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Message-ID: <69032927.050a0220.32483.022a.GAE@google.com>
Date: Thu, 30 Oct 2025 02:00:23 -0700
From: syzbot <syzbot+d7230f03206380ea0908@...kaller.appspotmail.com>
To: akpm@...ux-foundation.org, clm@...com, dsterba@...e.com,
josef@...icpanda.com, linux-btrfs@...r.kernel.org,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, syzkaller-bugs@...glegroups.com, willy@...radead.org
Subject: [syzbot] [btrfs] possible deadlock in page_cache_ra_unbounded (3)
Hello,
syzbot found the following issue on:
HEAD commit: 72761a7e3122 Merge tag 'driver-core-6.18-rc3' of git://git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=123dee7c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=8345ce4ce316ca28
dashboard link: https://syzkaller.appspot.com/bug?extid=d7230f03206380ea0908
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/733feb854771/disk-72761a7e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/94891a491db1/vmlinux-72761a7e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1dc1e26ee843/bzImage-72761a7e.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d7230f03206380ea0908@...kaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.7.719/14515 is trying to acquire lock:
ffff88805d893bd8 (mapping.invalidate_lock#3){.+.+}-{4:4}, at: filemap_invalidate_lock_shared include/linux/fs.h:1045 [inline]
ffff88805d893bd8 (mapping.invalidate_lock#3){.+.+}-{4:4}, at: page_cache_ra_unbounded+0x1a3/0x8e0 mm/readahead.c:233
but task is already holding lock:
ffff88813ff74238 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x267/0x870 fs/kernfs/dir.c:1893
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #5 (&root->kernfs_rwsem){++++}-{4:4}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
down_write+0x3a/0x50 kernel/locking/rwsem.c:1590
kernfs_add_one+0x41/0x520 fs/kernfs/dir.c:791
kernfs_create_dir_ns+0xde/0x130 fs/kernfs/dir.c:1093
sysfs_create_dir_ns+0x123/0x280 fs/sysfs/dir.c:59
create_dir lib/kobject.c:73 [inline]
kobject_add_internal+0x5a5/0xb50 lib/kobject.c:240
kobject_add_varg lib/kobject.c:374 [inline]
kobject_init_and_add+0x125/0x190 lib/kobject.c:457
btrfs_sysfs_add_qgroups+0x111/0x2b0 fs/btrfs/sysfs.c:2645
btrfs_quota_enable+0x25d/0x2920 fs/btrfs/qgroup.c:1022
btrfs_ioctl_quota_ctl+0x186/0x1c0 fs/btrfs/ioctl.c:3667
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xff/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #4 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
__mutex_lock_common kernel/locking/rtmutex_api.c:535 [inline]
mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:547
btrfs_quota_enable+0x29c/0x2920 fs/btrfs/qgroup.c:1051
btrfs_ioctl_quota_ctl+0x186/0x1c0 fs/btrfs/ioctl.c:3667
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xff/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #3 (btrfs_trans_num_extwriters){++++}-{0:0}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
join_transaction+0x1a4/0xca0 fs/btrfs/transaction.c:321
start_transaction+0x6b6/0x1620 fs/btrfs/transaction.c:705
btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6270
inode_update_time fs/inode.c:2117 [inline]
touch_atime+0x2f9/0x6d0 fs/inode.c:2190
file_accessed include/linux/fs.h:2673 [inline]
filemap_read+0x100b/0x11a0 mm/filemap.c:2820
__kernel_read+0x4d8/0x970 fs/read_write.c:530
integrity_kernel_read+0x89/0xd0 security/integrity/iint.c:28
ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:480 [inline]
ima_calc_file_shash security/integrity/ima/ima_crypto.c:511 [inline]
ima_calc_file_hash+0x86a/0x1700 security/integrity/ima/ima_crypto.c:568
ima_collect_measurement+0x42e/0x900 security/integrity/ima/ima_api.c:293
process_measurement+0x112d/0x1a40 security/integrity/ima/ima_main.c:405
ima_file_check+0xd7/0x120 security/integrity/ima/ima_main.c:633
security_file_post_open+0xbb/0x290 security/security.c:3199
do_open fs/namei.c:3977 [inline]
path_openat+0x2f32/0x3840 fs/namei.c:4134
do_filp_open+0x1fa/0x410 fs/namei.c:4161
do_sys_openat2+0x121/0x1c0 fs/open.c:1437
do_sys_open fs/open.c:1452 [inline]
__do_sys_openat fs/open.c:1468 [inline]
__se_sys_openat fs/open.c:1463 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1463
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #2 (btrfs_trans_num_writers){++++}-{0:0}:
reacquire_held_locks+0x127/0x1d0 kernel/locking/lockdep.c:5385
__lock_release kernel/locking/lockdep.c:5574 [inline]
lock_release+0x1b4/0x3e0 kernel/locking/lockdep.c:5889
