[syzbot] [xfs?] possible deadlock in xfs_qm_dqget_cache_insert

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e5e038b7ae9d Merge tag 'fs_for_v6.9-rc1' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1629d9d1180000
kernel config: https://syzkaller.appspot.com/x/.config?x=6ce8d253b68e67fe
dashboard link: https://syzkaller.appspot.com/bug?extid=8fdff861a781522bda4d
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-e5e038b7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/82ab7eda09bc/vmlinux-e5e038b7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/bda17336e65d/bzImage-e5e038b7.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8fdff8...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.8.0-syzkaller-06619-ge5e038b7ae9d #0 Not tainted
------------------------------------------------------
syz-executor.0/10102 is trying to acquire lock:
ffffffff8d92fb40 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:303 [inline]
ffffffff8d92fb40 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:3746 [inline]
ffffffff8d92fb40 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:3827 [inline]
ffffffff8d92fb40 (fs_reclaim){+.+.}-{0:0}, at: kmem_cache_alloc+0x4f/0x320 mm/slub.c:3852

but task is already holding lock:
ffff88802712c958 (&qinf->qi_tree_lock){+.+.}-{3:3}, at: xfs_qm_dqget_cache_insert.constprop.0+0x2a/0x2c0 fs/xfs/xfs_dquot.c:825

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&qinf->qi_tree_lock){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:608 [inline]
__mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
xfs_qm_dqfree_one+0x6f/0x1a0 fs/xfs/xfs_qm.c:1654
xfs_qm_shrink_scan+0x25c/0x3f0 fs/xfs/xfs_qm.c:531
do_shrink_slab+0x44f/0x1160 mm/shrinker.c:435
shrink_slab+0x18a/0x1310 mm/shrinker.c:662
shrink_one+0x493/0x7b0 mm/vmscan.c:4767
shrink_many mm/vmscan.c:4828 [inline]
lru_gen_shrink_node mm/vmscan.c:4929 [inline]
shrink_node+0x2191/0x3770 mm/vmscan.c:5888
kswapd_shrink_node mm/vmscan.c:6696 [inline]
balance_pgdat+0x9d0/0x1a90 mm/vmscan.c:6886
kswapd+0x5c1/0xc10 mm/vmscan.c:7146
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:243

-> #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+0x1b1/0x540 kernel/locking/lockdep.c:5719
__fs_reclaim_acquire mm/page_alloc.c:3692 [inline]
fs_reclaim_acquire+0x102/0x150 mm/page_alloc.c:3706
might_alloc include/linux/sched/mm.h:303 [inline]
slab_pre_alloc_hook mm/slub.c:3746 [inline]
slab_alloc_node mm/slub.c:3827 [inline]
kmem_cache_alloc+0x4f/0x320 mm/slub.c:3852
radix_tree_node_alloc.constprop.0+0x7c/0x350 lib/radix-tree.c:276
radix_tree_extend+0x1a2/0x4d0 lib/radix-tree.c:425
__radix_tree_create lib/radix-tree.c:613 [inline]
radix_tree_insert+0x499/0x630 lib/radix-tree.c:712
xfs_qm_dqget_cache_insert.constprop.0+0x38/0x2c0 fs/xfs/xfs_dquot.c:826
xfs_qm_dqget+0x182/0x4a0 fs/xfs/xfs_dquot.c:901
xfs_qm_vop_dqalloc+0x49a/0xe10 fs/xfs/xfs_qm.c:1755
xfs_create+0x422/0x1140 fs/xfs/xfs_inode.c:1041
xfs_generic_create+0x631/0x7c0 fs/xfs/xfs_iops.c:199
lookup_open.isra.0+0x10a1/0x13c0 fs/namei.c:3497
open_last_lookups fs/namei.c:3566 [inline]
path_openat+0x92f/0x2990 fs/namei.c:3796
do_filp_open+0x1dc/0x430 fs/namei.c:3826
do_sys_openat2+0x17a/0x1e0 fs/open.c:1406
do_sys_open fs/open.c:1421 [inline]
__do_compat_sys_openat fs/open.c:1481 [inline]
__se_compat_sys_openat fs/open.c:1479 [inline]
__ia32_compat_sys_openat+0x16e/0x210 fs/open.c:1479
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0x7a/0x120 arch/x86/entry/common.c:321
do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:346
entry_SYSENTER_compat_after_hwframe+0x7a/0x84

