[syzbot] [ext4?] possible deadlock in ext4_xattr_set_handle (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: edc00350d205 Merge tag 'block-6.2-2023-01-20' of git://git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=134b1441480000
kernel config: https://syzkaller.appspot.com/x/.config?x=899d86a7610a0ea0
dashboard link: https://syzkaller.appspot.com/bug?extid=edce54daffee36421b4c
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: i386

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+edce54...@syzkaller.appspotmail.com

ext4 filesystem being mounted at /syzkaller-testdir3627507797/syzkaller.9jT2hR/316/file0 supports timestamps until 2038 (0x7fffffff)
======================================================
WARNING: possible circular locking dependency detected
6.2.0-rc4-syzkaller-00350-gedc00350d205 #0 Not tainted
------------------------------------------------------
syz-executor.2/573 is trying to acquire lock:
ffffffff8c8d4f60 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:271 [inline]
ffffffff8c8d4f60 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slab.h:720 [inline]
ffffffff8c8d4f60 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:3434 [inline]
ffffffff8c8d4f60 (fs_reclaim){+.+.}-{0:0}, at: __kmem_cache_alloc_node+0x41/0x430 mm/slub.c:3491

but task is already holding lock:
ffff8880277eb2f0 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
ffff8880277eb2f0 (&ei->xattr_sem){++++}-{3:3}, at: ext4_xattr_set_handle+0x160/0x1510 fs/ext4/xattr.c:2305

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&ei->xattr_sem){++++}-{3:3}:
down_write+0x94/0x220 kernel/locking/rwsem.c:1562
ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
ext4_xattr_set_handle+0x160/0x1510 fs/ext4/xattr.c:2305
__ext4_set_acl+0x35c/0x5a0 fs/ext4/acl.c:217
ext4_set_acl+0x484/0x5f0 fs/ext4/acl.c:259
set_posix_acl+0x25b/0x320 fs/posix_acl.c:957
vfs_remove_acl+0x276/0x640 fs/posix_acl.c:1209
ovl_do_remove_acl fs/overlayfs/overlayfs.h:292 [inline]
ovl_workdir_create+0x462/0x800 fs/overlayfs/super.c:821
ovl_make_workdir fs/overlayfs/super.c:1294 [inline]
ovl_get_workdir fs/overlayfs/super.c:1444 [inline]
ovl_fill_super+0x1a02/0x6330 fs/overlayfs/super.c:2000
mount_nodev+0x64/0x120 fs/super.c:1405
legacy_get_tree+0x109/0x220 fs/fs_context.c:610
vfs_get_tree+0x8d/0x2f0 fs/super.c:1489
do_new_mount fs/namespace.c:3145 [inline]
path_mount+0x132a/0x1e20 fs/namespace.c:3475
do_mount fs/namespace.c:3488 [inline]
__do_sys_mount fs/namespace.c:3697 [inline]
__se_sys_mount fs/namespace.c:3674 [inline]
__ia32_sys_mount+0x282/0x300 fs/namespace.c:3674
do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
__do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
entry_SYSENTER_compat_after_hwframe+0x70/0x82

-> #1 (jbd2_handle){++++}-{0:0}:
start_this_handle+0xfe7/0x14a0 fs/jbd2/transaction.c:463
jbd2__journal_start+0x39d/0x9b0 fs/jbd2/transaction.c:520
__ext4_journal_start_sb+0x6e9/0x860 fs/ext4/ext4_jbd2.c:111
__ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
ext4_dirty_inode+0xa5/0x130 fs/ext4/inode.c:6107
__mark_inode_dirty+0x247/0x11e0 fs/fs-writeback.c:2419
mark_inode_dirty_sync include/linux/fs.h:2470 [inline]
iput.part.0+0x57/0x880 fs/inode.c:1770
iput+0x5c/0x80 fs/inode.c:1763
dentry_unlink_inode+0x2b1/0x460 fs/dcache.c:401
__dentry_kill+0x3c0/0x640 fs/dcache.c:607
shrink_dentry_list+0x240/0x800 fs/dcache.c:1201
prune_dcache_sb+0xeb/0x150 fs/dcache.c:1282
super_cache_scan+0x33a/0x590 fs/super.c:104
do_shrink_slab+0x464/0xce0 mm/vmscan.c:843
shrink_slab+0x175/0x660 mm/vmscan.c:1003
shrink_node_memcgs mm/vmscan.c:6140 [inline]
shrink_node+0x95d/0x1f40 mm/vmscan.c:6169
kswapd_shrink_node mm/vmscan.c:6960 [inline]
balance_pgdat+0x8f5/0x1530 mm/vmscan.c:7150
kswapd+0x70b/0xfc0 mm/vmscan.c:7410
kthread+0x2e8/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

