syzbot


possible deadlock in ext4_inline_data_truncate (2)

Status: upstream: reported on 2024/06/02 13:53
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+8bf80f09a0a9767b4308@syzkaller.appspotmail.com
First crash: 16d, last: 1d13h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [ext4?] possible deadlock in ext4_inline_data_truncate (2) 0 (1) 2024/06/02 13:53
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in ext4_inline_data_truncate ext4 1 454d 450d 0/27 auto-obsoleted due to no activity on 2023/07/17 03:13

Sample crash report:
WARNING: possible circular locking dependency detected
6.10.0-rc3-syzkaller-00044-g2ccbdf43d5e7 #0 Not tainted
------------------------------------------------------
syz-executor.3/5975 is trying to acquire lock:
ffff888028fceec8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
ffff888028fceec8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_inline_data_truncate+0x1af/0xc80 fs/ext4/inline.c:1915

but task is already holding lock:
ffff8880284bc610 (sb_internal){.+.+}-{0:0}, at: evict+0x2ed/0x6c0 fs/inode.c:667

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (sb_internal){.+.+}-{0:0}:
       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]
       ext4_evict_inode+0xd7b/0x17d0 fs/ext4/inode.c:212
       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
       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]
       __do_kmalloc_node mm/slub.c:4121 [inline]
       __kmalloc_node_noprof+0xbb/0x450 mm/slub.c:4129
       kmalloc_node_noprof include/linux/slab.h:681 [inline]
       kvmalloc_node_noprof+0x9d/0x1a0 mm/util.c:634
       ext4_xattr_inode_cache_find fs/ext4/xattr.c:1535 [inline]
       ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1581 [inline]
       ext4_xattr_inode_lookup_create+0x4e8/0x1910 fs/ext4/xattr.c:1568
       ext4_xattr_block_set+0x77a/0x3090 fs/ext4/xattr.c:1910
       ext4_xattr_move_to_block fs/ext4/xattr.c:2663 [inline]
       ext4_xattr_make_inode_space fs/ext4/xattr.c:2738 [inline]
       ext4_expand_extra_isize_ea+0xf57/0x1990 fs/ext4/xattr.c:2830
       __ext4_expand_extra_isize+0x322/0x450 fs/ext4/inode.c:5782
       ext4_try_to_expand_extra_isize fs/ext4/inode.c:5825 [inline]
       __ext4_mark_inode_dirty+0x55a/0x890 fs/ext4/inode.c:5903
       __ext4_unlink+0x630/0xcb0 fs/ext4/namei.c:3292
       ext4_unlink+0x422/0x610 fs/ext4/namei.c:3321
       vfs_unlink+0x2fb/0x9b0 fs/namei.c:4343
       do_unlinkat+0x5c0/0x750 fs/namei.c:4407
       __do_sys_unlink fs/namei.c:4455 [inline]
       __se_sys_unlink fs/namei.c:4453 [inline]
       __ia32_sys_unlink+0xc6/0x110 fs/namei.c:4453
       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 (&ei->xattr_sem){++++}-{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
       down_write+0x3a/0x50 kernel/locking/rwsem.c:1579
       ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
       ext4_inline_data_truncate+0x1af/0xc80 fs/ext4/inline.c:1915
       ext4_truncate+0x990/0x1400 fs/ext4/inode.c:4095
       ext4_evict_inode+0x7ae/0x17d0 fs/ext4/inode.c:258
       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
       do_unlinkat+0x613/0x750 fs/namei.c:4414
       __do_sys_unlink fs/namei.c:4455 [inline]
       __se_sys_unlink fs/namei.c:4453 [inline]
       __ia32_sys_unlink+0xc6/0x110 fs/namei.c:4453
       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:
  &ei->xattr_sem --> fs_reclaim --> sb_internal

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(sb_internal);
                               lock(fs_reclaim);
                               lock(sb_internal);
  lock(&ei->xattr_sem);

 *** DEADLOCK ***

2 locks held by syz-executor.3/5975:
 #0: ffff8880284bc420 (sb_writers#4){.+.+}-{0:0}, at: do_unlinkat+0x1d3/0x750 fs/namei.c:4390
 #1: ffff8880284bc610 (sb_internal){.+.+}-{0:0}, at: evict+0x2ed/0x6c0 fs/inode.c:667

stack backtrace:
CPU: 1 PID: 5975 Comm: syz-executor.3 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
 down_write+0x3a/0x50 kernel/locking/rwsem.c:1579
 ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
 ext4_inline_data_truncate+0x1af/0xc80 fs/ext4/inline.c:1915
 ext4_truncate+0x990/0x1400 fs/ext4/inode.c:4095
 ext4_evict_inode+0x7ae/0x17d0 fs/ext4/inode.c:258
 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
 do_unlinkat+0x613/0x750 fs/namei.c:4414
 __do_sys_unlink fs/namei.c:4455 [inline]
 __se_sys_unlink fs/namei.c:4453 [inline]
 __ia32_sys_unlink+0xc6/0x110 fs/namei.c:4453
 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: 0023:0xf7343579
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:00000000ffdd4b3c EFLAGS: 00000292 ORIG_RAX: 000000000000000a
RAX: ffffffffffffffda RBX: 00000000ffdd4be0 RCX: 0000000000008000
RDX: 00000000f7499ff4 RSI: 0000000000000000 RDI: 00000000ffdd5c80
RBP: 00000000ffdd4be0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
EXT4-fs (loop3): unmounting filesystem 00000000-0000-0000-0000-000000000000.
----------------
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 (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/06/13 16:32 upstream 2ccbdf43d5e7 c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in ext4_inline_data_truncate
2024/05/29 13:49 upstream e0cce98fe279 c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in ext4_inline_data_truncate
* Struck through repros no longer work on HEAD.