possible deadlock in xfs_ilock_attr_map_shared (2)

Status: fixed on 2025/10/29 21:02
Subsystems: kasan
[Documentation on labels]
Reported-by: syzbot+3470c9ffee63e4abafeb@syzkaller.appspotmail.com
Fix commit: 79357cd06d41 mm/vmalloc, mm/kasan: respect gfp mask in kasan_populate_vmalloc()
First crash: 381d, last: 327d
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
Re: [PATCH] mm/vmalloc, mm/kasan: respect gfp mask in kasan_populate_vmalloc() 1 (1) 2025/09/05 14:35
[syzbot] [xfs?] possible deadlock in xfs_ilock_attr_map_shared (2) 4 (5) 2025/08/11 13:38
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in xfs_ilock_attr_map_shared xfs 4 C 1210 604d 793d 0/29 auto-obsoleted due to no activity on 2025/06/11 21:18

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.0/5355 is trying to acquire lock:
ffffffff8e241600 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:318 [inline]
ffffffff8e241600 (fs_reclaim){+.+.}-{0:0}, at: prepare_alloc_pages+0x153/0x610 mm/page_alloc.c:4916

but task is already holding lock:
ffff888012326018 (&xfs_nondir_ilock_class){++++}-{4:4}, at: xfs_ilock_attr_map_shared+0x92/0xd0 fs/xfs/xfs_inode.c:85

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&xfs_nondir_ilock_class){++++}-{4:4}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       down_write_nested+0x9d/0x200 kernel/locking/rwsem.c:1706
       xfs_reclaim_inode fs/xfs/xfs_icache.c:1042 [inline]
       xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1734 [inline]
       xfs_icwalk_ag+0x12c5/0x1ab0 fs/xfs/xfs_icache.c:1816
       xfs_icwalk fs/xfs/xfs_icache.c:1864 [inline]
       xfs_reclaim_inodes_nr+0x1e3/0x260 fs/xfs/xfs_icache.c:1108
       super_cache_scan+0x41b/0x4b0 fs/super.c:228
       do_shrink_slab+0x6ef/0x1110 mm/shrinker.c:437
       shrink_slab+0xd74/0x10d0 mm/shrinker.c:664
       shrink_one+0x28a/0x7c0 mm/vmscan.c:4954
       shrink_many mm/vmscan.c:5015 [inline]
       lru_gen_shrink_node mm/vmscan.c:5093 [inline]
       shrink_node+0x314e/0x3760 mm/vmscan.c:6078
       kswapd_shrink_node mm/vmscan.c:6938 [inline]
       balance_pgdat mm/vmscan.c:7121 [inline]
       kswapd+0x147c/0x2830 mm/vmscan.c:7386
       kthread+0x70e/0x8a0 kernel/kthread.c:463
       ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #0 (fs_reclaim){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
       __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       __fs_reclaim_acquire mm/page_alloc.c:4234 [inline]
       fs_reclaim_acquire+0x72/0x100 mm/page_alloc.c:4248
       might_alloc include/linux/sched/mm.h:318 [inline]
       prepare_alloc_pages+0x153/0x610 mm/page_alloc.c:4916
       __alloc_frozen_pages_noprof+0x123/0x370 mm/page_alloc.c:5137
       alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
       alloc_frozen_pages_noprof mm/mempolicy.c:2487 [inline]
       alloc_pages_noprof+0xa9/0x190 mm/mempolicy.c:2507
       get_free_pages_noprof+0xf/0x80 mm/page_alloc.c:5207
       __kasan_populate_vmalloc mm/kasan/shadow.c:362 [inline]
       kasan_populate_vmalloc+0x33/0x1a0 mm/kasan/shadow.c:417
       alloc_vmap_area+0xd51/0x1490 mm/vmalloc.c:2092
       __get_vm_area_node+0x1f8/0x300 mm/vmalloc.c:3187
       __vmalloc_node_range_noprof+0x301/0x12f0 mm/vmalloc.c:3853
       __vmalloc_node_noprof mm/vmalloc.c:3956 [inline]
       __vmalloc_noprof+0xb1/0xf0 mm/vmalloc.c:3970
       xfs_buf_alloc_backing_mem fs/xfs/xfs_buf.c:239 [inline]
       xfs_buf_alloc+0xed3/0x1d40 fs/xfs/xfs_buf.c:312
       xfs_buf_find_insert+0xab/0x1470 fs/xfs/xfs_buf.c:505
       xfs_buf_get_map+0x1264/0x1860 fs/xfs/xfs_buf.c:609
       xfs_buf_read_map+0x82/0xa50 fs/xfs/xfs_buf.c:702
       xfs_buf_read fs/xfs/xfs_buf.h:259 [inline]
       xfs_attr_rmtval_get+0x5b3/0xba0 fs/xfs/libxfs/xfs_attr_remote.c:434
       xfs_attr_node_get+0x150/0x4f0 fs/xfs/libxfs/xfs_attr.c:1532
       xfs_attr_get_ilocked+0x330/0x410 fs/xfs/libxfs/xfs_attr.c:248
       xfs_attr_get+0x492/0x5e0 fs/xfs/libxfs/xfs_attr.c:289
       xfs_xattr_get+0x125/0x1c0 fs/xfs/xfs_xattr.c:150
       vfs_getxattr_alloc+0x52c/0x580 fs/xattr.c:404
       ima_read_xattr+0x38/0x60 security/integrity/ima/ima_appraise.c:230
       process_measurement+0xfd7/0x1a40 security/integrity/ima/ima_main.c:386
       ima_file_check+0xd7/0x120 security/integrity/ima/ima_main.c:633
       security_file_post_open+0xbb/0x290 security/security.c:3160
       do_open fs/namei.c:3889 [inline]
       path_openat+0x2f26/0x3830 fs/namei.c:4046
       do_filp_open+0x1fa/0x410 fs/namei.c:4073
       do_sys_openat2+0x121/0x1c0 fs/open.c:1435
       do_sys_open fs/open.c:1450 [inline]
       __do_sys_openat fs/open.c:1466 [inline]
       __se_sys_openat fs/open.c:1461 [inline]
       __x64_sys_openat+0x138/0x170 fs/open.c:1461
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

