syzbot


possible deadlock in btrfs_commit_inode_delayed_inode

Status: upstream: reported on 2024/06/06 08:14
Subsystems: btrfs
[Documentation on labels]
Reported-by: syzbot+3dad89b3993a4b275e72@syzkaller.appspotmail.com
First crash: 12d, last: 13h59m
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [btrfs?] possible deadlock in btrfs_commit_inode_delayed_inode 0 (1) 2024/06/06 08:14

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.10.0-rc3-syzkaller-00044-g2ccbdf43d5e7 #0 Not tainted
------------------------------------------------------
kswapd0/112 is trying to acquire lock:
ffff888000d40610 (sb_internal#2){.+.+}-{0:0}, at: btrfs_commit_inode_delayed_inode+0x110/0x330 fs/btrfs/delayed-inode.c:1275

but task is already holding lock:
ffffffff8dd3aac0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x166/0x1970 mm/vmscan.c:6798

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (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]
       kmem_cache_alloc_lru_noprof+0x58/0x2f0 mm/slub.c:4020
       btrfs_alloc_inode+0x118/0xb20 fs/btrfs/inode.c:8411
       alloc_inode+0x5d/0x230 fs/inode.c:261
       iget5_locked fs/inode.c:1235 [inline]
       iget5_locked+0x1c9/0x2c0 fs/inode.c:1228
       btrfs_iget_locked fs/btrfs/inode.c:5590 [inline]
       btrfs_iget_path fs/btrfs/inode.c:5607 [inline]
       btrfs_iget+0xfb/0x230 fs/btrfs/inode.c:5636
       log_new_dir_dentries+0x372/0xdb0 fs/btrfs/tree-log.c:5502
       btrfs_log_all_parents fs/btrfs/tree-log.c:6836 [inline]
       btrfs_log_inode_parent+0x23ef/0x2a90 fs/btrfs/tree-log.c:7141
       btrfs_log_dentry_safe+0x59/0x80 fs/btrfs/tree-log.c:7180
       btrfs_sync_file+0x9c1/0xe10 fs/btrfs/file.c:1959
       vfs_fsync_range+0x141/0x230 fs/sync.c:188
       generic_write_sync include/linux/fs.h:2794 [inline]
       btrfs_do_write_iter+0x584/0x10c0 fs/btrfs/file.c:1705
       new_sync_write fs/read_write.c:497 [inline]
       vfs_write+0x6b6/0x1140 fs/read_write.c:590
       ksys_write+0x12f/0x260 fs/read_write.c:643
       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_extwriters){++++}-{0:0}:
       join_transaction+0x164/0xf40 fs/btrfs/transaction.c:315
       start_transaction+0x427/0x1a70 fs/btrfs/transaction.c:700
       btrfs_create_common+0x18b/0x270 fs/btrfs/inode.c:6566
       btrfs_create+0x114/0x160 fs/btrfs/inode.c:6612
       lookup_open.isra.0+0x10a1/0x13c0 fs/namei.c:3505
       open_last_lookups fs/namei.c:3574 [inline]
       path_openat+0x92f/0x29f0 fs/namei.c:3804
       do_filp_open+0x1dc/0x430 fs/namei.c:3834
       do_sys_openat2+0x17a/0x1e0 fs/open.c:1405
       do_sys_open fs/open.c:1420 [inline]
       __do_compat_sys_openat fs/open.c:1480 [inline]
       __se_compat_sys_openat fs/open.c:1478 [inline]
       __ia32_compat_sys_openat+0x16e/0x210 fs/open.c:1478
       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

-> #1 (btrfs_trans_num_writers){++++}-{0:0}:
       join_transaction+0x148/0xf40 fs/btrfs/transaction.c:314
       start_transaction+0x427/0x1a70 fs/btrfs/transaction.c:700
       btrfs_create_common+0x18b/0x270 fs/btrfs/inode.c:6566
       btrfs_create+0x114/0x160 fs/btrfs/inode.c:6612
       lookup_open.isra.0+0x10a1/0x13c0 fs/namei.c:3505
       open_last_lookups fs/namei.c:3574 [inline]
       path_openat+0x92f/0x29f0 fs/namei.c:3804
       do_filp_open+0x1dc/0x430 fs/namei.c:3834
       do_sys_openat2+0x17a/0x1e0 fs/open.c:1405
       do_sys_open fs/open.c:1420 [inline]
       __do_compat_sys_openat fs/open.c:1480 [inline]
       __se_compat_sys_openat fs/open.c:1478 [inline]
       __ia32_compat_sys_openat+0x16e/0x210 fs/open.c:1478
       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 (sb_internal#2){.+.+}-{0:0}:
       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
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1655 [inline]
       sb_start_intwrite include/linux/fs.h:1838 [inline]
       start_transaction+0xbc1/0x1a70 fs/btrfs/transaction.c:694
       btrfs_commit_inode_delayed_inode+0x110/0x330 fs/btrfs/delayed-inode.c:1275
       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_stack_put+0x60/0x90 fs/overlayfs/util.c:132
       ovl_destroy_inode+0xc6/0x190 fs/overlayfs/super.c:182
       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

other info that might help us debug this:

Chain exists of:
  sb_internal#2 --> btrfs_trans_num_extwriters --> fs_reclaim

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(fs_reclaim);
                               lock(btrfs_trans_num_extwriters);
                               lock(fs_reclaim);
  rlock(sb_internal#2);

 *** DEADLOCK ***

2 locks held by kswapd0/112:
 #0: ffffffff8dd3aac0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x166/0x1970 mm/vmscan.c:6798
 #1: ffff888000fae0e0 (&type->s_umount_key#108){++++}-{3:3}, at: super_trylock_shared fs/super.c:562 [inline]
 #1: ffff888000fae0e0 (&type->s_umount_key#108){++++}-{3:3}, at: super_cache_scan+0x96/0x550 fs/super.c:196

stack backtrace:
CPU: 0 PID: 112 Comm: kswapd0 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
 percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
 __sb_start_write include/linux/fs.h:1655 [inline]
 sb_start_intwrite include/linux/fs.h:1838 [inline]
 start_transaction+0xbc1/0x1a70 fs/btrfs/transaction.c:694
 btrfs_commit_inode_delayed_inode+0x110/0x330 fs/btrfs/delayed-inode.c:1275
 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_stack_put+0x60/0x90 fs/overlayfs/util.c:132
 ovl_destroy_inode+0xc6/0x190 fs/overlayfs/super.c:182
 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
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/06/14 14:29 upstream 2ccbdf43d5e7 c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in btrfs_commit_inode_delayed_inode
2024/06/04 11:16 upstream 2ab795141095 c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in btrfs_commit_inode_delayed_inode
2024/06/02 08:10 upstream ec9eeb89e60d c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in btrfs_commit_inode_delayed_inode
* Struck through repros no longer work on HEAD.