[syzbot] [xfs?] possible deadlock in xfs_qm_dquot_isolate

syzbot
2024-05-15T03:32:24Z

Hello,

syzbot found the following issue on:

HEAD commit: f4345f05c0df Merge tag 'block-6.9-20240510' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10c35598980000
kernel config: https://syzkaller.appspot.com/x/.config?x=a450595960709c8
dashboard link: https://syzkaller.appspot.com/bug?extid=6d8d043596bb844b6947
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-f4345f05.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5e01373e68f5/vmlinux-f4345f05.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dd55eb82d95f/bzImage-f4345f05.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6d8d043596bb844b6947@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.9.0-rc7-syzkaller-00136-gf4345f05c0df #0 Not tainted
------------------------------------------------------
syz-executor.3/11149 is trying to acquire lock:
ffffffff8d937180 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:312 [inline]
ffffffff8d937180 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:3752 [inline]
ffffffff8d937180 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:3833 [inline]
ffffffff8d937180 (fs_reclaim){+.+.}-{0:0}, at: kmalloc_trace+0x51/0x340 mm/slub.c:3998

but task is already holding lock:
ffff88806900e5a8 (&dqp->q_qlock){+.+.}-{3:3}, at: xfs_dqlock_nowait fs/xfs/xfs_dquot.h:120 [inline]
ffff88806900e5a8 (&dqp->q_qlock){+.+.}-{3:3}, at: xfs_qm_dquot_isolate+0x85/0x1420 fs/xfs/xfs_qm.c:423

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (&dqp->q_qlock){+.+.}-{3:3}:
__lock_release kernel/locking/lockdep.c:5468 [inline]
lock_release+0x33e/0x6c0 kernel/locking/lockdep.c:5774
__mutex_unlock_slowpath+0xa3/0x650 kernel/locking/mutex.c:912
xfs_qm_dqget_cache_lookup+0x428/0x880 fs/xfs/xfs_dquot.c:802
xfs_qm_dqget_inode+0x1e7/0x6d0 fs/xfs/xfs_dquot.c:994
xfs_qm_dqattach_one+0x26f/0x590 fs/xfs/xfs_qm.c:278
xfs_qm_dqattach_locked+0x226/0x2d0 fs/xfs/xfs_qm.c:329
xfs_qm_vop_dqalloc+0x344/0xe40 fs/xfs/xfs_qm.c:1710
xfs_create+0x422/0x1170 fs/xfs/xfs_inode.c:1041
xfs_generic_create+0x631/0x7c0 fs/xfs/xfs_iops.c:199
vfs_mkdir+0x57d/0x820 fs/namei.c:4123
do_mkdirat+0x301/0x3a0 fs/namei.c:4146
__do_sys_mkdir fs/namei.c:4166 [inline]
__se_sys_mkdir fs/namei.c:4164 [inline]
__ia32_sys_mkdir+0xf0/0x140 fs/namei.c:4164
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0x75/0x120 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 (&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:3752 [inline]
slab_alloc_node mm/slub.c:3833 [inline]
kmalloc_trace+0x51/0x340 mm/slub.c:3998
kmalloc include/linux/slab.h:628 [inline]
add_stack_record_to_list mm/page_owner.c:177 [inline]
inc_stack_record_count mm/page_owner.c:219 [inline]
__set_page_owner+0x517/0x7a0 mm/page_owner.c:334
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x2d4/0x350 mm/page_alloc.c:1534
prep_new_page mm/page_alloc.c:1541 [inline]
get_page_from_freelist+0xa28/0x3780 mm/page_alloc.c:3317
__alloc_pages+0x22b/0x2460 mm/page_alloc.c:4575
__alloc_pages_bulk+0x742/0x14f0 mm/page_alloc.c:4523
alloc_pages_bulk_array include/linux/gfp.h:202 [inline]
xfs_buf_alloc_pages+0x20f/0x9d0 fs/xfs/xfs_buf.c:398
xfs_buf_find_insert fs/xfs/xfs_buf.c:650 [inline]
xfs_buf_get_map+0x1e69/0x30d0 fs/xfs/xfs_buf.c:755
xfs_buf_read_map+0xd2/0xb40 fs/xfs/xfs_buf.c:860
xfs_trans_read_buf_map+0x352/0x990 fs/xfs/xfs_trans_buf.c:289
xfs_trans_read_buf fs/xfs/xfs_trans.h:210 [inline]
xfs_qm_dqflush+0x224/0x1470 fs/xfs/xfs_dquot.c:1271
xfs_qm_dquot_isolate+0xc8f/0x1420 fs/xfs/xfs_qm.c:465
__list_lru_walk_one+0x19f/0x690 mm/list_lru.c:218
list_lru_walk_one+0xac/0xf0 mm/list_lru.c:266
list_lru_shrink_walk include/linux/list_lru.h:228 [inline]
xfs_qm_shrink_scan+0x1fc/0x3f0 fs/xfs/xfs_qm.c:519
do_shrink_slab+0x44f/0x11c0 mm/shrinker.c:435
shrink_slab+0x18a/0x1310 mm/shrinker.c:662
drop_slab_node mm/vmscan.c:393 [inline]
drop_slab+0x14c/0x2c0 mm/vmscan.c:411
drop_caches_sysctl_handler+0x171/0x190 fs/drop_caches.c:68
proc_sys_call_handler+0x4cc/0x6f0 fs/proc/proc_sysctl.c:595
call_write_iter include/linux/fs.h:2110 [inline]
iter_file_splice_write+0x906/0x10b0 fs/splice.c:743
do_splice_from fs/splice.c:941 [inline]
direct_splice_actor+0x19b/0x6d0 fs/splice.c:1164
splice_direct_to_actor+0x346/0xa40 fs/splice.c:1108
do_splice_direct_actor fs/splice.c:1207 [inline]
do_splice_direct+0x17e/0x250 fs/splice.c:1233
do_sendfile+0xaa8/0xdb0 fs/read_write.c:1295
__do_compat_sys_sendfile fs/read_write.c:1377 [inline]
__se_compat_sys_sendfile fs/read_write.c:1366 [inline]
__ia32_compat_sys_sendfile+0x163/0x230 fs/read_write.c:1366
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0x75/0x120 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:
fs_reclaim --> &xfs_dir_ilock_class --> &dqp->q_qlock