-> #0 (fs_reclaim){+.+.}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain kernel/locking/lockdep.c:3831 [inline]
__lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
lock_acquire kernel/locking/lockdep.c:5668 [inline]
lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
__fs_reclaim_acquire mm/page_alloc.c:4674 [inline]
fs_reclaim_acquire+0x11d/0x160 mm/page_alloc.c:4688
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook mm/slab.h:720 [inline]
slab_alloc_node mm/slub.c:3434 [inline]
__kmem_cache_alloc_node+0x41/0x430 mm/slub.c:3491
__do_kmalloc_node mm/slab_common.c:967 [inline]
__kmalloc_node+0x4d/0xd0 mm/slab_common.c:975
kmalloc_node include/linux/slab.h:610 [inline]
kvmalloc_node+0x76/0x1a0 mm/util.c:581
kvmalloc include/linux/slab.h:737 [inline]
ext4_xattr_inode_cache_find fs/ext4/xattr.c:1484 [inline]
ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1527 [inline]
ext4_xattr_set_entry+0x1d92/0x3a00 fs/ext4/xattr.c:1669
ext4_xattr_block_set+0x61b/0x3000 fs/ext4/xattr.c:1906
ext4_xattr_set_handle+0xd8a/0x1510 fs/ext4/xattr.c:2390
ext4_xattr_set+0x144/0x360 fs/ext4/xattr.c:2492
__vfs_setxattr+0x173/0x1e0 fs/xattr.c:202
__vfs_setxattr_noperm+0x129/0x5f0 fs/xattr.c:236
__vfs_setxattr_locked+0x1d3/0x260 fs/xattr.c:297
vfs_setxattr+0x143/0x340 fs/xattr.c:323
do_setxattr+0x151/0x190 fs/xattr.c:608
setxattr+0x146/0x160 fs/xattr.c:631
path_setxattr+0x197/0x1c0 fs/xattr.c:650
__do_sys_setxattr fs/xattr.c:666 [inline]
__se_sys_setxattr fs/xattr.c:662 [inline]
__ia32_sys_setxattr+0xc0/0x160 fs/xattr.c:662
do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
__do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
entry_SYSENTER_compat_after_hwframe+0x70/0x82

other info that might help us debug this:

Chain exists of:
fs_reclaim --> jbd2_handle --> &ei->xattr_sem

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&ei->xattr_sem);
lock(jbd2_handle);
lock(&ei->xattr_sem);
lock(fs_reclaim);

*** DEADLOCK ***

3 locks held by syz-executor.2/573:
#0: ffff8880650a0460 (sb_writers#4){.+.+}-{0:0}, at: path_setxattr+0xb2/0x1c0 fs/xattr.c:648
#1: ffff8880277eb628 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
#1: ffff8880277eb628 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: vfs_setxattr+0x120/0x340 fs/xattr.c:322
#2: ffff8880277eb2f0 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
#2: ffff8880277eb2f0 (&ei->xattr_sem){++++}-{3:3}, at: ext4_xattr_set_handle+0x160/0x1510 fs/ext4/xattr.c:2305

