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Subjectpossible deadlock in evict
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Hello,

syzbot found the following issue on:

HEAD commit: c6d8570e Merge tag 'io_uring-5.11-2021-02-12' of git://git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=123a4be2d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=bec717fd4ac4bf03
dashboard link: https://syzkaller.appspot.com/bug?extid=1b2c6989ec12e467d65c

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1b2c6989ec12e467d65c@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
5.11.0-rc7-syzkaller #0 Not tainted
------------------------------------------------------
kswapd0/2232 is trying to acquire lock:
ffff88801f552650 (sb_internal){.+.+}-{0:0}, at: evict+0x2ed/0x6b0 fs/inode.c:577

but task is already holding lock:
ffffffff8be89240 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x0/0x30 mm/page_alloc.c:5195

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (fs_reclaim){+.+.}-{0:0}:
__fs_reclaim_acquire mm/page_alloc.c:4326 [inline]
fs_reclaim_acquire+0x117/0x150 mm/page_alloc.c:4340
might_alloc include/linux/sched/mm.h:193 [inline]
slab_pre_alloc_hook mm/slab.h:493 [inline]
slab_alloc_node mm/slab.c:3221 [inline]
kmem_cache_alloc_node_trace+0x48/0x520 mm/slab.c:3596
__do_kmalloc_node mm/slab.c:3618 [inline]
__kmalloc_node+0x38/0x60 mm/slab.c:3626
kmalloc_node include/linux/slab.h:575 [inline]
kvmalloc_node+0x61/0xf0 mm/util.c:587
kvmalloc include/linux/mm.h:781 [inline]
ext4_xattr_inode_cache_find fs/ext4/xattr.c:1465 [inline]
ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1508 [inline]
ext4_xattr_set_entry+0x1ce6/0x3780 fs/ext4/xattr.c:1649
ext4_xattr_ibody_set+0x78/0x2b0 fs/ext4/xattr.c:2224
ext4_xattr_set_handle+0x8f4/0x13e0 fs/ext4/xattr.c:2380
ext4_xattr_set+0x13a/0x340 fs/ext4/xattr.c:2493
__vfs_setxattr+0x10e/0x170 fs/xattr.c:177
__vfs_setxattr_noperm+0x11a/0x4c0 fs/xattr.c:208
__vfs_setxattr_locked+0x1bf/0x250 fs/xattr.c:266
vfs_setxattr+0x135/0x320 fs/xattr.c:291
setxattr+0x1ff/0x290 fs/xattr.c:553
path_setxattr+0x170/0x190 fs/xattr.c:572
__do_sys_setxattr fs/xattr.c:587 [inline]
__se_sys_setxattr fs/xattr.c:583 [inline]
__x64_sys_setxattr+0xc0/0x160 fs/xattr.c:583
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

-> #2 (&ei->xattr_sem){++++}-{3:3}:
down_write+0x8d/0x150 kernel/locking/rwsem.c:1406
ext4_write_lock_xattr fs/ext4/xattr.h:142 [inline]
ext4_xattr_set_handle+0x15c/0x13e0 fs/ext4/xattr.c:2308
ext4_initxattrs+0xb5/0x120 fs/ext4/xattr_security.c:43
security_inode_init_security+0x1c4/0x370 security/security.c:1054
__ext4_new_inode+0x3963/0x5570 fs/ext4/ialloc.c:1317
ext4_create+0x2c3/0x4c0 fs/ext4/namei.c:2613
lookup_open.isra.0+0xf85/0x1350 fs/namei.c:3106
open_last_lookups fs/namei.c:3180 [inline]
path_openat+0x96d/0x2730 fs/namei.c:3368
do_filp_open+0x17e/0x3c0 fs/namei.c:3398
do_sys_openat2+0x16d/0x420 fs/open.c:1172
do_sys_open fs/open.c:1188 [inline]
__do_sys_open fs/open.c:1196 [inline]
__se_sys_open fs/open.c:1192 [inline]
__x64_sys_open+0x119/0x1c0 fs/open.c:1192
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

-> #1 (jbd2_handle){++++}-{0:0}:
start_this_handle+0xfb4/0x1380 fs/jbd2/transaction.c:446
jbd2__journal_start+0x399/0x930 fs/jbd2/transaction.c:503
__ext4_journal_start_sb+0x227/0x4a0 fs/ext4/ext4_jbd2.c:105
ext4_sample_last_mounted fs/ext4/file.c:804 [inline]
ext4_file_open+0x613/0xb40 fs/ext4/file.c:832
do_dentry_open+0x4b9/0x11b0 fs/open.c:817
do_open fs/namei.c:3254 [inline]
path_openat+0x1b9a/0x2730 fs/namei.c:3371
do_filp_open+0x17e/0x3c0 fs/namei.c:3398
do_sys_openat2+0x16d/0x420 fs/open.c:1172
do_sys_open fs/open.c:1188 [inline]
__do_sys_open fs/open.c:1196 [inline]
__se_sys_open fs/open.c:1192 [inline]
__x64_sys_open+0x119/0x1c0 fs/open.c:1192
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

