[syzbot] [ext4?] possible deadlock in ext4_xattr_set_handle (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e789286468a9 Merge tag 'x86-urgent-2023-09-17' of git://gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12f3cef8680000
kernel config: https://syzkaller.appspot.com/x/.config?x=dea9a2f141d69d34
dashboard link: https://syzkaller.appspot.com/bug?extid=ea0ba556b26f54698271
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-e7892864.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1429a45d2526/vmlinux-e7892864.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7b5ffe979a44/bzImage-e7892864.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ea0ba5...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.6.0-rc1-syzkaller-00269-ge789286468a9 #0 Not tainted
------------------------------------------------------
syz-executor.2/16393 is trying to acquire lock:
ffff88801c2532c8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
ffff88801c2532c8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_xattr_set_handle+0x159/0x1420 fs/ext4/xattr.c:2371

but task is already holding lock:
ffff8880444e0988 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x10d6/0x15e0 fs/jbd2/transaction.c:463

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (jbd2_handle){++++}-{0:0}:
start_this_handle+0x10fc/0x15e0 fs/jbd2/transaction.c:463
jbd2__journal_start+0x391/0x690 fs/jbd2/transaction.c:520
__ext4_journal_start_sb+0x40f/0x5c0 fs/ext4/ext4_jbd2.c:112
__ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
ext4_dirty_inode+0xa1/0x130 fs/ext4/inode.c:5953
__mark_inode_dirty+0x1e0/0xd50 fs/fs-writeback.c:2430
mark_inode_dirty_sync include/linux/fs.h:2271 [inline]
iput.part.0+0x5b/0x7a0 fs/inode.c:1798
iput+0x5c/0x80 fs/inode.c:1791
dentry_unlink_inode+0x292/0x430 fs/dcache.c:401
__dentry_kill+0x3b8/0x640 fs/dcache.c:607
shrink_dentry_list+0x22b/0x7d0 fs/dcache.c:1201
prune_dcache_sb+0xeb/0x150 fs/dcache.c:1282
super_cache_scan+0x31f/0x540 fs/super.c:228
do_shrink_slab+0x422/0xaa0 mm/vmscan.c:900
shrink_slab+0x17f/0x6e0 mm/vmscan.c:1060
shrink_one+0x4f7/0x700 mm/vmscan.c:5417
shrink_many mm/vmscan.c:5469 [inline]
lru_gen_shrink_node mm/vmscan.c:5586 [inline]
shrink_node+0x20d4/0x37a0 mm/vmscan.c:6526
kswapd_shrink_node mm/vmscan.c:7331 [inline]
balance_pgdat+0xa32/0x1b80 mm/vmscan.c:7521
kswapd+0x5be/0xbf0 mm/vmscan.c:7781
kthread+0x33c/0x440 kernel/kthread.c:388
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

-> #1 (fs_reclaim){+.+.}-{0:0}:
__fs_reclaim_acquire mm/page_alloc.c:3551 [inline]
fs_reclaim_acquire+0x100/0x150 mm/page_alloc.c:3565
might_alloc include/linux/sched/mm.h:303 [inline]
slab_pre_alloc_hook mm/slab.h:709 [inline]
slab_alloc_node mm/slub.c:3460 [inline]
__kmem_cache_alloc_node+0x51/0x340 mm/slub.c:3517
__do_kmalloc_node mm/slab_common.c:1022 [inline]
__kmalloc_node+0x52/0x110 mm/slab_common.c:1030
kmalloc_node include/linux/slab.h:619 [inline]
kvmalloc_node+0x99/0x1a0 mm/util.c:607
kvmalloc include/linux/slab.h:737 [inline]
ext4_xattr_inode_cache_find fs/ext4/xattr.c:1535 [inline]
ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1577 [inline]
ext4_xattr_set_entry+0x1c3d/0x3ca0 fs/ext4/xattr.c:1719
ext4_xattr_block_set+0x678/0x30e0 fs/ext4/xattr.c:1970
ext4_xattr_move_to_block fs/ext4/xattr.c:2667 [inline]
ext4_xattr_make_inode_space fs/ext4/xattr.c:2742 [inline]
ext4_expand_extra_isize_ea+0x1306/0x1b20 fs/ext4/xattr.c:2834
__ext4_expand_extra_isize+0x342/0x470 fs/ext4/inode.c:5803
ext4_try_to_expand_extra_isize fs/ext4/inode.c:5846 [inline]
__ext4_mark_inode_dirty+0x52b/0x800 fs/ext4/inode.c:5924
__ext4_unlink+0x630/0xc60 fs/ext4/namei.c:3296
ext4_unlink+0x40d/0x580 fs/ext4/namei.c:3325
vfs_unlink+0x2f1/0x900 fs/namei.c:4332
do_unlinkat+0x3da/0x6d0 fs/namei.c:4398
__do_sys_unlinkat fs/namei.c:4441 [inline]
__se_sys_unlinkat fs/namei.c:4434 [inline]
__ia32_sys_unlinkat+0xc1/0x130 fs/namei.c:4434
do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
__do_fast_syscall_32+0x61/0xe0 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

