syzbot


possible deadlock in page_cache_ra_order

Status: upstream: reported on 2026/05/31 02:05
Subsystems: mm fs
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+8bd419f88e25ab12cb75@syzkaller.appspotmail.com
First crash: 53d, last: 1d04h
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
6842e9d3-4123-4558-b23c-857df07c7b24 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ✅ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ possible deadlock in page_cache_ra_order 2026/05/29 22:51 2026/05/29 22:51 2026/05/29 23:47 6b4a844333e83556da95d61d7f207e7ef5cd4bc6

			
		
Discussions (2)
Title Replies (including bot) Last reply
[syzbot] Monthly fs report (Jul 2026) 0 (1) 2026/07/10 20:32
[syzbot] [mm?] [fs?] possible deadlock in page_cache_ra_order 0 (1) 2026/05/31 02:05

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.2.158/6792 is trying to acquire lock:
ffff888060646098 (mapping.invalidate_lock#6){++++}-{4:4}, at: filemap_invalidate_lock_shared include/linux/fs.h:1089 [inline]
ffff888060646098 (mapping.invalidate_lock#6){++++}-{4:4}, at: do_page_cache_ra mm/readahead.c:347 [inline]
ffff888060646098 (mapping.invalidate_lock#6){++++}-{4:4}, at: page_cache_ra_order+0x2b1/0x4a0 mm/readahead.c:558

but task is already holding lock:
ffff888062752e80 (&ni->ni_lock#2/5){+.+.}-{4:4}, at: ni_lock fs/ntfs3/ntfs_fs.h:1222 [inline]
ffff888062752e80 (&ni->ni_lock#2/5){+.+.}-{4:4}, at: ntfs_readdir+0x752/0xec0 fs/ntfs3/dir.c:499

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&ni->ni_lock#2/5){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline]
       mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578
       ni_lock fs/ntfs3/ntfs_fs.h:1222 [inline]
       ntfs_fallocate+0x914/0xf70 fs/ntfs3/file.c:617
       vfs_fallocate+0x663/0x7f0 fs/open.c:338
       ksys_fallocate fs/open.c:362 [inline]
       __do_sys_fallocate fs/open.c:367 [inline]
       __se_sys_fallocate fs/open.c:365 [inline]
       __x64_sys_fallocate+0xbf/0x110 fs/open.c:365
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (mapping.invalidate_lock#6){++++}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x1520/0x2ce0 kernel/locking/lockdep.c:5237
       lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
       down_read+0x97/0x200 kernel/locking/rwsem.c:1574
       filemap_invalidate_lock_shared include/linux/fs.h:1089 [inline]
       do_page_cache_ra mm/readahead.c:347 [inline]
       page_cache_ra_order+0x2b1/0x4a0 mm/readahead.c:558
       do_sync_mmap_readahead+0x4d6/0x7c0 mm/filemap.c:3428
       filemap_fault+0x7e2/0x13c0 mm/filemap.c:3582
       __do_fault+0x138/0x2a0 mm/memory.c:5425
       do_shared_fault mm/memory.c:5924 [inline]
       do_fault mm/memory.c:5998 [inline]
       do_pte_missing+0x659/0x28f0 mm/memory.c:4566
       handle_pte_fault mm/memory.c:6379 [inline]
       __handle_mm_fault mm/memory.c:6517 [inline]
       handle_mm_fault+0xd28/0x13f0 mm/memory.c:6686
       do_user_addr_fault+0x744/0x1340 arch/x86/mm/fault.c:1394
       handle_page_fault arch/x86/mm/fault.c:1483 [inline]
       exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1536
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
       stac arch/x86/include/asm/smap.h:-1 [inline]
       filldir+0x29f/0x630 fs/readdir.c:286
       dir_emit include/linux/fs.h:3587 [inline]
       ntfs_dir_emit fs/ntfs3/dir.c:346 [inline]
       ntfs_read_hdr+0x8a4/0xc10 fs/ntfs3/dir.c:387
       ntfs_readdir+0x9ea/0xec0 fs/ntfs3/dir.c:547
       iterate_dir+0x2f1/0x4e0 fs/readdir.c:110
       __do_sys_getdents fs/readdir.c:319 [inline]
       __se_sys_getdents+0xf1/0x270 fs/readdir.c:304
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x174/0x580 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
       ----                    ----
  lock(&ni->ni_lock#2/5);
                               lock(mapping.invalidate_lock#6);
                               lock(&ni->ni_lock#2/5);
  rlock(mapping.invalidate_lock#6);

 *** DEADLOCK ***

3 locks held by syz.2.158/6792:
 #0: ffff888032fcab28 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1259
 #1: ffff888062753138 (&type->i_mutex_dir_key#8){++++}-{4:4}, at: iterate_dir+0x215/0x4e0 fs/readdir.c:103
 #2: ffff888062752e80 (&ni->ni_lock#2/5){+.+.}-{4:4}, at: ni_lock fs/ntfs3/ntfs_fs.h:1222 [inline]
 #2: ffff888062752e80 (&ni->ni_lock#2/5){+.+.}-{4:4}, at: ntfs_readdir+0x752/0xec0 fs/ntfs3/dir.c:499