stack backtrace:
CPU: 2 PID: 573 Comm: syz-executor.2 Not tainted 6.2.0-rc4-syzkaller-00350-gedc00350d205 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2177
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain kernel/locking/lockdep.c:3831 [inline]
__lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
lock_acquire kernel/locking/lockdep.c:5668 [inline]
lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
__fs_reclaim_acquire mm/page_alloc.c:4674 [inline]
fs_reclaim_acquire+0x11d/0x160 mm/page_alloc.c:4688
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook mm/slab.h:720 [inline]
slab_alloc_node mm/slub.c:3434 [inline]
__kmem_cache_alloc_node+0x41/0x430 mm/slub.c:3491
__do_kmalloc_node mm/slab_common.c:967 [inline]
__kmalloc_node+0x4d/0xd0 mm/slab_common.c:975
kmalloc_node include/linux/slab.h:610 [inline]
kvmalloc_node+0x76/0x1a0 mm/util.c:581
kvmalloc include/linux/slab.h:737 [inline]
ext4_xattr_inode_cache_find fs/ext4/xattr.c:1484 [inline]
ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1527 [inline]
ext4_xattr_set_entry+0x1d92/0x3a00 fs/ext4/xattr.c:1669
ext4_xattr_block_set+0x61b/0x3000 fs/ext4/xattr.c:1906
ext4_xattr_set_handle+0xd8a/0x1510 fs/ext4/xattr.c:2390
ext4_xattr_set+0x144/0x360 fs/ext4/xattr.c:2492
__vfs_setxattr+0x173/0x1e0 fs/xattr.c:202
__vfs_setxattr_noperm+0x129/0x5f0 fs/xattr.c:236
__vfs_setxattr_locked+0x1d3/0x260 fs/xattr.c:297
vfs_setxattr+0x143/0x340 fs/xattr.c:323
do_setxattr+0x151/0x190 fs/xattr.c:608
setxattr+0x146/0x160 fs/xattr.c:631
path_setxattr+0x197/0x1c0 fs/xattr.c:650
__do_sys_setxattr fs/xattr.c:666 [inline]
__se_sys_setxattr fs/xattr.c:662 [inline]
__ia32_sys_setxattr+0xc0/0x160 fs/xattr.c:662
do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
__do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
entry_SYSENTER_compat_after_hwframe+0x70/0x82
RIP: 0023:0xf7f96549
Code: 03 74 c0 01 10 05 03 74 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 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:00000000f7f915cc EFLAGS: 00000296 ORIG_RAX: 00000000000000e2
RAX: ffffffffffffffda RBX: 00000000200000c0 RCX: 0000000020000180
RDX: 00000000200005c0 RSI: 0000000000002000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
----------------
Code disassembly (best guess):
0: 03 74 c0 01 add 0x1(%rax,%rax,8),%esi
4: 10 05 03 74 b8 01 adc %al,0x1b87403(%rip) # 0x1b8740d
a: 10 06 adc %al,(%rsi)
c: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi
10: 10 07 adc %al,(%rdi)
12: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi
16: 10 08 adc %cl,(%rax)
18: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi
1c: 00 00 add %al,(%rax)
1e: 00 00 add %al,(%rax)
20: 00 51 52 add %dl,0x52(%rcx)
23: 55 push %rbp
24: 89 e5 mov %esp,%ebp
26: 0f 34 sysenter
28: cd 80 int $0x80
* 2a: 5d pop %rbp <-- trapping instruction
2b: 5a pop %rdx
2c: 59 pop %rcx
2d: c3 retq
2e: 90 nop
2f: 90 nop
30: 90 nop
31: 90 nop
32: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi
39: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi


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[Jan Kara]

Hi!

So I don't see how the below is ever possible:

> -> #0 (fs_reclaim){+.+.}-{0:0}:
> check_prev_add kernel/locking/lockdep.c:3097 [inline]
> check_prevs_add kernel/locking/lockdep.c:3216 [inline]
> validate_chain kernel/locking/lockdep.c:3831 [inline]
> __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
> lock_acquire kernel/locking/lockdep.c:5668 [inline]
> lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
> __fs_reclaim_acquire mm/page_alloc.c:4674 [inline]

So we are acquiring fs_reclaim here which means that
current_gfp_context(gfp_mask) contained __GFP_FS...