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&dqp->q_qlock);
lock(&xfs_dir_ilock_class);
lock(&dqp->q_qlock);
lock(fs_reclaim);

*** DEADLOCK ***

2 locks held by syz-executor.3/11149:
#0: ffff888021f1e420 (sb_writers#3){.+.+}-{0:0}, at: splice_direct_to_actor+0x346/0xa40 fs/splice.c:1108
#1: ffff88806900e5a8 (&dqp->q_qlock){+.+.}-{3:3}, at: xfs_dqlock_nowait fs/xfs/xfs_dquot.h:120 [inline]
#1: ffff88806900e5a8 (&dqp->q_qlock){+.+.}-{3:3}, at: xfs_qm_dquot_isolate+0x85/0x1420 fs/xfs/xfs_qm.c:423

stack backtrace:
CPU: 0 PID: 11149 Comm: syz-executor.3 Not tainted 6.9.0-rc7-syzkaller-00136-gf4345f05c0df #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:3752 [inline]
slab_alloc_node mm/slub.c:3833 [inline]
kmalloc_trace+0x51/0x340 mm/slub.c:3998
kmalloc include/linux/slab.h:628 [inline]
add_stack_record_to_list mm/page_owner.c:177 [inline]
inc_stack_record_count mm/page_owner.c:219 [inline]
__set_page_owner+0x517/0x7a0 mm/page_owner.c:334
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x2d4/0x350 mm/page_alloc.c:1534
prep_new_page mm/page_alloc.c:1541 [inline]
get_page_from_freelist+0xa28/0x3780 mm/page_alloc.c:3317
__alloc_pages+0x22b/0x2460 mm/page_alloc.c:4575
__alloc_pages_bulk+0x742/0x14f0 mm/page_alloc.c:4523
alloc_pages_bulk_array include/linux/gfp.h:202 [inline]
xfs_buf_alloc_pages+0x20f/0x9d0 fs/xfs/xfs_buf.c:398
xfs_buf_find_insert fs/xfs/xfs_buf.c:650 [inline]
xfs_buf_get_map+0x1e69/0x30d0 fs/xfs/xfs_buf.c:755
xfs_buf_read_map+0xd2/0xb40 fs/xfs/xfs_buf.c:860
xfs_trans_read_buf_map+0x352/0x990 fs/xfs/xfs_trans_buf.c:289
xfs_trans_read_buf fs/xfs/xfs_trans.h:210 [inline]
xfs_qm_dqflush+0x224/0x1470 fs/xfs/xfs_dquot.c:1271
xfs_qm_dquot_isolate+0xc8f/0x1420 fs/xfs/xfs_qm.c:465
__list_lru_walk_one+0x19f/0x690 mm/list_lru.c:218
list_lru_walk_one+0xac/0xf0 mm/list_lru.c:266
list_lru_shrink_walk include/linux/list_lru.h:228 [inline]
xfs_qm_shrink_scan+0x1fc/0x3f0 fs/xfs/xfs_qm.c:519
do_shrink_slab+0x44f/0x11c0 mm/shrinker.c:435
shrink_slab+0x18a/0x1310 mm/shrinker.c:662
drop_slab_node mm/vmscan.c:393 [inline]
drop_slab+0x14c/0x2c0 mm/vmscan.c:411
drop_caches_sysctl_handler+0x171/0x190 fs/drop_caches.c:68
proc_sys_call_handler+0x4cc/0x6f0 fs/proc/proc_sysctl.c:595
call_write_iter include/linux/fs.h:2110 [inline]
iter_file_splice_write+0x906/0x10b0 fs/splice.c:743
do_splice_from fs/splice.c:941 [inline]
direct_splice_actor+0x19b/0x6d0 fs/splice.c:1164
splice_direct_to_actor+0x346/0xa40 fs/splice.c:1108
do_splice_direct_actor fs/splice.c:1207 [inline]
do_splice_direct+0x17e/0x250 fs/splice.c:1233
do_sendfile+0xaa8/0xdb0 fs/read_write.c:1295
__do_compat_sys_sendfile fs/read_write.c:1377 [inline]
__se_compat_sys_sendfile fs/read_write.c:1366 [inline]
__ia32_compat_sys_sendfile+0x163/0x230 fs/read_write.c:1366
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0x75/0x120 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: 0023:0xf7353579
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:00000000f5f455ac EFLAGS: 00000292 ORIG_RAX: 00000000000000bb
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000000004
RDX: 0000000020002080 RSI: 000000000000023b RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
syz-executor.3 (11149): drop_caches: 2
syz-executor.3 (11149): drop_caches: 2
----------------
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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