[syzbot] [xfs?] possible deadlock in xfs_qm_dqpurge

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9d1ddab261f3 Merge tag '6.9-rc5-smb-client-fixes' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=131236e3180000
kernel config: https://syzkaller.appspot.com/x/.config?x=19891bd776e81b8b
dashboard link: https://syzkaller.appspot.com/bug?extid=a191ccc95425c3409faa
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-9d1ddab2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ee7f420f8fb9/vmlinux-9d1ddab2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/18bef520c373/bzImage-9d1ddab2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a191cc...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.9.0-rc5-syzkaller-00036-g9d1ddab261f3 #0 Not tainted
------------------------------------------------------
syz-executor.2/5415 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: kmalloc_trace+0x51/0x330 mm/slub.c:3992

but task is already holding lock:
ffff8880767b0868 (&xfs_dquot_group_class){+.+.}-{3:3}, at: xfs_dqlock fs/xfs/xfs_dquot.h:125 [inline]
ffff8880767b0868 (&xfs_dquot_group_class){+.+.}-{3:3}, at: xfs_qm_dqpurge+0xc5/0x630 fs/xfs/xfs_qm.c:129

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&xfs_dquot_group_class){+.+.}-{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+0x1c6/0x2d0 fs/xfs/xfs_qm.c:337
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
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_open fs/open.c:1472 [inline]
__se_compat_sys_open fs/open.c:1470 [inline]
__ia32_compat_sys_open+0x147/0x1e0 fs/open.c:1470
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:3746 [inline]
slab_alloc_node mm/slub.c:3827 [inline]
kmalloc_trace+0x51/0x330 mm/slub.c:3992
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_dqpurge+0x1d3/0x630 fs/xfs/xfs_qm.c:149
xfs_qm_dquot_walk.isra.0+0x217/0x3d0 fs/xfs/xfs_qm.c:88
xfs_qm_dqpurge_all fs/xfs/xfs_qm.c:194 [inline]
xfs_qm_unmount+0x92/0x1c0 fs/xfs/xfs_qm.c:206
xfs_unmountfs+0x76/0x240 fs/xfs/xfs_mount.c:1076
xfs_fs_put_super+0x61/0x160 fs/xfs/xfs_super.c:1134
generic_shutdown_super+0x159/0x3d0 fs/super.c:641
kill_block_super+0x3b/0x90 fs/super.c:1675
xfs_kill_sb+0x15/0x50 fs/xfs/xfs_super.c:2026
deactivate_locked_super+0xbe/0x1a0 fs/super.c:472
deactivate_super+0xde/0x100 fs/super.c:505
cleanup_mnt+0x222/0x450 fs/namespace.c:1267
task_work_run+0x14e/0x250 kernel/task_work.c:180
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x278/0x2a0 kernel/entry/common.c:218
__do_fast_syscall_32+0x82/0x120 arch/x86/entry/common.c:389
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 --> &xfs_dquot_group_class

Possible unsafe locking scenario:

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

*** DEADLOCK ***

3 locks held by syz-executor.2/5415:
#0: ffff8880267b00e0 (&type->s_umount_key#52){++++}-{3:3}, at: __super_lock fs/super.c:56 [inline]
#0: ffff8880267b00e0 (&type->s_umount_key#52){++++}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
#0: ffff8880267b00e0 (&type->s_umount_key#52){++++}-{3:3}, at: deactivate_super+0xd6/0x100 fs/super.c:504
#1: ffff88805a740158 (&qinf->qi_tree_lock){+.+.}-{3:3}, at: xfs_qm_dquot_walk.isra.0+0x111/0x3d0 fs/xfs/xfs_qm.c:75
#2: ffff8880767b0868 (&xfs_dquot_group_class){+.+.}-{3:3}, at: xfs_dqlock fs/xfs/xfs_dquot.h:125 [inline]
#2: ffff8880767b0868 (&xfs_dquot_group_class){+.+.}-{3:3}, at: xfs_qm_dqpurge+0xc5/0x630 fs/xfs/xfs_qm.c:129

stack backtrace:
CPU: 3 PID: 5415 Comm: syz-executor.2 Not tainted 6.9.0-rc5-syzkaller-00036-g9d1ddab261f3 #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]
kmalloc_trace+0x51/0x330 mm/slub.c:3992
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_dqpurge+0x1d3/0x630 fs/xfs/xfs_qm.c:149
xfs_qm_dquot_walk.isra.0+0x217/0x3d0 fs/xfs/xfs_qm.c:88
xfs_qm_dqpurge_all fs/xfs/xfs_qm.c:194 [inline]
xfs_qm_unmount+0x92/0x1c0 fs/xfs/xfs_qm.c:206
xfs_unmountfs+0x76/0x240 fs/xfs/xfs_mount.c:1076
xfs_fs_put_super+0x61/0x160 fs/xfs/xfs_super.c:1134
generic_shutdown_super+0x159/0x3d0 fs/super.c:641
kill_block_super+0x3b/0x90 fs/super.c:1675
xfs_kill_sb+0x15/0x50 fs/xfs/xfs_super.c:2026
deactivate_locked_super+0xbe/0x1a0 fs/super.c:472
deactivate_super+0xde/0x100 fs/super.c:505
cleanup_mnt+0x222/0x450 fs/namespace.c:1267
task_work_run+0x14e/0x250 kernel/task_work.c:180
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x278/0x2a0 kernel/entry/common.c:218
__do_fast_syscall_32+0x82/0x120 arch/x86/entry/common.c:389
do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf7334579
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:00000000ffb89538 EFLAGS: 00000292 ORIG_RAX: 0000000000000034
RAX: 0000000000000000 RBX: 00000000ffb8a680 RCX: 0000000000000009
RDX: 00000000f748bff4 RSI: 0000000000000064 RDI: 00000000ffb8a680
RBP: 00000000f73db3bd R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
EXT4-fs (loop2): unmounting filesystem 76b65be2-f6da-4727-8c75-0525a5b65a09.
XFS (loop2): Unmounting Filesystem a2f82aab-77f8-4286-afd4-a8f747a74bab
XFS (loop2): Unmounting Filesystem a2f82aab-77f8-4286-afd4-a8f747a74bab
----------------
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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[Dave Chinner]

On Sun, Apr 28, 2024 at 12:19:19AM -0700, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 9d1ddab261f3 Merge tag '6.9-rc5-smb-client-fixes' of git:/..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=131236e3180000
> kernel config: https://syzkaller.appspot.com/x/.config?x=19891bd776e81b8b
> dashboard link: https://syzkaller.appspot.com/bug?extid=a191ccc95425c3409faa
> compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> userspace arch: i386

#syz dup: possible deadlock in xfs_ilock_data_map_shared

--
Dave Chinner
da...@fromorbit.com