possible deadlock in jffs2_xattr_delete_inode

Status: upstream: reported on 2026/09/07 01:55
Subsystems: jffs2
[Documentation on labels]
Reported-by: syzbot+fdfd8fdf716c90baef0f@syzkaller.appspotmail.com
First crash: 4d03h, last: 4d03h
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
6f73a069 assessment-security 💥 possible deadlock in jffs2_xattr_delete_inode 2026/09/06 01:01 2026/09/06 01:01 2026/09/06 01:01 4f7b22a0
57044f57 assessment-security 💥 possible deadlock in jffs2_xattr_delete_inode 2026/09/04 13:34 2026/09/04 13:34 2026/09/04 13:34 801f0966
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Title Replies (including bot) Last reply
[syzbot] [jffs2?] possible deadlock in jffs2_xattr_delete_inode 0 (1) 2026/09/07 01:55

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kswapd0/111 is trying to acquire lock:
ffff8880266529d8 (&c->xattr_sem){++++}-{4:4}, at: jffs2_xattr_delete_inode+0x83/0x130 fs/jffs2/xattr.c:605

but task is already holding lock:
ffffffff8efc8ce0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0xbce/0x1f00 mm/vmscan.c:7292

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (fs_reclaim){+.+.}-{0:0}:
       lock_acquire kernel/locking/lockdep.c:5908 [inline]
       lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865
       __fs_reclaim_acquire mm/page_alloc.c:4375 [inline]
       fs_reclaim_acquire+0xc4/0x100 mm/page_alloc.c:4389
       might_alloc include/linux/sched/mm.h:316 [inline]
       slab_pre_alloc_hook mm/slub.c:4636 [inline]
       slab_alloc_node mm/slub.c:4974 [inline]
       kmem_cache_alloc_noprof+0x63/0x6a0 mm/slub.c:5010
       jffs2_alloc_xattr_datum+0x1c/0xe0 fs/jffs2/malloc.c:264
       create_xattr_datum fs/jffs2/xattr.c:363 [inline]
       do_jffs2_setxattr+0x6f0/0x1610 fs/jffs2/xattr.c:1175
       __vfs_setxattr+0x175/0x1e0 fs/xattr.c:223
       __vfs_setxattr_noperm+0x127/0x660 fs/xattr.c:257
       __vfs_setxattr_locked+0x127/0x2b0 fs/xattr.c:318
       vfs_setxattr+0x14a/0x390 fs/xattr.c:344
       ovl_do_setxattr fs/overlayfs/overlayfs.h:324 [inline]
       ovl_setxattr fs/overlayfs/overlayfs.h:336 [inline]
       ovl_make_workdir fs/overlayfs/super.c:724 [inline]
       ovl_get_workdir fs/overlayfs/super.c:836 [inline]
       ovl_fill_super_creds fs/overlayfs/super.c:1449 [inline]
       ovl_fill_super+0x1320/0x5ea0 fs/overlayfs/super.c:1561
       vfs_get_super fs/super.c:1405 [inline]
       get_tree_nodev+0xdd/0x190 fs/super.c:1424
       vfs_get_tree+0x92/0x320 fs/super.c:1947
       fc_mount fs/namespace.c:1198 [inline]
       do_new_mount_fc fs/namespace.c:3772 [inline]
       do_new_mount fs/namespace.c:3848 [inline]
       path_mount+0x7d0/0x24c0 fs/namespace.c:4168
       do_mount fs/namespace.c:4181 [inline]
       __do_sys_mount fs/namespace.c:4397 [inline]
       __se_sys_mount fs/namespace.c:4374 [inline]
       __ia32_sys_mount+0x292/0x310 fs/namespace.c:4374
       do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:79 [inline]
       __do_fast_syscall_32+0x13a/0x8b0 arch/x86/entry/syscall_32.c:291
       do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:316
       entry_SYSENTER_compat_after_hwframe+0x84/0x8e