> fs_reclaim_acquire+0x11d/0x160 mm/page_alloc.c:4688
> might_alloc include/linux/sched/mm.h:271 [inline]
> slab_pre_alloc_hook mm/slab.h:720 [inline]
> slab_alloc_node mm/slub.c:3434 [inline]
> __kmem_cache_alloc_node+0x41/0x430 mm/slub.c:3491
> __do_kmalloc_node mm/slab_common.c:967 [inline]
> __kmalloc_node+0x4d/0xd0 mm/slab_common.c:975
> kmalloc_node include/linux/slab.h:610 [inline]
> kvmalloc_node+0x76/0x1a0 mm/util.c:581
> kvmalloc include/linux/slab.h:737 [inline]
> ext4_xattr_inode_cache_find fs/ext4/xattr.c:1484 [inline]
> ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1527 [inline]
> ext4_xattr_set_entry+0x1d92/0x3a00 fs/ext4/xattr.c:1669
> ext4_xattr_block_set+0x61b/0x3000 fs/ext4/xattr.c:1906
> ext4_xattr_set_handle+0xd8a/0x1510 fs/ext4/xattr.c:2390
> ext4_xattr_set+0x144/0x360 fs/ext4/xattr.c:2492

... however here we've started a transaction so we should have
PF_MEMALLOC_NOFS set?

The only good explanation I have is that lockdep is mixing dependencies
from an ext4 filesystem without a journal with dependencies created by
filesystem with a journal. Since we have no reproducer, it's hard to
tell.

> __vfs_setxattr+0x173/0x1e0 fs/xattr.c:202
> __vfs_setxattr_noperm+0x129/0x5f0 fs/xattr.c:236
> __vfs_setxattr_locked+0x1d3/0x260 fs/xattr.c:297
> vfs_setxattr+0x143/0x340 fs/xattr.c:323
> do_setxattr+0x151/0x190 fs/xattr.c:608
> setxattr+0x146/0x160 fs/xattr.c:631
> path_setxattr+0x197/0x1c0 fs/xattr.c:650
> __do_sys_setxattr fs/xattr.c:666 [inline]
> __se_sys_setxattr fs/xattr.c:662 [inline]
> __ia32_sys_setxattr+0xc0/0x160 fs/xattr.c:662
> do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
> __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
> do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
> entry_SYSENTER_compat_after_hwframe+0x70/0x82

Honza
--
Jan Kara <ja...@suse.com>
SUSE Labs, CR

[Dmitry Vyukov]

Should the xattr_sem class be differentiated based on use/no-use of the journal?

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 14f8db1c0f9a Merge branch 'for-next/core' into for-kernelci
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=1663f338280000
kernel config: https://syzkaller.appspot.com/x/.config?x=a837a8ba7e88bb45
dashboard link: https://syzkaller.appspot.com/bug?extid=edce54daffee36421b4c
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17595ed4280000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16e85322280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ad6ce516eed3/disk-14f8db1c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1f38c2cc7667/vmlinux-14f8db1c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d795115eee39/Image-14f8db1c.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/092c100a5922/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+edce54...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 512
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 without journal. Quota mode: writeback.

======================================================
WARNING: possible circular locking dependency detected

6.3.0-rc7-syzkaller-g14f8db1c0f9a #0 Not tainted
------------------------------------------------------
syz-executor392/5925 is trying to acquire lock:
ffff0000e0dbb2f0 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
ffff0000e0dbb2f0 (&ei->xattr_sem){++++}-{3:3}, at: ext4_xattr_set_handle+0x1e0/0x12d8 fs/ext4/xattr.c:2373

but task is already holding lock:

ffff0000e0dbb628 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
ffff0000e0dbb628 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}, at: vfs_setxattr+0x17c/0x344 fs/xattr.c:323

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}:
down_write+0x50/0xc0 kernel/locking/rwsem.c:1573
inode_lock include/linux/fs.h:758 [inline]
ext4_xattr_inode_create fs/ext4/xattr.c:1525 [inline]
ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1608 [inline]
ext4_xattr_set_entry+0x2394/0x2c3c fs/ext4/xattr.c:1737
ext4_xattr_block_set+0x8e0/0x2cc4 fs/ext4/xattr.c:2043
ext4_xattr_set_handle+0xb2c/0x12d8 fs/ext4/xattr.c:2458
ext4_xattr_set+0x1e0/0x354 fs/ext4/xattr.c:2560
ext4_xattr_trusted_set+0x4c/0x64 fs/ext4/xattr_trusted.c:38
__vfs_setxattr+0x3d8/0x400 fs/xattr.c:203
__vfs_setxattr_noperm+0x110/0x528 fs/xattr.c:237
__vfs_setxattr_locked+0x1ec/0x218 fs/xattr.c:298
vfs_setxattr+0x1a8/0x344 fs/xattr.c:324
do_setxattr fs/xattr.c:609 [inline]
setxattr+0x208/0x29c fs/xattr.c:632
path_setxattr+0x17c/0x258 fs/xattr.c:651
__do_sys_setxattr fs/xattr.c:667 [inline]
__se_sys_setxattr fs/xattr.c:663 [inline]
__arm64_sys_setxattr+0xbc/0xd8 fs/xattr.c:663
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193
el0_svc+0x4c/0x15c arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591

