[syzbot] [ext4?] possible deadlock in ext4_inline_data_truncate

From: syzbot
Date: Wed Mar 22 2023 - 23:15:01 EST

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Hello,

syzbot found the following issue on:

HEAD commit: 534293368afa Merge tag 'kbuild-fixes-v6.3' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12247281c80000
kernel config: https://syzkaller.appspot.com/x/.config?x=e23c4bcf73cdc669
dashboard link: https://syzkaller.appspot.com/bug?extid=b8e6e6822d493a4630f3
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+b8e6e6822d493a4630f3@xxxxxxxxxxxxxxxxxxxxxxxxx

EXT4-fs (loop2): 1 truncate cleaned up
EXT4-fs (loop2): mounted filesystem 00000000-0000-0000-0000-000000000000 without journal. Quota mode: writeback.
======================================================
WARNING: possible circular locking dependency detected
6.3.0-rc2-syzkaller-00387-g534293368afa #0 Not tainted
------------------------------------------------------
syz-executor.2/1999 is trying to acquire lock:
ffff888029121ee0 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
ffff888029121ee0 (&ei->xattr_sem){++++}-{3:3}, at: ext4_inline_data_truncate+0x1a8/0xd70 fs/ext4/inline.c:1932

but task is already holding lock:
ffff88801ae60650 (sb_internal){.+.+}-{0:0}, at: evict+0x2ed/0x6b0 fs/inode.c:665

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (sb_internal){.+.+}-{0:0}:
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1477 [inline]
sb_start_intwrite include/linux/fs.h:1599 [inline]
ext4_evict_inode+0x114b/0x1ca0 fs/ext4/inode.c:240
evict+0x2ed/0x6b0 fs/inode.c:665
iput_final fs/inode.c:1748 [inline]
iput.part.0+0x50a/0x740 fs/inode.c:1774
iput+0x5c/0x80 fs/inode.c:1764
dentry_unlink_inode+0x2b1/0x460 fs/dcache.c:401
__dentry_kill+0x3c0/0x640 fs/dcache.c:607
shrink_dentry_list+0x12c/0x4f0 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+0x428/0xaa0 mm/vmscan.c:853
shrink_slab_memcg mm/vmscan.c:922 [inline]
shrink_slab+0x388/0x660 mm/vmscan.c:1001
shrink_one+0x502/0x810 mm/vmscan.c:5343
shrink_many mm/vmscan.c:5394 [inline]
lru_gen_shrink_node mm/vmscan.c:5511 [inline]
shrink_node+0x2064/0x35f0 mm/vmscan.c:6459
kswapd_shrink_node mm/vmscan.c:7262 [inline]
balance_pgdat+0xa02/0x1ac0 mm/vmscan.c:7452
kswapd+0x677/0xd60 mm/vmscan.c:7712
kthread+0x2e8/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

-> #1 (fs_reclaim){+.+.}-{0:0}:
__fs_reclaim_acquire mm/page_alloc.c:4716 [inline]
fs_reclaim_acquire+0x11d/0x160 mm/page_alloc.c:4730
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook mm/slab.h:728 [inline]
slab_alloc_node mm/slub.c:3434 [inline]
__kmem_cache_alloc_node+0x41/0x320 mm/slub.c:3491
__do_kmalloc_node mm/slab_common.c:966 [inline]
__kmalloc_node+0x51/0x1a0 mm/slab_common.c:974
kmalloc_node include/linux/slab.h:610 [inline]
kvmalloc_node+0xa2/0x1a0 mm/util.c:603
kvmalloc include/linux/slab.h:737 [inline]
ext4_xattr_inode_cache_find fs/ext4/xattr.c:1552 [inline]
ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1595 [inline]
ext4_xattr_set_entry+0x1d82/0x39e0 fs/ext4/xattr.c:1737
ext4_xattr_block_set+0x618/0x3030 fs/ext4/xattr.c:1974
ext4_xattr_move_to_block fs/ext4/xattr.c:2668 [inline]
ext4_xattr_make_inode_space fs/ext4/xattr.c:2743 [inline]
ext4_expand_extra_isize_ea+0xa84/0x1880 fs/ext4/xattr.c:2835
__ext4_expand_extra_isize+0x33e/0x470 fs/ext4/inode.c:5960
ext4_try_to_expand_extra_isize fs/ext4/inode.c:6003 [inline]
__ext4_mark_inode_dirty+0x51b/0x800 fs/ext4/inode.c:6081
__ext4_unlink+0x667/0xcd0 fs/ext4/namei.c:3269
ext4_unlink+0x41f/0x590 fs/ext4/namei.c:3298
vfs_unlink+0x355/0x930 fs/namei.c:4250
do_unlinkat+0x3df/0x670 fs/namei.c:4316
__do_sys_unlinkat fs/namei.c:4359 [inline]
__se_sys_unlinkat fs/namei.c:4352 [inline]
__ia32_sys_unlinkat+0xc1/0x130 fs/namei.c:4352
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

