[syzbot] [xfs?] possible deadlock in xfs_ilock (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 72374d71c315 Merge tag 'pull-sysfs-annotation-fix' of git:..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10639da3180000
kernel config: https://syzkaller.appspot.com/x/.config?x=43fc40c117780e9b
dashboard link: https://syzkaller.appspot.com/bug?extid=c6d7bff58a2218f14632
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-72374d71.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0ea69c8c9aa6/vmlinux-72374d71.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fcfb8e2b6b87/bzImage-72374d71.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c6d7bf...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.9.0-rc3-syzkaller-00399-g72374d71c315 #0 Not tainted
------------------------------------------------------
syz-executor.0/6233 is trying to acquire lock:
ffffffff8d9373c0 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:312 [inline]
ffffffff8d9373c0 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:3746 [inline]
ffffffff8d9373c0 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:3827 [inline]
ffffffff8d9373c0 (fs_reclaim){+.+.}-{0:0}, at: __do_kmalloc_node mm/slub.c:3965 [inline]
ffffffff8d9373c0 (fs_reclaim){+.+.}-{0:0}, at: __kmalloc+0xb5/0x440 mm/slub.c:3979

but task is already holding lock:
ffff888028971858 (&xfs_dir_ilock_class){++++}-{3:3}, at: xfs_ilock+0x16a/0x420 fs/xfs/xfs_inode.c:208

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&xfs_dir_ilock_class){++++}-{3:3}:
down_write_nested+0x3d/0x50 kernel/locking/rwsem.c:1695
xfs_ilock+0x2ef/0x420 fs/xfs/xfs_inode.c:206
xfs_reclaim_inode fs/xfs/xfs_icache.c:945 [inline]
xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1631 [inline]
xfs_icwalk_ag+0xca6/0x1780 fs/xfs/xfs_icache.c:1713
xfs_icwalk+0x57/0x100 fs/xfs/xfs_icache.c:1762
xfs_reclaim_inodes_nr+0x182/0x250 fs/xfs/xfs_icache.c:1011
super_cache_scan+0x409/0x550 fs/super.c:227
do_shrink_slab+0x44f/0x11c0 mm/shrinker.c:435
shrink_slab+0x18a/0x1310 mm/shrinker.c:662
shrink_one+0x493/0x7c0 mm/vmscan.c:4774
shrink_many mm/vmscan.c:4835 [inline]
lru_gen_shrink_node+0x89f/0x1750 mm/vmscan.c:4935
shrink_node mm/vmscan.c:5894 [inline]
kswapd_shrink_node mm/vmscan.c:6704 [inline]
balance_pgdat+0x10d1/0x1a10 mm/vmscan.c:6895
kswapd+0x5ea/0xbf0 mm/vmscan.c:7164
kthread+0x2c1/0x3a0 kernel/kthread.c:388
ret_from_fork+0x45/0x80 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 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
__fs_reclaim_acquire mm/page_alloc.c:3698 [inline]
fs_reclaim_acquire+0x102/0x160 mm/page_alloc.c:3712
might_alloc include/linux/sched/mm.h:312 [inline]
slab_pre_alloc_hook mm/slub.c:3746 [inline]
slab_alloc_node mm/slub.c:3827 [inline]
__do_kmalloc_node mm/slub.c:3965 [inline]
__kmalloc+0xb5/0x440 mm/slub.c:3979
kmalloc include/linux/slab.h:632 [inline]
xfs_attr_shortform_list fs/xfs/xfs_attr_list.c:115 [inline]
xfs_attr_list_ilocked+0x8b7/0x1740 fs/xfs/xfs_attr_list.c:527
xfs_attr_list+0x1f9/0x2b0 fs/xfs/xfs_attr_list.c:547
xfs_vn_listxattr+0x11f/0x1c0 fs/xfs/xfs_xattr.c:314
vfs_listxattr+0xb7/0x140 fs/xattr.c:493
listxattr+0x69/0x190 fs/xattr.c:840
path_listxattr+0xc3/0x160 fs/xattr.c:864
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:321
do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:346
entry_SYSENTER_compat_after_hwframe+0x84/0x8e

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.0/6233:
#0: ffff888028971858 (&xfs_dir_ilock_class){++++}-{3:3}, at: xfs_ilock+0x16a/0x420 fs/xfs/xfs_inode.c:208

stack backtrace:
CPU: 2 PID: 6233 Comm: syz-executor.0 Not tainted 6.9.0-rc3-syzkaller-00399-g72374d71c315 #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
__fs_reclaim_acquire mm/page_alloc.c:3698 [inline]
fs_reclaim_acquire+0x102/0x160 mm/page_alloc.c:3712
might_alloc include/linux/sched/mm.h:312 [inline]
slab_pre_alloc_hook mm/slub.c:3746 [inline]
slab_alloc_node mm/slub.c:3827 [inline]
__do_kmalloc_node mm/slub.c:3965 [inline]
__kmalloc+0xb5/0x440 mm/slub.c:3979
kmalloc include/linux/slab.h:632 [inline]
xfs_attr_shortform_list fs/xfs/xfs_attr_list.c:115 [inline]
xfs_attr_list_ilocked+0x8b7/0x1740 fs/xfs/xfs_attr_list.c:527
xfs_attr_list+0x1f9/0x2b0 fs/xfs/xfs_attr_list.c:547
xfs_vn_listxattr+0x11f/0x1c0 fs/xfs/xfs_xattr.c:314
vfs_listxattr+0xb7/0x140 fs/xattr.c:493
listxattr+0x69/0x190 fs/xattr.c:840
path_listxattr+0xc3/0x160 fs/xattr.c:864
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:321
do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:346
entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf728a579
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:00000000f5e7c5ac EFLAGS: 00000292 ORIG_RAX: 00000000000000e9
RAX: ffffffffffffffda RBX: 00000000200000c0 RCX: 0000000000000000
RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
----------------
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


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