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Message-ID: <0000000000004332130618548876@google.com>
Date: Mon, 13 May 2024 04:53:22 -0700
From: syzbot <syzbot+4247fb9b4517c79e3b57@...kaller.appspotmail.com>
To: adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com, tytso@....edu
Subject: [syzbot] [ext4?] possible deadlock in ext4_xattr_set_handle (5)

Hello,

syzbot found the following issue on:

HEAD commit:    45db3ab70092 Merge tag '6.9-rc7-ksmbd-fixes' of git://git...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=144a905c980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a450595960709c8
dashboard link: https://syzkaller.appspot.com/bug?extid=4247fb9b4517c79e3b57
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-45db3ab7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c94d1aa6cd96/vmlinux-45db3ab7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f9daddfda2f1/bzImage-45db3ab7.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4247fb9b4517c79e3b57@...kaller.appspotmail.com

EXT4-fs (loop3): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
======================================================
WARNING: possible circular locking dependency detected
6.9.0-rc7-syzkaller-00056-g45db3ab70092 #0 Not tainted
------------------------------------------------------
syz-executor.3/30481 is trying to acquire lock:
ffffffff8d937180 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:312 [inline]
ffffffff8d937180 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:3752 [inline]
ffffffff8d937180 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:3833 [inline]
ffffffff8d937180 (fs_reclaim){+.+.}-{0:0}, at: __do_kmalloc_node mm/slub.c:3971 [inline]
ffffffff8d937180 (fs_reclaim){+.+.}-{0:0}, at: __kmalloc_node+0xbb/0x480 mm/slub.c:3979

but task is already holding lock:
ffff88802a241ec8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
ffff88802a241ec8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_xattr_set_handle+0x156/0x16d0 fs/ext4/xattr.c:2358

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&ei->xattr_sem){++++}-{3:3}:
       down_write+0x3a/0x50 kernel/locking/rwsem.c:1579
       ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
       ext4_xattr_set_handle+0x156/0x16d0 fs/ext4/xattr.c:2358
       ext4_xattr_set+0x149/0x380 fs/ext4/xattr.c:2545
       __vfs_setxattr+0x173/0x1e0 fs/xattr.c:200
       __vfs_setxattr_noperm+0x127/0x5e0 fs/xattr.c:234
       __vfs_setxattr_locked+0x182/0x260 fs/xattr.c:295
       vfs_setxattr+0x146/0x350 fs/xattr.c:321
       do_setxattr+0x146/0x170 fs/xattr.c:629
       setxattr+0x15d/0x180 fs/xattr.c:652
       path_setxattr+0x179/0x1e0 fs/xattr.c:671
       __do_sys_lsetxattr fs/xattr.c:694 [inline]
       __se_sys_lsetxattr fs/xattr.c:690 [inline]
       __ia32_sys_lsetxattr+0xbd/0x160 fs/xattr.c:690
       do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
       __do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:386
       do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
       entry_SYSENTER_compat_after_hwframe+0x84/0x8e

-> #2 (jbd2_handle){++++}-{0:0}:
       start_this_handle+0x1101/0x15e0 fs/jbd2/transaction.c:463
       jbd2__journal_start+0x394/0x6a0 fs/jbd2/transaction.c:520
       __ext4_journal_start_sb+0x358/0x660 fs/ext4/ext4_jbd2.c:112
       ext4_sample_last_mounted fs/ext4/file.c:837 [inline]
       ext4_file_open+0x636/0xc80 fs/ext4/file.c:866
       do_dentry_open+0x8da/0x18c0 fs/open.c:955
       do_open fs/namei.c:3642 [inline]
       path_openat+0x1dfb/0x2990 fs/namei.c:3799
       do_filp_open+0x1dc/0x430 fs/namei.c:3826
       do_sys_openat2+0x17a/0x1e0 fs/open.c:1406
       do_sys_open fs/open.c:1421 [inline]
       __do_sys_openat fs/open.c:1437 [inline]
       __se_sys_openat fs/open.c:1432 [inline]
       __x64_sys_openat+0x175/0x210 fs/open.c:1432
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcf/0x260 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (sb_internal){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1664 [inline]
       sb_start_intwrite include/linux/fs.h:1847 [inline]
       ext4_evict_inode+0xd7b/0x17d0 fs/ext4/inode.c:212
       evict+0x2ed/0x6c0 fs/inode.c:667
       iput_final fs/inode.c:1741 [inline]
       iput.part.0+0x5a8/0x7f0 fs/inode.c:1767
       iput+0x5c/0x80 fs/inode.c:1757
       dentry_unlink_inode+0x295/0x440 fs/dcache.c:400
       __dentry_kill+0x1d0/0x600 fs/dcache.c:603
       shrink_kill fs/dcache.c:1048 [inline]
       shrink_dentry_list+0x140/0x5d0 fs/dcache.c:1075
       prune_dcache_sb+0xeb/0x150 fs/dcache.c:1156
       super_cache_scan+0x32a/0x550 fs/super.c:221
       do_shrink_slab+0x44f/0x11c0 mm/shrinker.c:435
       shrink_slab_memcg mm/shrinker.c:548 [inline]
       shrink_slab+0xa87/0x1310 mm/shrinker.c:626
       shrink_one+0x493/0x7c0 mm/vmscan.c:4774
       shrink_many mm/vmscan.c:4835 [inline]
       lru_gen_shrink_node+0x89f/0x1750 mm/vmscan.c:4935
       shrink_node mm/vmscan.c:5894 [inline]
       kswapd_shrink_node mm/vmscan.c:6704 [inline]
       balance_pgdat+0x10d1/0x1a10 mm/vmscan.c:6895
       kswapd+0x5ea/0xbf0 mm/vmscan.c:7164
       kthread+0x2c1/0x3a0 kernel/kthread.c:388
       ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #0 (fs_reclaim){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137
       lock_acquire kernel/locking/lockdep.c:5754 [inline]
       lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719
       __fs_reclaim_acquire mm/page_alloc.c:3698 [inline]
       fs_reclaim_acquire+0x102/0x160 mm/page_alloc.c:3712
       might_alloc include/linux/sched/mm.h:312 [inline]
       slab_pre_alloc_hook mm/slub.c:3752 [inline]
       slab_alloc_node mm/slub.c:3833 [inline]
       __do_kmalloc_node mm/slub.c:3971 [inline]
       __kmalloc_node+0xbb/0x480 mm/slub.c:3979
       kmalloc_node include/linux/slab.h:648 [inline]
       kvmalloc_node+0x9d/0x1a0 mm/util.c:634
       kvmalloc include/linux/slab.h:766 [inline]
       ext4_xattr_inode_cache_find fs/ext4/xattr.c:1535 [inline]
       ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1581 [inline]
       ext4_xattr_set_entry+0xdc3/0x3b20 fs/ext4/xattr.c:1718
       ext4_xattr_block_set+0xd07/0x3080 fs/ext4/xattr.c:2037
       ext4_xattr_set_handle+0xf24/0x16d0 fs/ext4/xattr.c:2443
       ext4_xattr_set+0x149/0x380 fs/ext4/xattr.c:2545
       __vfs_setxattr+0x173/0x1e0 fs/xattr.c:200
       __vfs_setxattr_noperm+0x127/0x5e0 fs/xattr.c:234
       __vfs_setxattr_locked+0x182/0x260 fs/xattr.c:295
       vfs_setxattr+0x146/0x350 fs/xattr.c:321
       do_setxattr+0x146/0x170 fs/xattr.c:629
       setxattr+0x15d/0x180 fs/xattr.c:652
       path_setxattr+0x179/0x1e0 fs/xattr.c:671
       __do_sys_setxattr fs/xattr.c:687 [inline]
       __se_sys_setxattr fs/xattr.c:683 [inline]
       __ia32_sys_setxattr+0xc0/0x160 fs/xattr.c:683
       do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
       __do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:386
       do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
       entry_SYSENTER_compat_after_hwframe+0x84/0x8e

