syzbot


possible deadlock in page_cache_ra_unbounded

Status: upstream: reported on 2025/07/16 14:50
Reported-by: syzbot+9d15437a92fbe990f551@syzkaller.appspotmail.com
First crash: 4d00h, last: 3d12h
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in page_cache_ra_unbounded mm fs 4 C error done 163 181d 942d 28/29 fixed on 2025/03/05 08:48
upstream possible deadlock in page_cache_ra_unbounded (2) fs mm 4 3 18d 93d 0/29 moderation: reported on 2025/04/17 16:05

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.1.145-syzkaller #0 Not tainted
------------------------------------------------------
syz.0.2221/13803 is trying to acquire lock:
ffff888054f9ec80 (mapping.invalidate_lock#12){++++}-{3:3}, at: filemap_invalidate_lock_shared include/linux/fs.h:813 [inline]
ffff888054f9ec80 (mapping.invalidate_lock#12){++++}-{3:3}, at: page_cache_ra_unbounded+0xd8/0x770 mm/readahead.c:226

but task is already holding lock:
ffff888054f9e840 (&ni->ni_lock/5){+.+.}-{3:3}, at: ni_lock fs/ntfs3/ntfs_fs.h:1102 [inline]
ffff888054f9e840 (&ni->ni_lock/5){+.+.}-{3:3}, at: ntfs_fiemap+0xc4/0x130 fs/ntfs3/file.c:1168

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&ni->ni_lock/5){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x120/0xaf0 kernel/locking/mutex.c:747
       ni_lock fs/ntfs3/ntfs_fs.h:1102 [inline]
       ntfs_fallocate+0x4c7/0xf20 fs/ntfs3/file.c:518
       vfs_fallocate+0x584/0x6f0 fs/open.c:323
       ioctl_preallocate fs/ioctl.c:290 [inline]
       file_ioctl fs/ioctl.c:-1 [inline]
       do_vfs_ioctl+0x1a9d/0x1d10 fs/ioctl.c:849
       __do_sys_ioctl fs/ioctl.c:868 [inline]
       __se_sys_ioctl+0x83/0x170 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (mapping.invalidate_lock#12){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain kernel/locking/lockdep.c:3825 [inline]
       __lock_acquire+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049
       lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
       down_read+0x42/0x2d0 kernel/locking/rwsem.c:1520
       filemap_invalidate_lock_shared include/linux/fs.h:813 [inline]
       page_cache_ra_unbounded+0xd8/0x770 mm/readahead.c:226
       do_sync_mmap_readahead+0x5ea/0x780 mm/filemap.c:3136
       filemap_fault+0x6d7/0x1670 mm/filemap.c:3228
       __do_fault+0x13b/0x4e0 mm/memory.c:4280
       do_shared_fault mm/memory.c:4686 [inline]
       do_fault mm/memory.c:4764 [inline]
       handle_pte_fault mm/memory.c:5031 [inline]
       __handle_mm_fault mm/memory.c:5173 [inline]
       handle_mm_fault+0x1a93/0x3e70 mm/memory.c:5294
       do_user_addr_fault+0x51f/0xb10 arch/x86/mm/fault.c:1340
       handle_page_fault arch/x86/mm/fault.c:1431 [inline]
       exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1487
       asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608
       copy_user_enhanced_fast_string+0xa/0x40 arch/x86/lib/copy_user_64.S:165
       copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline]
       raw_copy_to_user arch/x86/include/asm/uaccess_64.h:58 [inline]
       _copy_to_user+0xea/0x130 lib/usercopy.c:41
       copy_to_user include/linux/uaccess.h:169 [inline]
       ni_fiemap+0x4ec/0x1300 fs/ntfs3/frecord.c:2140
       ntfs_fiemap+0xd7/0x130 fs/ntfs3/file.c:1170
       ioctl_fiemap fs/ioctl.c:219 [inline]
       do_vfs_ioctl+0x1425/0x1d10 fs/ioctl.c:810
       __do_sys_ioctl fs/ioctl.c:868 [inline]
       __se_sys_ioctl+0x83/0x170 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ni->ni_lock/5);
                               lock(mapping.invalidate_lock#12);
                               lock(&ni->ni_lock/5);
  lock(mapping.invalidate_lock#12);

 *** DEADLOCK ***

1 lock held by syz.0.2221/13803:
 #0: ffff888054f9e840 (&ni->ni_lock/5){+.+.}-{3:3}, at: ni_lock fs/ntfs3/ntfs_fs.h:1102 [inline]
 #0: ffff888054f9e840 (&ni->ni_lock/5){+.+.}-{3:3}, at: ntfs_fiemap+0xc4/0x130 fs/ntfs3/file.c:1168

