Date: Wed, 22 May 2024 18:43:21 -0700
From: syzbot <syzbot+069cc167ecbee6e3e91a@...kaller.appspotmail.com>
To: chandan.babu@...cle.com, djwong@...nel.org, linux-kernel@...r.kernel.org, 
	linux-xfs@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [xfs?] possible deadlock in xfs_ilock_attr_map_shared

Hello,

syzbot found the following issue on:

HEAD commit:    4b377b4868ef kprobe/ftrace: fix build error due to bad fun..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16f19368980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=17ffd15f654c98ba
dashboard link: https://syzkaller.appspot.com/bug?extid=069cc167ecbee6e3e91a
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/80503f9339d4/disk-4b377b48.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c74a52927209/vmlinux-4b377b48.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6ea396d85317/bzImage-4b377b48.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+069cc167ecbee6e3e91a@...kaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.9.0-syzkaller-08544-g4b377b4868ef #0 Not tainted
------------------------------------------------------
syz-executor.3/11981 is trying to acquire lock:
ffffffff8e42ad40 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:312 [inline]
ffffffff8e42ad40 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:3819 [inline]
ffffffff8e42ad40 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:3900 [inline]
ffffffff8e42ad40 (fs_reclaim){+.+.}-{0:0}, at: __do_kmalloc_node mm/slub.c:4038 [inline]
ffffffff8e42ad40 (fs_reclaim){+.+.}-{0:0}, at: __kmalloc+0xb7/0x4a0 mm/slub.c:4052

but task is already holding lock:
ffff88806a1308d8 (&xfs_dir_ilock_class){++++}-{3:3}, at: xfs_ilock_attr_map_shared+0x8c/0xc0 fs/xfs/xfs_inode.c:126

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&xfs_dir_ilock_class){++++}-{3:3}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       down_write_nested+0x3d/0x50 kernel/locking/rwsem.c:1695
       xfs_reclaim_inode fs/xfs/xfs_icache.c:945 [inline]
       xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1631 [inline]
       xfs_icwalk_ag+0x120e/0x1ad0 fs/xfs/xfs_icache.c:1713
       xfs_icwalk fs/xfs/xfs_icache.c:1762 [inline]
       xfs_reclaim_inodes_nr+0x257/0x360 fs/xfs/xfs_icache.c:1011
       super_cache_scan+0x411/0x4b0 fs/super.c:227
       do_shrink_slab+0x707/0x1160 mm/shrinker.c:435
       shrink_slab_memcg mm/shrinker.c:548 [inline]
       shrink_slab+0x883/0x14d0 mm/shrinker.c:626
       shrink_one+0x453/0x880 mm/vmscan.c:4774
       shrink_many mm/vmscan.c:4835 [inline]
       lru_gen_shrink_node mm/vmscan.c:4935 [inline]
       shrink_node+0x3b17/0x4310 mm/vmscan.c:5894
       kswapd_shrink_node mm/vmscan.c:6704 [inline]
       balance_pgdat mm/vmscan.c:6895 [inline]
       kswapd+0x1882/0x38a0 mm/vmscan.c:7164
       kthread+0x2f2/0x390 kernel/kthread.c:389
       ret_from_fork+0x4d/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+0x18cb/0x58e0 kernel/locking/lockdep.c:3869
       __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __fs_reclaim_acquire mm/page_alloc.c:3698 [inline]
       fs_reclaim_acquire+0x88/0x140 mm/page_alloc.c:3712
       might_alloc include/linux/sched/mm.h:312 [inline]
       slab_pre_alloc_hook mm/slub.c:3819 [inline]
       slab_alloc_node mm/slub.c:3900 [inline]
       __do_kmalloc_node mm/slub.c:4038 [inline]
       __kmalloc+0xb7/0x4a0 mm/slub.c:4052
       kmalloc include/linux/slab.h:632 [inline]
       xfs_attr_shortform_list+0x6f3/0x17a0 fs/xfs/xfs_attr_list.c:115
       xfs_attr_list_ilocked fs/xfs/xfs_attr_list.c:527 [inline]
       xfs_attr_list+0x25b/0x350 fs/xfs/xfs_attr_list.c:547
       xfs_vn_listxattr+0x1d2/0x2c0 fs/xfs/xfs_xattr.c:314
       vfs_listxattr fs/xattr.c:493 [inline]
       listxattr+0x109/0x290 fs/xattr.c:840
       path_listxattr fs/xattr.c:864 [inline]
       __do_sys_listxattr fs/xattr.c:876 [inline]
       __se_sys_listxattr fs/xattr.c:873 [inline]
       __x64_sys_listxattr+0x176/0x240 fs/xattr.c:873
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(&xfs_dir_ilock_class);
                               lock(fs_reclaim);
                               lock(&xfs_dir_ilock_class);
  lock(fs_reclaim);

 *** DEADLOCK ***

1 lock held by syz-executor.3/11981:
 #0: ffff88806a1308d8 (&xfs_dir_ilock_class){++++}-{3:3}, at: xfs_ilock_attr_map_shared+0x8c/0xc0 fs/xfs/xfs_inode.c:126

stack backtrace:
CPU: 0 PID: 11981 Comm: syz-executor.3 Not tainted 6.9.0-syzkaller-08544-g4b377b4868ef #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 check_noncircular+0x36a/0x4a0 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+0x18cb/0x58e0 kernel/locking/lockdep.c:3869
 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
 __fs_reclaim_acquire mm/page_alloc.c:3698 [inline]
 fs_reclaim_acquire+0x88/0x140 mm/page_alloc.c:3712
 might_alloc include/linux/sched/mm.h:312 [inline]
 slab_pre_alloc_hook mm/slub.c:3819 [inline]
 slab_alloc_node mm/slub.c:3900 [inline]
 __do_kmalloc_node mm/slub.c:4038 [inline]
 __kmalloc+0xb7/0x4a0 mm/slub.c:4052
 kmalloc include/linux/slab.h:632 [inline]
 xfs_attr_shortform_list+0x6f3/0x17a0 fs/xfs/xfs_attr_list.c:115
 xfs_attr_list_ilocked fs/xfs/xfs_attr_list.c:527 [inline]
 xfs_attr_list+0x25b/0x350 fs/xfs/xfs_attr_list.c:547
 xfs_vn_listxattr+0x1d2/0x2c0 fs/xfs/xfs_xattr.c:314
 vfs_listxattr fs/xattr.c:493 [inline]
 listxattr+0x109/0x290 fs/xattr.c:840
 path_listxattr fs/xattr.c:864 [inline]
 __do_sys_listxattr fs/xattr.c:876 [inline]
 __se_sys_listxattr fs/xattr.c:873 [inline]
 __x64_sys_listxattr+0x176/0x240 fs/xattr.c:873
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa1f3a7cee9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa1f48160c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000c2
RAX: ffffffffffffffda RBX: 00007fa1f3bac050 RCX: 00007fa1f3a7cee9
RDX: 0000000000000011 RSI: 0000000000000000 RDI: 0000000020000140
RBP: 00007fa1f3ac949e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007fa1f3bac050 R15: 00007ffdecee0588
 </TASK>


---
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