-> #0 (&c->xattr_sem){++++}-{4:4}:
       check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3181
       check_prevs_add kernel/locking/lockdep.c:3300 [inline]
       validate_chain kernel/locking/lockdep.c:3924 [inline]
       __lock_acquire+0x1492/0x1ec0 kernel/locking/lockdep.c:5254
       lock_acquire kernel/locking/lockdep.c:5908 [inline]
       lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865
       down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1631
       jffs2_xattr_delete_inode+0x83/0x130 fs/jffs2/xattr.c:605
       jffs2_do_clear_inode+0x50/0x470 fs/jffs2/readinode.c:1418
       evict+0x3c2/0xad0 fs/inode.c:822
       iput_final fs/inode.c:2015 [inline]
       iput.part.0+0x989/0x1050 fs/inode.c:2064
       iput+0x35/0x40 fs/inode.c:2030
       dentry_unlink_inode+0x284/0x470 fs/dcache.c:479
       dentry_kill+0x25d/0xc20 fs/dcache.c:826
       finish_dput fs/dcache.c:1001 [inline]
       dput.part.0+0xd7/0x240 fs/dcache.c:1042
       dput+0x1f/0x30 fs/dcache.c:1037
       ovl_destroy_inode+0x3e/0x190 fs/overlayfs/super.c:217
       destroy_inode+0xcb/0x1c0 fs/inode.c:387
       evict+0x599/0xad0 fs/inode.c:846
       iput_final fs/inode.c:2015 [inline]
       iput.part.0+0x989/0x1050 fs/inode.c:2064
       iput+0x35/0x40 fs/inode.c:2030
       dentry_unlink_inode+0x284/0x470 fs/dcache.c:479
       dentry_kill+0x25d/0xc20 fs/dcache.c:826
       shrink_kill fs/dcache.c:1275 [inline]
       shrink_dentry_list+0x1e8/0x310 fs/dcache.c:1292
       prune_dcache_sb+0xea/0x150 fs/dcache.c:1374
       super_cache_scan+0x361/0x5c0 fs/super.c:238
       do_shrink_slab+0x416/0x1200 mm/shrinker.c:443
       shrink_slab_memcg mm/shrinker.c:560 [inline]
       shrink_slab+0xa82/0x12e0 mm/shrinker.c:638
       shrink_one+0x398/0x850 mm/vmscan.c:5119
       shrink_many mm/vmscan.c:5180 [inline]
       lru_gen_shrink_node mm/vmscan.c:5258 [inline]
       shrink_node+0x2b20/0x4320 mm/vmscan.c:6247
       kswapd_shrink_node mm/vmscan.c:7101 [inline]
       balance_pgdat+0xb20/0x1f00 mm/vmscan.c:7279
       kswapd+0x556/0xb50 mm/vmscan.c:7555
       kthread+0x373/0x450 kernel/kthread.c:436
       ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(fs_reclaim);
                               lock(&c->xattr_sem);
                               lock(fs_reclaim);
  lock(&c->xattr_sem);

 *** DEADLOCK ***

locks held by kswapd0/111: 2, last CPU#2:
 #0: ffffffff8efc8ce0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0xbce/0x1f00 mm/vmscan.c:7292
 #1: ffff888025eec0e8 (&type->s_umount_key#56){++++}-{4:4}, at: super_trylock_shared fs/super.c:688 [inline]
 #1: ffff888025eec0e8 (&type->s_umount_key#56){++++}-{4:4}, at: super_cache_scan+0x9b/0x5c0 fs/super.c:213

stack backtrace:
CPU: 2 UID: 0 PID: 111 Comm: kswapd0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_circular_bug.cold+0x178/0x1be kernel/locking/lockdep.c:2059
 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2191
 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3181
 check_prevs_add kernel/locking/lockdep.c:3300 [inline]
 validate_chain kernel/locking/lockdep.c:3924 [inline]
 __lock_acquire+0x1492/0x1ec0 kernel/locking/lockdep.c:5254
 lock_acquire kernel/locking/lockdep.c:5908 [inline]
 lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865
 down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1631
 jffs2_xattr_delete_inode+0x83/0x130 fs/jffs2/xattr.c:605
 jffs2_do_clear_inode+0x50/0x470 fs/jffs2/readinode.c:1418
 evict+0x3c2/0xad0 fs/inode.c:822
 iput_final fs/inode.c:2015 [inline]
 iput.part.0+0x989/0x1050 fs/inode.c:2064
 iput+0x35/0x40 fs/inode.c:2030
 dentry_unlink_inode+0x284/0x470 fs/dcache.c:479
 dentry_kill+0x25d/0xc20 fs/dcache.c:826
 finish_dput fs/dcache.c:1001 [inline]
 dput.part.0+0xd7/0x240 fs/dcache.c:1042
 dput+0x1f/0x30 fs/dcache.c:1037
 ovl_destroy_inode+0x3e/0x190 fs/overlayfs/super.c:217
 destroy_inode+0xcb/0x1c0 fs/inode.c:387
 evict+0x599/0xad0 fs/inode.c:846
 iput_final fs/inode.c:2015 [inline]
 iput.part.0+0x989/0x1050 fs/inode.c:2064
 iput+0x35/0x40 fs/inode.c:2030
 dentry_unlink_inode+0x284/0x470 fs/dcache.c:479
 dentry_kill+0x25d/0xc20 fs/dcache.c:826
 shrink_kill fs/dcache.c:1275 [inline]
 shrink_dentry_list+0x1e8/0x310 fs/dcache.c:1292
 prune_dcache_sb+0xea/0x150 fs/dcache.c:1374
 super_cache_scan+0x361/0x5c0 fs/super.c:238
 do_shrink_slab+0x416/0x1200 mm/shrinker.c:443
 shrink_slab_memcg mm/shrinker.c:560 [inline]
 shrink_slab+0xa82/0x12e0 mm/shrinker.c:638
 shrink_one+0x398/0x850 mm/vmscan.c:5119
 shrink_many mm/vmscan.c:5180 [inline]
 lru_gen_shrink_node mm/vmscan.c:5258 [inline]
 shrink_node+0x2b20/0x4320 mm/vmscan.c:6247
 kswapd_shrink_node mm/vmscan.c:7101 [inline]
 balance_pgdat+0xb20/0x1f00 mm/vmscan.c:7279
 kswapd+0x556/0xb50 mm/vmscan.c:7555
 kthread+0x373/0x450 kernel/kthread.c:436
 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/03 01:49 upstream 940de590b839 6a988719 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in jffs2_xattr_delete_inode
* Struck through repros no longer work on HEAD.