stack backtrace:
CPU: 0 PID: 13803 Comm: syz.0.2221 Not tainted 6.1.145-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 check_noncircular+0x274/0x310 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain kernel/locking/lockdep.c:3825 [inline]
 __lock_acquire+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049
 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
 down_read+0x42/0x2d0 kernel/locking/rwsem.c:1520
 filemap_invalidate_lock_shared include/linux/fs.h:813 [inline]
 page_cache_ra_unbounded+0xd8/0x770 mm/readahead.c:226
 do_sync_mmap_readahead+0x5ea/0x780 mm/filemap.c:3136
 filemap_fault+0x6d7/0x1670 mm/filemap.c:3228
 __do_fault+0x13b/0x4e0 mm/memory.c:4280
 do_shared_fault mm/memory.c:4686 [inline]
 do_fault mm/memory.c:4764 [inline]
 handle_pte_fault mm/memory.c:5031 [inline]
 __handle_mm_fault mm/memory.c:5173 [inline]
 handle_mm_fault+0x1a93/0x3e70 mm/memory.c:5294
 do_user_addr_fault+0x51f/0xb10 arch/x86/mm/fault.c:1340
 handle_page_fault arch/x86/mm/fault.c:1431 [inline]
 exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1487
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0010:copy_user_enhanced_fast_string+0xa/0x40 arch/x86/lib/copy_user_64.S:166
Code: ff c9 75 f2 89 d1 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 31 c0 0f 01 ca c3 8d 0c ca 89 ca eb 20 0f 01 cb 83 fa 40 72 38 89 d1 <f3> a4 31 c0 0f 01 ca c3 89 ca eb 0a 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc90003667828 EFLAGS: 00050202
RAX: ffffffff8407df01 RBX: 00000000000034f0 RCX: 0000000000002890
RDX: 00000000000034f0 RSI: ffff888061b28c60 RDI: 0000200000001000
RBP: 0000000000000000 R08: dffffc0000000000 R09: ffffed100c36569e
R10: 0000000000000000 R11: 0000000000000698 R12: 00007fffffffbb10
R13: ffff888054f9e880 R14: 00002000000003a0 R15: ffff888061b28000
 copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline]
 raw_copy_to_user arch/x86/include/asm/uaccess_64.h:58 [inline]
 _copy_to_user+0xea/0x130 lib/usercopy.c:41
 copy_to_user include/linux/uaccess.h:169 [inline]
 ni_fiemap+0x4ec/0x1300 fs/ntfs3/frecord.c:2140
 ntfs_fiemap+0xd7/0x130 fs/ntfs3/file.c:1170
 ioctl_fiemap fs/ioctl.c:219 [inline]
 do_vfs_ioctl+0x1425/0x1d10 fs/ioctl.c:810
 __do_sys_ioctl fs/ioctl.c:868 [inline]
 __se_sys_ioctl+0x83/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fd0b238e929
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:00007fd0b319f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fd0b25b5fa0 RCX: 00007fd0b238e929
RDX: 0000200000000380 RSI: 00000000c020660b RDI: 0000000000000004
RBP: 00007fd0b2410ca1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fd0b25b5fa0 R15: 00007ffe211ba5e8
 </TASK>
----------------
Code disassembly (best guess):
   0:	ff c9                	dec    %ecx
   2:	75 f2                	jne    0xfffffff6
   4:	89 d1                	mov    %edx,%ecx
   6:	c1 e9 03             	shr    $0x3,%ecx
   9:	83 e2 07             	and    $0x7,%edx
   c:	f3 48 a5             	rep movsq %ds:(%rsi),%es:(%rdi)
   f:	89 d1                	mov    %edx,%ecx
  11:	f3 a4                	rep movsb %ds:(%rsi),%es:(%rdi)
  13:	31 c0                	xor    %eax,%eax
  15:	0f 01 ca             	clac
  18:	c3                   	ret
  19:	8d 0c ca             	lea    (%rdx,%rcx,8),%ecx
  1c:	89 ca                	mov    %ecx,%edx
  1e:	eb 20                	jmp    0x40
  20:	0f 01 cb             	stac
  23:	83 fa 40             	cmp    $0x40,%edx
  26:	72 38                	jb     0x60
  28:	89 d1                	mov    %edx,%ecx
* 2a:	f3 a4                	rep movsb %ds:(%rsi),%es:(%rdi) <-- trapping instruction
  2c:	31 c0                	xor    %eax,%eax
  2e:	0f 01 ca             	clac
  31:	c3                   	ret
  32:	89 ca                	mov    %ecx,%edx
  34:	eb 0a                	jmp    0x40
  36:	90                   	nop
  37:	90                   	nop
  38:	90                   	nop
  39:	90                   	nop
  3a:	90                   	nop
  3b:	90                   	nop
  3c:	90                   	nop
  3d:	90                   	nop
  3e:	90                   	nop
  3f:	90                   	nop

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/17 02:51 linux-6.1.y f2198ea7eb3e 44f8051e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in page_cache_ra_unbounded
2025/07/17 02:51 linux-6.1.y f2198ea7eb3e 44f8051e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in page_cache_ra_unbounded
2025/07/16 15:00 linux-6.1.y f2198ea7eb3e 124ec9cc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in page_cache_ra_unbounded
2025/07/16 14:49 linux-6.1.y f2198ea7eb3e 124ec9cc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in page_cache_ra_unbounded
* Struck through repros no longer work on HEAD.