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&qinf->qi_tree_lock);
lock(fs_reclaim);
lock(&qinf->qi_tree_lock);
lock(fs_reclaim);

*** DEADLOCK ***

3 locks held by syz-executor.0/10102:
#0: ffff88801e4f0420 (sb_writers#21){.+.+}-{0:0}, at: open_last_lookups fs/namei.c:3555 [inline]
#0: ffff88801e4f0420 (sb_writers#21){.+.+}-{0:0}, at: path_openat+0x19a7/0x2990 fs/namei.c:3796
#1: ffff88804c060338 (&inode->i_sb->s_type->i_mutex_dir_key){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:793 [inline]
#1: ffff88804c060338 (&inode->i_sb->s_type->i_mutex_dir_key){+.+.}-{3:3}, at: open_last_lookups fs/namei.c:3563 [inline]
#1: ffff88804c060338 (&inode->i_sb->s_type->i_mutex_dir_key){+.+.}-{3:3}, at: path_openat+0x8c7/0x2990 fs/namei.c:3796
#2: ffff88802712c958 (&qinf->qi_tree_lock){+.+.}-{3:3}, at: xfs_qm_dqget_cache_insert.constprop.0+0x2a/0x2c0 fs/xfs/xfs_dquot.c:825

stack backtrace:
CPU: 3 PID: 10102 Comm: syz-executor.0 Not tainted 6.8.0-syzkaller-06619-ge5e038b7ae9d #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+0x1b1/0x540 kernel/locking/lockdep.c:5719
__fs_reclaim_acquire mm/page_alloc.c:3692 [inline]
fs_reclaim_acquire+0x102/0x150 mm/page_alloc.c:3706
might_alloc include/linux/sched/mm.h:303 [inline]
slab_pre_alloc_hook mm/slub.c:3746 [inline]
slab_alloc_node mm/slub.c:3827 [inline]
kmem_cache_alloc+0x4f/0x320 mm/slub.c:3852
radix_tree_node_alloc.constprop.0+0x7c/0x350 lib/radix-tree.c:276
radix_tree_extend+0x1a2/0x4d0 lib/radix-tree.c:425
__radix_tree_create lib/radix-tree.c:613 [inline]
radix_tree_insert+0x499/0x630 lib/radix-tree.c:712
xfs_qm_dqget_cache_insert.constprop.0+0x38/0x2c0 fs/xfs/xfs_dquot.c:826
xfs_qm_dqget+0x182/0x4a0 fs/xfs/xfs_dquot.c:901
xfs_qm_vop_dqalloc+0x49a/0xe10 fs/xfs/xfs_qm.c:1755
xfs_create+0x422/0x1140 fs/xfs/xfs_inode.c:1041
xfs_generic_create+0x631/0x7c0 fs/xfs/xfs_iops.c:199
lookup_open.isra.0+0x10a1/0x13c0 fs/namei.c:3497
open_last_lookups fs/namei.c:3566 [inline]
path_openat+0x92f/0x2990 fs/namei.c:3796
do_filp_open+0x1dc/0x430 fs/namei.c:3826
do_sys_openat2+0x17a/0x1e0 fs/open.c:1406
do_sys_open fs/open.c:1421 [inline]
__do_compat_sys_openat fs/open.c:1481 [inline]
__se_compat_sys_openat fs/open.c:1479 [inline]
__ia32_compat_sys_openat+0x16e/0x210 fs/open.c:1479
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0x7a/0x120 arch/x86/entry/common.c:321
do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:346
entry_SYSENTER_compat_after_hwframe+0x7a/0x84
RIP: 0023:0xf7328579
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:00000000f5f225ac EFLAGS: 00000292 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00000000ffffff9c RCX: 00000000200002c0
RDX: 000000000000275a RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
syz-executor.0 (10102) used greatest stack depth: 20032 bytes left
----------------
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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