syzbot


possible deadlock in xfs_ilock_attr_map_shared

Status: upstream: reported on 2024/05/23 01:43
Subsystems: xfs
[Documentation on labels]
Reported-by: syzbot+069cc167ecbee6e3e91a@syzkaller.appspotmail.com
First crash: 30d, last: 14d
Discussions (2)
Title Replies (including bot) Last reply
[syzbot] Monthly xfs report (May 2024) 0 (1) 2024/05/31 06:48
[syzbot] [xfs?] possible deadlock in xfs_ilock_attr_map_shared 0 (1) 2024/05/23 01:43

Sample crash report:
XFS (loop4): Ending clean mount
XFS (loop4): Quotacheck needed: Please wait.
XFS (loop4): Quotacheck: Done.
======================================================
WARNING: possible circular locking dependency detected
6.10.0-rc2-syzkaller-00010-g2ab795141095 #0 Not tainted
------------------------------------------------------
syz-executor.4/23651 is trying to acquire lock:
ffffffff8e42b240 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:334 [inline]
ffffffff8e42b240 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:3890 [inline]
ffffffff8e42b240 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:3980 [inline]
ffffffff8e42b240 (fs_reclaim){+.+.}-{0:0}, at: __do_kmalloc_node mm/slub.c:4120 [inline]
ffffffff8e42b240 (fs_reclaim){+.+.}-{0:0}, at: __kmalloc_noprof+0xa9/0x400 mm/slub.c:4134

but task is already holding lock:
ffff88806a8c5658 (&xfs_dir_ilock_class){++++}-{3:3}, at: xfs_ilock_attr_map_shared+0x8c/0xc0 fs/xfs/xfs_inode.c:127

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&xfs_dir_ilock_class){++++}-{3:3}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       down_write_nested+0x3d/0x50 kernel/locking/rwsem.c:1695
       xfs_reclaim_inode fs/xfs/xfs_icache.c:943 [inline]
       xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1629 [inline]
       xfs_icwalk_ag+0x120e/0x1ad0 fs/xfs/xfs_icache.c:1711
       xfs_icwalk fs/xfs/xfs_icache.c:1760 [inline]
       xfs_reclaim_inodes_nr+0x257/0x360 fs/xfs/xfs_icache.c:1009
       super_cache_scan+0x411/0x4b0 fs/super.c:227
       do_shrink_slab+0x707/0x1160 mm/shrinker.c:435
       shrink_slab+0x1094/0x14d0 mm/shrinker.c:662
       shrink_one+0x453/0x880 mm/vmscan.c:4790
       shrink_many mm/vmscan.c:4851 [inline]
       lru_gen_shrink_node mm/vmscan.c:4951 [inline]
       shrink_node+0x37eb/0x3fe0 mm/vmscan.c:5910
       kswapd_shrink_node mm/vmscan.c:6720 [inline]
       balance_pgdat mm/vmscan.c:6911 [inline]
       kswapd+0x1882/0x3700 mm/vmscan.c:7180
       kthread+0x2f2/0x390 kernel/kthread.c:389
       ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #0 (fs_reclaim){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3869
       __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __fs_reclaim_acquire mm/page_alloc.c:3783 [inline]
       fs_reclaim_acquire+0x88/0x140 mm/page_alloc.c:3797
       might_alloc include/linux/sched/mm.h:334 [inline]
       slab_pre_alloc_hook mm/slub.c:3890 [inline]
       slab_alloc_node mm/slub.c:3980 [inline]
       __do_kmalloc_node mm/slub.c:4120 [inline]
       __kmalloc_noprof+0xa9/0x400 mm/slub.c:4134
       kmalloc_noprof include/linux/slab.h:664 [inline]
       xfs_attr_shortform_list+0x753/0x1900 fs/xfs/xfs_attr_list.c:117
       xfs_attr_list+0x1d0/0x270 fs/xfs/xfs_attr_list.c:595
       xfs_vn_listxattr+0x1d2/0x2c0 fs/xfs/xfs_xattr.c:324
       vfs_listxattr fs/xattr.c:493 [inline]
       listxattr+0x109/0x290 fs/xattr.c:840
       path_listxattr fs/xattr.c:864 [inline]
       __do_sys_llistxattr fs/xattr.c:882 [inline]
       __se_sys_llistxattr fs/xattr.c:879 [inline]
       __x64_sys_llistxattr+0x173/0x230 fs/xattr.c:879
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(&xfs_dir_ilock_class);
                               lock(fs_reclaim);
                               lock(&xfs_dir_ilock_class);
  lock(fs_reclaim);

 *** DEADLOCK ***

1 lock held by syz-executor.4/23651:
 #0: ffff88806a8c5658 (&xfs_dir_ilock_class){++++}-{3:3}, at: xfs_ilock_attr_map_shared+0x8c/0xc0 fs/xfs/xfs_inode.c:127

stack backtrace:
CPU: 0 PID: 23651 Comm: syz-executor.4 Not tainted 6.10.0-rc2-syzkaller-00010-g2ab795141095 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 check_noncircular+0x36a/0x4a0 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+0x18e0/0x5900 kernel/locking/lockdep.c:3869
 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
 __fs_reclaim_acquire mm/page_alloc.c:3783 [inline]
 fs_reclaim_acquire+0x88/0x140 mm/page_alloc.c:3797
 might_alloc include/linux/sched/mm.h:334 [inline]
 slab_pre_alloc_hook mm/slub.c:3890 [inline]
 slab_alloc_node mm/slub.c:3980 [inline]
 __do_kmalloc_node mm/slub.c:4120 [inline]
 __kmalloc_noprof+0xa9/0x400 mm/slub.c:4134
 kmalloc_noprof include/linux/slab.h:664 [inline]
 xfs_attr_shortform_list+0x753/0x1900 fs/xfs/xfs_attr_list.c:117
 xfs_attr_list+0x1d0/0x270 fs/xfs/xfs_attr_list.c:595
 xfs_vn_listxattr+0x1d2/0x2c0 fs/xfs/xfs_xattr.c:324
 vfs_listxattr fs/xattr.c:493 [inline]
 listxattr+0x109/0x290 fs/xattr.c:840
 path_listxattr fs/xattr.c:864 [inline]
 __do_sys_llistxattr fs/xattr.c:882 [inline]
 __se_sys_llistxattr fs/xattr.c:879 [inline]
 __x64_sys_llistxattr+0x173/0x230 fs/xattr.c:879
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd14b67cf69
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fd14c3810c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000c3
RAX: ffffffffffffffda RBX: 00007fd14b7b3fa0 RCX: 00007fd14b67cf69
RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000020000280
RBP: 00007fd14b6da706 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007fd14b7b3fa0 R15: 00007ffd171e06a8
 </TASK>
XFS (loop4): Unmounting Filesystem bfdc47fc-10d8-4eed-a562-11a831b3f791

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/06/04 08:51 upstream 2ab795141095 a1feae05 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in xfs_ilock_attr_map_shared
2024/05/19 01:36 upstream 4b377b4868ef c0f1611a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in xfs_ilock_attr_map_shared
2024/06/04 05:47 linux-next d97496ca23a2 a1feae05 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in xfs_ilock_attr_map_shared
* Struck through repros no longer work on HEAD.