syzbot
possible deadlock in page_cache_ra_order
Status:
upstream: reported on 2026/05/31 02:05
Subsystems:
fs
mm
Labels:
prio:high
[Documentation on labels]
Reported-by: syzbot+8bd419f88e25ab12cb75@syzkaller.appspotmail.com
First crash: 77d, last: 10d
Sample crash report:
ntfs3(loop0): failed to convert "0080" to macinuit
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.864/12335 is trying to acquire lock:
ffff888062797760 (mapping.invalidate_lock#6){++++}-{4:4}, at: filemap_invalidate_lock_shared include/linux/fs.h:1089 [inline]
ffff888062797760 (mapping.invalidate_lock#6){++++}-{4:4}, at: do_page_cache_ra mm/readahead.c:347 [inline]
ffff888062797760 (mapping.invalidate_lock#6){++++}-{4:4}, at: page_cache_ra_order+0x2b1/0x4a0 mm/readahead.c:558
but task is already holding lock:
ffff8880627963a8 (&ni->ni_lock/5){+.+.}-{4:4}, at: ni_lock fs/ntfs3/ntfs_fs.h:1222 [inline]
ffff8880627963a8 (&ni->ni_lock/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/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+0x54d/0xf70 fs/ntfs3/file.c:535
vfs_fallocate+0x663/0x7f0 fs/open.c:338
ioctl_preallocate fs/ioctl.c:289 [inline]
file_ioctl+0x5db/0x7e0 fs/ioctl.c:332
do_vfs_ioctl+0xc2a/0x1550 fs/ioctl.c:576
__do_sys_ioctl fs/ioctl.c:595 [inline]
__se_sys_ioctl+0x82/0x170 fs/ioctl.c:583
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]
filldir64+0x29e/0x620 fs/readdir.c:365
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_getdents64 fs/readdir.c:399 [inline]
__se_sys_getdents64+0xf1/0x280 fs/readdir.c:384
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/5);
lock(mapping.invalidate_lock#6);
lock(&ni->ni_lock/5);
rlock(mapping.invalidate_lock#6);
*** DEADLOCK ***
3 locks held by syz.0.864/12335:
#0: ffff88803d5cb928 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1259
#1: ffff888062796660 (&type->i_mutex_dir_key#9){++++}-{4:4}, at: iterate_dir+0x215/0x4e0 fs/readdir.c:103
#2: ffff8880627963a8 (&ni->ni_lock/5){+.+.}-{4:4}, at: ni_lock fs/ntfs3/ntfs_fs.h:1222 [inline]
#2: ffff8880627963a8 (&ni->ni_lock/5){+.+.}-{4:4}, at: ntfs_readdir+0x752/0xec0 fs/ntfs3/dir.c:499
stack backtrace:
CPU: 0 UID: 0 PID: 12335 Comm: syz.0.864 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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:filldir64+0x29e/0x620 fs/readdir.c:367
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 7a 93 82 ff 0f 01 cb 48 8b 44 24 28 <49> 89 47 08 48 bd 00 00 00 00 00 fc ff df 48 8b 44 24 58 48 89 03
RSP: 0018:ffffc90004fe7ab0 EFLAGS: 00050297
RAX: 0000000000000e18 RBX: 0000200000001208 RCX: ffff8880332d3e00
RDX: 0000000000000002 RSI: 0000000000000005 RDI: 0000000000000007
RBP: 0000000000000020 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed100665a7c1 R12: ffff88803c2ec000
R13: 0000000000000005 R14: 0000000000000005 R15: 00002000000011e8
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_getdents64 fs/readdir.c:399 [inline]
__se_sys_getdents64+0xf1/0x280 fs/readdir.c:384
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: 0033:0x7f0aad91e019
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:00007f0aabb55028 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f0aadba6090 RCX: 00007f0aad91e019
RDX: 0000000000001000 RSI: 0000200000000f80 RDI: 0000000000000009
RBP: 00007f0aad9b500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0aadba6128 R14: 00007f0aadba6090 R15: 00007fff52635338
</TASK>
ntfs3(loop0): failed to convert name for inode 1e.
ntfs3(loop0): 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 7a 93 82 ff call 0xff82939c
22: 0f 01 cb stac
25: 48 8b 44 24 28 mov 0x28(%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 58 mov 0x58(%rsp),%rax
3d: 48 89 03 mov %rax,(%rbx)
Struck through repros no longer work on HEAD.