stack backtrace:
CPU: 1 UID: 0 PID: 6792 Comm: syz.2.158 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043
 check_noncircular+0x12e/0x150 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 kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x1520/0x2ce0 kernel/locking/lockdep.c:5237
 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
 down_read+0x97/0x200 kernel/locking/rwsem.c:1574
 filemap_invalidate_lock_shared include/linux/fs.h:1089 [inline]
 do_page_cache_ra mm/readahead.c:347 [inline]
 page_cache_ra_order+0x2b1/0x4a0 mm/readahead.c:558
 do_sync_mmap_readahead+0x4d6/0x7c0 mm/filemap.c:3428
 filemap_fault+0x7e2/0x13c0 mm/filemap.c:3582
 __do_fault+0x138/0x2a0 mm/memory.c:5425
 do_shared_fault mm/memory.c:5924 [inline]
 do_fault mm/memory.c:5998 [inline]
 do_pte_missing+0x659/0x28f0 mm/memory.c:4566
 handle_pte_fault mm/memory.c:6379 [inline]
 __handle_mm_fault mm/memory.c:6517 [inline]
 handle_mm_fault+0xd28/0x13f0 mm/memory.c:6686
 do_user_addr_fault+0x744/0x1340 arch/x86/mm/fault.c:1394
 handle_page_fault arch/x86/mm/fault.c:1483 [inline]
 exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1536
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
RIP: 0010:filldir+0x29f/0x630 fs/readdir.c:288
Code: df 49 29 ef 48 b8 00 f0 ff ff ff 7f 00 00 49 39 c7 4c 0f 47 f8 bf 07 00 00 00 44 89 f6 e8 39 9d 82 ff 0f 01 cb 48 8b 44 24 20 <49> 89 47 08 48 bd 00 00 00 00 00 fc ff df 48 8b 44 24 40 48 89 03
RSP: 0018:ffffc90004fbfab0 EFLAGS: 00050297
RAX: 0000000000000920 RBX: 0000200000002010 RCX: ffff8880256c8000
RDX: 0000000000000002 RSI: 0000000000000009 RDI: 0000000000000007
RBP: 0000000000000020 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1004ad9001 R12: ffff88803a674000
R13: 0000000000000009 R14: 0000000000000009 R15: 0000200000001ff0
 dir_emit include/linux/fs.h:3587 [inline]
 ntfs_dir_emit fs/ntfs3/dir.c:346 [inline]
 ntfs_read_hdr+0x8a4/0xc10 fs/ntfs3/dir.c:387
 ntfs_readdir+0x9ea/0xec0 fs/ntfs3/dir.c:547
 iterate_dir+0x2f1/0x4e0 fs/readdir.c:110
 __do_sys_getdents fs/readdir.c:319 [inline]
 __se_sys_getdents+0xf1/0x270 fs/readdir.c:304
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3508c5de99
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3506e95028 EFLAGS: 00000246 ORIG_RAX: 000000000000004e
RAX: ffffffffffffffda RBX: 00007f3508ee6090 RCX: 00007f3508c5de99
RDX: 00000000000000b8 RSI: 0000200000001fc0 RDI: 0000000000000009
RBP: 00007f3508cf3eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3508ee6128 R14: 00007f3508ee6090 R15: 00007ffc10520a38
 </TASK>
ntfs3(loop2): failed to convert name for inode 1e.
ntfs3(loop2): ino=1f, mi_enum_attr
----------------
Code disassembly (best guess):
   0:	df 49 29             	fisttps 0x29(%rcx)
   3:	ef                   	out    %eax,(%dx)
   4:	48 b8 00 f0 ff ff ff 	movabs $0x7ffffffff000,%rax
   b:	7f 00 00
   e:	49 39 c7             	cmp    %rax,%r15
  11:	4c 0f 47 f8          	cmova  %rax,%r15
  15:	bf 07 00 00 00       	mov    $0x7,%edi
  1a:	44 89 f6             	mov    %r14d,%esi
  1d:	e8 39 9d 82 ff       	call   0xff829d5b
  22:	0f 01 cb             	stac
  25:	48 8b 44 24 20       	mov    0x20(%rsp),%rax
* 2a:	49 89 47 08          	mov    %rax,0x8(%r15) <-- trapping instruction
  2e:	48 bd 00 00 00 00 00 	movabs $0xdffffc0000000000,%rbp
  35:	fc ff df
  38:	48 8b 44 24 40       	mov    0x40(%rsp),%rax
  3d:	48 89 03             	mov    %rax,(%rbx)

Crashes (9):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/18 08:46 upstream 94515f3a7d42 72524a66 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in page_cache_ra_order
2026/07/12 14:14 upstream 44696aa3a489 d78ea535 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in page_cache_ra_order
2026/07/11 23:16 upstream dd3210c47e8d d78ea535 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in page_cache_ra_order
2026/07/04 06:46 upstream d2c9a99135da fcece630 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in page_cache_ra_order
2026/05/27 07:58 linux-next e7e28506af98 2b01f00e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in page_cache_ra_order
2026/05/27 07:55 linux-next e7e28506af98 2b01f00e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in page_cache_ra_order
2026/05/27 07:54 linux-next e7e28506af98 2b01f00e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in page_cache_ra_order
2026/05/27 07:54 linux-next e7e28506af98 2b01f00e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in page_cache_ra_order
2026/05/27 01:58 linux-next e7e28506af98 2b01f00e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in page_cache_ra_order
* Struck through repros no longer work on HEAD.