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.3/30481:
 #0: ffff888076954420 (sb_writers#4){.+.+}-{0:0}, at: path_setxattr+0xc3/0x1e0 fs/xattr.c:669
 #1: ffff88802a242200 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:795 [inline]
 #1: ffff88802a242200 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: vfs_setxattr+0x123/0x350 fs/xattr.c:320
 #2: ffff88802a241ec8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
 #2: ffff88802a241ec8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_xattr_set_handle+0x156/0x16d0 fs/ext4/xattr.c:2358

stack backtrace:
CPU: 0 PID: 30481 Comm: syz-executor.3 Not tainted 6.9.0-rc7-syzkaller-00056-g45db3ab70092 #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+0x116/0x1f0 lib/dump_stack.c:114
 check_noncircular+0x31a/0x400 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:3869 [inline]
 __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137
 lock_acquire kernel/locking/lockdep.c:5754 [inline]
 lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719
 __fs_reclaim_acquire mm/page_alloc.c:3698 [inline]
 fs_reclaim_acquire+0x102/0x160 mm/page_alloc.c:3712
 might_alloc include/linux/sched/mm.h:312 [inline]
 slab_pre_alloc_hook mm/slub.c:3752 [inline]
 slab_alloc_node mm/slub.c:3833 [inline]
 __do_kmalloc_node mm/slub.c:3971 [inline]
 __kmalloc_node+0xbb/0x480 mm/slub.c:3979
 kmalloc_node include/linux/slab.h:648 [inline]
 kvmalloc_node+0x9d/0x1a0 mm/util.c:634
 kvmalloc include/linux/slab.h:766 [inline]
 ext4_xattr_inode_cache_find fs/ext4/xattr.c:1535 [inline]
 ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1581 [inline]
 ext4_xattr_set_entry+0xdc3/0x3b20 fs/ext4/xattr.c:1718
 ext4_xattr_block_set+0xd07/0x3080 fs/ext4/xattr.c:2037
 ext4_xattr_set_handle+0xf24/0x16d0 fs/ext4/xattr.c:2443
 ext4_xattr_set+0x149/0x380 fs/ext4/xattr.c:2545
 __vfs_setxattr+0x173/0x1e0 fs/xattr.c:200
 __vfs_setxattr_noperm+0x127/0x5e0 fs/xattr.c:234
 __vfs_setxattr_locked+0x182/0x260 fs/xattr.c:295
 vfs_setxattr+0x146/0x350 fs/xattr.c:321
 do_setxattr+0x146/0x170 fs/xattr.c:629
 setxattr+0x15d/0x180 fs/xattr.c:652
 path_setxattr+0x179/0x1e0 fs/xattr.c:671
 __do_sys_setxattr fs/xattr.c:687 [inline]
 __se_sys_setxattr fs/xattr.c:683 [inline]
 __ia32_sys_setxattr+0xc0/0x160 fs/xattr.c:683
 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
 __do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:386
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf72c6579
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:00000000f5eb85ac EFLAGS: 00000292 ORIG_RAX: 00000000000000e2
RAX: ffffffffffffffda RBX: 0000000020000200 RCX: 00000000200001c0
RDX: 0000000020001400 RSI: 0000000000000835 RDI: 0000000000000000
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


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@...glegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

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