #2: ffff88805499e610 (sb_internal#2){.+.+}-{0:0}, at: btrfs_quota_enable+0x392/0x1ef0 fs/btrfs/qgroup.c:1084
 #3: ffff88805467a3f0 (btrfs_trans_num_writers){++++}-{0:0}, at: join_transaction+0x137/0xf40 fs/btrfs/transaction.c:314
 #4: ffff88805467a418 (btrfs_trans_num_extwriters){++++}-{0:0}, at: join_transaction+0x137/0xf40 fs/btrfs/transaction.c:314

stack backtrace:
CPU: 1 PID: 9288 Comm: syz-executor.2 Not tainted 6.10.0-rc3-syzkaller-00044-g2ccbdf43d5e7 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137
 lock_acquire kernel/locking/lockdep.c:5754 [inline]
 lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719
 __mutex_lock_common kernel/locking/mutex.c:608 [inline]
 __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
 btrfs_quota_enable+0x3a1/0x1ef0 fs/btrfs/qgroup.c:1086
 btrfs_ioctl_quota_ctl fs/btrfs/ioctl.c:3765 [inline]
 btrfs_ioctl+0x6af4/0x8290 fs/btrfs/ioctl.c:4762
 __do_compat_sys_ioctl+0x2c3/0x330 fs/ioctl.c:1007
 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
 __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf733e579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f5f305ac EFLAGS: 00000292 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00000000c0109428
RDX: 0000000020000040 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
BTRFS info (device loop2): setting incompat feature flag for SIMPLE_QUOTA (0x10000)
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	10 06                	adc    %al,(%rsi)
   2:	03 74 b4 01          	add    0x1(%rsp,%rsi,4),%esi
   6:	10 07                	adc    %al,(%rdi)
   8:	03 74 b0 01          	add    0x1(%rax,%rsi,4),%esi
   c:	10 08                	adc    %cl,(%rax)
   e:	03 74 d8 01          	add    0x1(%rax,%rbx,8),%esi
  1e:	00 51 52             	add    %dl,0x52(%rcx)
  21:	55                   	push   %rbp
  22:	89 e5                	mov    %esp,%ebp
  24:	0f 34                	sysenter
  26:	cd 80                	int    $0x80
* 28:	5d                   	pop    %rbp <-- trapping instruction
  29:	5a                   	pop    %rdx
  2a:	59                   	pop    %rcx
  2b:	c3                   	ret
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	90                   	nop
  2f:	90                   	nop
  30:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi
  37:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/06/17 01:03 upstream 2ccbdf43d5e7 c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in btrfs_quota_enable
2024/06/12 19:20 upstream cea2a26553ac c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in btrfs_quota_enable
2024/06/12 19:09 upstream cea2a26553ac c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in btrfs_quota_enable
2024/06/12 03:15 upstream 2ef5971ff345 c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in btrfs_quota_enable
2024/06/06 06:35 upstream 2df0193e62cf c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in btrfs_quota_enable
2024/05/29 20:39 upstream 4a4be1ad3a6e c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in btrfs_quota_enable
* Struck through repros no longer work on HEAD.