-> #0 (sb_internal){.+.+}-{0:0}:
check_prev_add kernel/locking/lockdep.c:2868 [inline]
check_prevs_add kernel/locking/lockdep.c:2993 [inline]
validate_chain kernel/locking/lockdep.c:3608 [inline]
__lock_acquire+0x2b26/0x54f0 kernel/locking/lockdep.c:4832
lock_acquire kernel/locking/lockdep.c:5442 [inline]
lock_acquire+0x1a8/0x720 kernel/locking/lockdep.c:5407
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1592 [inline]
sb_start_intwrite include/linux/fs.h:1709 [inline]
ext4_evict_inode+0xe6f/0x1940 fs/ext4/inode.c:241
evict+0x2ed/0x6b0 fs/inode.c:577
iput_final fs/inode.c:1653 [inline]
iput.part.0+0x57e/0x810 fs/inode.c:1679
iput fs/inode.c:1669 [inline]
inode_lru_isolate+0x301/0x4f0 fs/inode.c:778
__list_lru_walk_one+0x178/0x5c0 mm/list_lru.c:222
list_lru_walk_one+0x99/0xd0 mm/list_lru.c:266
list_lru_shrink_walk include/linux/list_lru.h:195 [inline]
prune_icache_sb+0xdc/0x140 fs/inode.c:803
super_cache_scan+0x38d/0x590 fs/super.c:107
do_shrink_slab+0x3e4/0x9f0 mm/vmscan.c:511
shrink_slab+0x16f/0x5d0 mm/vmscan.c:672
shrink_node_memcgs mm/vmscan.c:2665 [inline]
shrink_node+0x8cc/0x1de0 mm/vmscan.c:2780
kswapd_shrink_node mm/vmscan.c:3523 [inline]
balance_pgdat+0x745/0x1270 mm/vmscan.c:3681
kswapd+0x5b1/0xdb0 mm/vmscan.c:3938
kthread+0x3b1/0x4a0 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

other info that might help us debug this:

Chain exists of:
sb_internal --> &ei->xattr_sem --> fs_reclaim

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(fs_reclaim);
lock(&ei->xattr_sem);
lock(fs_reclaim);
lock(sb_internal);

*** DEADLOCK ***

3 locks held by kswapd0/2232:
#0: ffffffff8be89240 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x0/0x30 mm/page_alloc.c:5195
#1: ffffffff8be50770 (shrinker_rwsem){++++}-{3:3}, at: shrink_slab+0xc7/0x5d0 mm/vmscan.c:662
#2: ffff88801f5520e0 (&type->s_umount_key#49){++++}-{3:3}, at: trylock_super fs/super.c:418 [inline]
#2: ffff88801f5520e0 (&type->s_umount_key#49){++++}-{3:3}, at: super_cache_scan+0x6c/0x590 fs/super.c:80

stack backtrace:
CPU: 3 PID: 2232 Comm: kswapd0 Not tainted 5.11.0-rc7-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x107/0x163 lib/dump_stack.c:120
check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2117
check_prev_add kernel/locking/lockdep.c:2868 [inline]
check_prevs_add kernel/locking/lockdep.c:2993 [inline]
validate_chain kernel/locking/lockdep.c:3608 [inline]
__lock_acquire+0x2b26/0x54f0 kernel/locking/lockdep.c:4832
lock_acquire kernel/locking/lockdep.c:5442 [inline]
lock_acquire+0x1a8/0x720 kernel/locking/lockdep.c:5407
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1592 [inline]
sb_start_intwrite include/linux/fs.h:1709 [inline]
ext4_evict_inode+0xe6f/0x1940 fs/ext4/inode.c:241
evict+0x2ed/0x6b0 fs/inode.c:577
iput_final fs/inode.c:1653 [inline]
iput.part.0+0x57e/0x810 fs/inode.c:1679
iput fs/inode.c:1669 [inline]
inode_lru_isolate+0x301/0x4f0 fs/inode.c:778
__list_lru_walk_one+0x178/0x5c0 mm/list_lru.c:222
list_lru_walk_one+0x99/0xd0 mm/list_lru.c:266
list_lru_shrink_walk include/linux/list_lru.h:195 [inline]
prune_icache_sb+0xdc/0x140 fs/inode.c:803
super_cache_scan+0x38d/0x590 fs/super.c:107
do_shrink_slab+0x3e4/0x9f0 mm/vmscan.c:511
shrink_slab+0x16f/0x5d0 mm/vmscan.c:672
shrink_node_memcgs mm/vmscan.c:2665 [inline]
shrink_node+0x8cc/0x1de0 mm/vmscan.c:2780
kswapd_shrink_node mm/vmscan.c:3523 [inline]
balance_pgdat+0x745/0x1270 mm/vmscan.c:3681
kswapd+0x5b1/0xdb0 mm/vmscan.c:3938
kthread+0x3b1/0x4a0 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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