-> #0 (&ei->xattr_sem){++++}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain kernel/locking/lockdep.c:3832 [inline]
__lock_acquire+0x3338/0x764c kernel/locking/lockdep.c:5056
lock_acquire+0x238/0x718 kernel/locking/lockdep.c:5669
down_write+0x50/0xc0 kernel/locking/rwsem.c:1573
ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
ext4_xattr_set_handle+0x1e0/0x12d8 fs/ext4/xattr.c:2373
ext4_xattr_set+0x1e0/0x354 fs/ext4/xattr.c:2560
ext4_xattr_trusted_set+0x4c/0x64 fs/ext4/xattr_trusted.c:38
__vfs_setxattr+0x3d8/0x400 fs/xattr.c:203
__vfs_setxattr_noperm+0x110/0x528 fs/xattr.c:237
__vfs_setxattr_locked+0x1ec/0x218 fs/xattr.c:298
vfs_setxattr+0x1a8/0x344 fs/xattr.c:324
do_setxattr fs/xattr.c:609 [inline]
setxattr+0x208/0x29c fs/xattr.c:632
path_setxattr+0x17c/0x258 fs/xattr.c:651
__do_sys_setxattr fs/xattr.c:667 [inline]
__se_sys_setxattr fs/xattr.c:663 [inline]
__arm64_sys_setxattr+0xbc/0xd8 fs/xattr.c:663
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193
el0_svc+0x4c/0x15c arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----

lock(&ea_inode->i_rwsem#8/1);
lock(&ei->xattr_sem);
lock(&ea_inode->i_rwsem#8/1);
lock(&ei->xattr_sem);

*** DEADLOCK ***

2 locks held by syz-executor392/5925:
#0: ffff0000d80e6460 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:394
#1: ffff0000e0dbb628 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
#1: ffff0000e0dbb628 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}, at: vfs_setxattr+0x17c/0x344 fs/xattr.c:323

stack backtrace:
CPU: 1 PID: 5925 Comm: syz-executor392 Not tainted 6.3.0-rc7-syzkaller-g14f8db1c0f9a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
Call trace:
dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:233
show_stack+0x2c/0x44 arch/arm64/kernel/stacktrace.c:240
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106
dump_stack+0x1c/0x28 lib/dump_stack.c:113
print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2056
check_noncircular+0x2cc/0x378 kernel/locking/lockdep.c:2178
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain kernel/locking/lockdep.c:3832 [inline]
__lock_acquire+0x3338/0x764c kernel/locking/lockdep.c:5056
lock_acquire+0x238/0x718 kernel/locking/lockdep.c:5669
down_write+0x50/0xc0 kernel/locking/rwsem.c:1573
ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
ext4_xattr_set_handle+0x1e0/0x12d8 fs/ext4/xattr.c:2373
ext4_xattr_set+0x1e0/0x354 fs/ext4/xattr.c:2560
ext4_xattr_trusted_set+0x4c/0x64 fs/ext4/xattr_trusted.c:38
__vfs_setxattr+0x3d8/0x400 fs/xattr.c:203
__vfs_setxattr_noperm+0x110/0x528 fs/xattr.c:237
__vfs_setxattr_locked+0x1ec/0x218 fs/xattr.c:298
vfs_setxattr+0x1a8/0x344 fs/xattr.c:324
do_setxattr fs/xattr.c:609 [inline]
setxattr+0x208/0x29c fs/xattr.c:632
path_setxattr+0x17c/0x258 fs/xattr.c:651
__do_sys_setxattr fs/xattr.c:667 [inline]
__se_sys_setxattr fs/xattr.c:663 [inline]
__arm64_sys_setxattr+0xbc/0xd8 fs/xattr.c:663
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193
el0_svc+0x4c/0x15c arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591


---
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