-> #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+0x2ec7/0x5d40 kernel/locking/lockdep.c:5056
lock_acquire kernel/locking/lockdep.c:5669 [inline]
lock_acquire+0x1af/0x520 kernel/locking/lockdep.c:5634
down_write+0x92/0x200 kernel/locking/rwsem.c:1573
ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
ext4_inline_data_truncate+0x1a8/0xd70 fs/ext4/inline.c:1932
ext4_truncate+0x992/0x1340 fs/ext4/inode.c:4298
ext4_evict_inode+0xb9f/0x1ca0 fs/ext4/inode.c:286
evict+0x2ed/0x6b0 fs/inode.c:665
iput_final fs/inode.c:1748 [inline]
iput.part.0+0x50a/0x740 fs/inode.c:1774
iput+0x5c/0x80 fs/inode.c:1764
do_unlinkat+0x42e/0x670 fs/namei.c:4323
__do_sys_unlinkat fs/namei.c:4359 [inline]
__se_sys_unlinkat fs/namei.c:4352 [inline]
__ia32_sys_unlinkat+0xc1/0x130 fs/namei.c:4352
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:
&ei->xattr_sem --> fs_reclaim --> sb_internal

Possible unsafe locking scenario:

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

*** DEADLOCK ***

2 locks held by syz-executor.2/1999:
#0: ffff88801ae60460 (sb_writers#4){.+.+}-{0:0}, at: do_unlinkat+0x18c/0x670 fs/namei.c:4297
#1: ffff88801ae60650 (sb_internal){.+.+}-{0:0}, at: evict+0x2ed/0x6b0 fs/inode.c:665

stack backtrace:
CPU: 0 PID: 1999 Comm: syz-executor.2 Not tainted 6.3.0-rc2-syzkaller-00387-g534293368afa #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+0xd9/0x150 lib/dump_stack.c:106
check_noncircular+0x25f/0x2e0 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+0x2ec7/0x5d40 kernel/locking/lockdep.c:5056
lock_acquire kernel/locking/lockdep.c:5669 [inline]
lock_acquire+0x1af/0x520 kernel/locking/lockdep.c:5634
down_write+0x92/0x200 kernel/locking/rwsem.c:1573
ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
ext4_inline_data_truncate+0x1a8/0xd70 fs/ext4/inline.c:1932
ext4_truncate+0x992/0x1340 fs/ext4/inode.c:4298
ext4_evict_inode+0xb9f/0x1ca0 fs/ext4/inode.c:286
evict+0x2ed/0x6b0 fs/inode.c:665
iput_final fs/inode.c:1748 [inline]
iput.part.0+0x50a/0x740 fs/inode.c:1774
iput+0x5c/0x80 fs/inode.c:1764
do_unlinkat+0x42e/0x670 fs/namei.c:4323
__do_sys_unlinkat fs/namei.c:4359 [inline]
__se_sys_unlinkat fs/namei.c:4352 [inline]
__ia32_sys_unlinkat+0xc1/0x130 fs/namei.c:4352
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: 0023:0xf7fcf579
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:00000000f7fca5cc EFLAGS: 00000296 ORIG_RAX: 000000000000012d
RAX: ffffffffffffffda RBX: 00000000ffffff9c RCX: 00000000200003c0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 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 retq
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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Previous message: syzbot: "Re: [syzbot] [sctp?] general protection fault in sctp_outq_tail"
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