2 locks held by syz.0.0/5355:
 #0: ffff8880444046c8 (&ima_iint_mutex_key[depth]){+.+.}-{4:4}, at: process_measurement+0x74b/0x1a40 security/integrity/ima/ima_main.c:299
 #1: ffff888012326018 (&xfs_nondir_ilock_class){++++}-{4:4}, at: xfs_ilock_attr_map_shared+0x92/0xd0 fs/xfs/xfs_inode.c:85

stack backtrace:
CPU: 0 UID: 0 PID: 5355 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043
 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
 __fs_reclaim_acquire mm/page_alloc.c:4234 [inline]
 fs_reclaim_acquire+0x72/0x100 mm/page_alloc.c:4248
 might_alloc include/linux/sched/mm.h:318 [inline]
 prepare_alloc_pages+0x153/0x610 mm/page_alloc.c:4916
 __alloc_frozen_pages_noprof+0x123/0x370 mm/page_alloc.c:5137
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
 alloc_frozen_pages_noprof mm/mempolicy.c:2487 [inline]
 alloc_pages_noprof+0xa9/0x190 mm/mempolicy.c:2507
 get_free_pages_noprof+0xf/0x80 mm/page_alloc.c:5207
 __kasan_populate_vmalloc mm/kasan/shadow.c:362 [inline]
 kasan_populate_vmalloc+0x33/0x1a0 mm/kasan/shadow.c:417
 alloc_vmap_area+0xd51/0x1490 mm/vmalloc.c:2092
 __get_vm_area_node+0x1f8/0x300 mm/vmalloc.c:3187
 __vmalloc_node_range_noprof+0x301/0x12f0 mm/vmalloc.c:3853
 __vmalloc_node_noprof mm/vmalloc.c:3956 [inline]
 __vmalloc_noprof+0xb1/0xf0 mm/vmalloc.c:3970
 xfs_buf_alloc_backing_mem fs/xfs/xfs_buf.c:239 [inline]
 xfs_buf_alloc+0xed3/0x1d40 fs/xfs/xfs_buf.c:312
 xfs_buf_find_insert+0xab/0x1470 fs/xfs/xfs_buf.c:505
 xfs_buf_get_map+0x1264/0x1860 fs/xfs/xfs_buf.c:609
 xfs_buf_read_map+0x82/0xa50 fs/xfs/xfs_buf.c:702
 xfs_buf_read fs/xfs/xfs_buf.h:259 [inline]
 xfs_attr_rmtval_get+0x5b3/0xba0 fs/xfs/libxfs/xfs_attr_remote.c:434
 xfs_attr_node_get+0x150/0x4f0 fs/xfs/libxfs/xfs_attr.c:1532
 xfs_attr_get_ilocked+0x330/0x410 fs/xfs/libxfs/xfs_attr.c:248
 xfs_attr_get+0x492/0x5e0 fs/xfs/libxfs/xfs_attr.c:289
 xfs_xattr_get+0x125/0x1c0 fs/xfs/xfs_xattr.c:150
 vfs_getxattr_alloc+0x52c/0x580 fs/xattr.c:404
 ima_read_xattr+0x38/0x60 security/integrity/ima/ima_appraise.c:230
 process_measurement+0xfd7/0x1a40 security/integrity/ima/ima_main.c:386
 ima_file_check+0xd7/0x120 security/integrity/ima/ima_main.c:633
 security_file_post_open+0xbb/0x290 security/security.c:3160
 do_open fs/namei.c:3889 [inline]
 path_openat+0x2f26/0x3830 fs/namei.c:4046
 do_filp_open+0x1fa/0x410 fs/namei.c:4073
 do_sys_openat2+0x121/0x1c0 fs/open.c:1435
 do_sys_open fs/open.c:1450 [inline]
 __do_sys_openat fs/open.c:1466 [inline]
 __se_sys_openat fs/open.c:1461 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1461
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f45d818ebe9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f45d90c6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f45d83c6090 RCX: 00007f45d818ebe9
RDX: 0000000000000042 RSI: 0000200000000000 RDI: ffffffffffffff9c
RBP: 00007f45d8211e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f45d83c6128 R14: 00007f45d83c6090 R15: 00007ffcbd1f5358
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/01 06:17 upstream 5c3b3264e585 807a3b61 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in xfs_ilock_attr_map_shared
2025/09/01 06:17 upstream 5c3b3264e585 807a3b61 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in xfs_ilock_attr_map_shared
2025/07/09 06:11 upstream 733923397fd9 f4e5e155 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in xfs_ilock_attr_map_shared
* Struck through repros no longer work on HEAD.