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

From: syzbot
Date: Tue Jan 24 2023 - 19:29:00 EST

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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+edce54daffee36421b4c@xxxxxxxxxxxxxxxxxxxxxxxxx

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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Next message: Naresh Kamboju: "Re: [PATCH 5.15 000/117] 5.15.90-rc2 review"
Previous message: Paul E. McKenney: "[PATCH v2 clocksource 2/7] clocksource: Loosen clocksource watchdog constraints"
Next in thread: Jan Kara: "Re: [syzbot] [ext4?] possible deadlock in ext4_xattr_set_handle (3)"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]