-> #0 (&ei->xattr_sem){++++}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3868 [inline]
__lock_acquire+0x2e3d/0x5de0 kernel/locking/lockdep.c:5136
lock_acquire kernel/locking/lockdep.c:5753 [inline]
lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718
down_write+0x93/0x200 kernel/locking/rwsem.c:1573
ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
ext4_xattr_set_handle+0x159/0x1420 fs/ext4/xattr.c:2371
ext4_xattr_set+0x149/0x370 fs/ext4/xattr.c:2558
__vfs_setxattr+0x173/0x1d0 fs/xattr.c:201
__vfs_setxattr_noperm+0x127/0x5e0 fs/xattr.c:235
__vfs_setxattr_locked+0x17e/0x250 fs/xattr.c:296
vfs_setxattr+0x146/0x350 fs/xattr.c:322
do_setxattr+0x142/0x170 fs/xattr.c:630
setxattr+0x159/0x170 fs/xattr.c:653
__do_sys_fsetxattr fs/xattr.c:709 [inline]
__se_sys_fsetxattr fs/xattr.c:698 [inline]
__ia32_sys_fsetxattr+0x25e/0x310 fs/xattr.c:698
do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
__do_fast_syscall_32+0x61/0xe0 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:
&ei->xattr_sem --> fs_reclaim --> jbd2_handle

Possible unsafe locking scenario:

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

*** DEADLOCK ***

3 locks held by syz-executor.2/16393:
#0: ffff88801a440410 (sb_writers#4){.+.+}-{0:0}, at: __do_sys_fsetxattr fs/xattr.c:707 [inline]
#0: ffff88801a440410 (sb_writers#4){.+.+}-{0:0}, at: __se_sys_fsetxattr fs/xattr.c:698 [inline]
#0: ffff88801a440410 (sb_writers#4){.+.+}-{0:0}, at: __ia32_sys_fsetxattr+0x17a/0x310 fs/xattr.c:698
#1: ffff88801c253600 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: inode_lock include/linux/fs.h:802 [inline]
#1: ffff88801c253600 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: vfs_setxattr+0x123/0x350 fs/xattr.c:321
#2: ffff8880444e0988 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x10d6/0x15e0 fs/jbd2/transaction.c:463

stack backtrace:
CPU: 0 PID: 16393 Comm: syz-executor.2 Not tainted 6.6.0-rc1-syzkaller-00269-ge789286468a9 #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+0xd9/0x1b0 lib/dump_stack.c:106
check_noncircular+0x311/0x3f0 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:3868 [inline]
__lock_acquire+0x2e3d/0x5de0 kernel/locking/lockdep.c:5136
lock_acquire kernel/locking/lockdep.c:5753 [inline]
lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718
down_write+0x93/0x200 kernel/locking/rwsem.c:1573
ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
ext4_xattr_set_handle+0x159/0x1420 fs/ext4/xattr.c:2371
ext4_xattr_set+0x149/0x370 fs/ext4/xattr.c:2558
__vfs_setxattr+0x173/0x1d0 fs/xattr.c:201
__vfs_setxattr_noperm+0x127/0x5e0 fs/xattr.c:235
__vfs_setxattr_locked+0x17e/0x250 fs/xattr.c:296
vfs_setxattr+0x146/0x350 fs/xattr.c:322
do_setxattr+0x142/0x170 fs/xattr.c:630
setxattr+0x159/0x170 fs/xattr.c:653
__do_sys_fsetxattr fs/xattr.c:709 [inline]
__se_sys_fsetxattr fs/xattr.c:698 [inline]
__ia32_sys_fsetxattr+0x25e/0x310 fs/xattr.c:698
do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
__do_fast_syscall_32+0x61/0xe0 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: 0023:0xf7fbe579
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:00000000f7fb95ac EFLAGS: 00000292 ORIG_RAX: 00000000000000e4
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000020000140
RDX: 0000000020000180 RSI: 0000000000000015 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
----------------
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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