percpu_up_read include/linux/percpu-rwsem.h:112 [inline]
__sb_end_write include/linux/fs.h:1911 [inline]
sb_end_intwrite+0x26/0x1c0 include/linux/fs.h:2028
__btrfs_end_transaction+0x248/0x640 fs/btrfs/transaction.c:1076
btrfs_finish_one_ordered+0x139a/0x21a0 fs/btrfs/inode.c:3236
btrfs_work_helper+0x39b/0xc00 fs/btrfs/async-thread.c:312
process_one_work kernel/workqueue.c:3263 [inline]
process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #1 (btrfs_ordered_extent){++++}-{0:0}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
btrfs_start_ordered_extent_nowriteback+0x39c/0x6e0 fs/btrfs/ordered-data.c:896
lock_extents_for_read+0x151/0xb50 fs/btrfs/extent_io.c:1314
btrfs_readahead+0x183/0x730 fs/btrfs/extent_io.c:2686
read_pages+0x17a/0x580 mm/readahead.c:163
page_cache_ra_unbounded+0x699/0x8e0 mm/readahead.c:302
page_cache_sync_readahead include/linux/pagemap.h:1379 [inline]
defrag_one_cluster fs/btrfs/defrag.c:1313 [inline]
btrfs_defrag_file+0xa02/0x2eb0 fs/btrfs/defrag.c:1455
btrfs_ioctl_defrag+0x389/0x490 fs/btrfs/ioctl.c:2572
btrfs_ioctl+0xbe2/0xd00 fs/btrfs/ioctl.c:-1
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xff/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #0 (mapping.invalidate_lock#3){.+.+}-{4:4}:
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
down_read+0x97/0x1f0 kernel/locking/rwsem.c:1537
filemap_invalidate_lock_shared include/linux/fs.h:1045 [inline]
page_cache_ra_unbounded+0x1a3/0x8e0 mm/readahead.c:233
do_sync_mmap_readahead+0x554/0x670 mm/filemap.c:3340
filemap_fault+0x6c2/0x12c0 mm/filemap.c:3489
__do_fault+0x138/0x390 mm/memory.c:5280
do_shared_fault mm/memory.c:5762 [inline]
do_fault mm/memory.c:5836 [inline]
do_pte_missing mm/memory.c:4361 [inline]
handle_pte_fault mm/memory.c:6177 [inline]
__handle_mm_fault mm/memory.c:6318 [inline]
handle_mm_fault+0x117f/0x3400 mm/memory.c:6487
do_user_addr_fault+0x764/0x1380 arch/x86/mm/fault.c:1387
handle_page_fault arch/x86/mm/fault.c:1476 [inline]
exc_page_fault+0x82/0x100 arch/x86/mm/fault.c:1532
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
filldir+0x2b6/0x6c0 fs/readdir.c:295
dir_emit include/linux/fs.h:3986 [inline]
kernfs_fop_readdir+0x53a/0x870 fs/kernfs/dir.c:1910
iterate_dir+0x3a5/0x580 fs/readdir.c:108
__do_sys_getdents fs/readdir.c:326 [inline]
__se_sys_getdents+0xe4/0x250 fs/readdir.c:312
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
other info that might help us debug this:
Chain exists of:
mapping.invalidate_lock#3 --> &fs_info->qgroup_ioctl_lock --> &root->kernfs_rwsem
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
rlock(&root->kernfs_rwsem);
lock(&fs_info->qgroup_ioctl_lock);
lock(&root->kernfs_rwsem);
rlock(mapping.invalidate_lock#3);
*** DEADLOCK ***
3 locks held by syz.7.719/14515:
#0: ffff888050799528 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x253/0x320 fs/file.c:1232
#1: ffff88806622d3f8 (&type->i_mutex_dir_key#4){++++}-{4:4}, at: iterate_dir+0x29e/0x580 fs/readdir.c:101
#2: ffff88813ff74238 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x267/0x870 fs/kernfs/dir.c:1893
stack backtrace:
CPU: 1 UID: 0 PID: 14515 Comm: syz.7.719 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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
down_read+0x97/0x1f0 kernel/locking/rwsem.c:1537
filemap_invalidate_lock_shared include/linux/fs.h:1045 [inline]
page_cache_ra_unbounded+0x1a3/0x8e0 mm/readahead.c:233
do_sync_mmap_readahead+0x554/0x670 mm/filemap.c:3340
filemap_fault+0x6c2/0x12c0 mm/filemap.c:3489
__do_fault+0x138/0x390 mm/memory.c:5280
do_shared_fault mm/memory.c:5762 [inline]
do_fault mm/memory.c:5836 [inline]
do_pte_missing mm/memory.c:4361 [inline]
handle_pte_fault mm/memory.c:6177 [inline]
__handle_mm_fault mm/memory.c:6318 [inline]
handle_mm_fault+0x117f/0x3400 mm/memory.c:6487
do_user_addr_fault+0x764/0x1380 arch/x86/mm/fault.c:1387
handle_page_fault arch/x86/mm/fault.c:1476 [inline]
exc_page_fault+0x82/0x100 arch/x86/mm/fault.c:1532
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0010:filldir+0x2b6/0x6c0 fs/readdir.c:296
Code: 87 73 02 00 00 0f 01 cb 0f ae e8 48 8b 44 24 50 49 89 44 24 08 48 8b 4c 24 08 48 8b 44 24 58 48 89 01 48 8b 04 24 8b 54 24 1c <66> 89 41 10 80 e2 0f 41 89 c7 42 88 54 39 ff 49 63 ee c6 44 29 12
RSP: 0018:ffffc9001aed7c58 EFLAGS: 00050283
RAX: 0000000000000020 RBX: ffffc9001aed7e38 RCX: 0000200000001ff0
RDX: 0000000000000004 RSI: 0000200000001fd8 RDI: 0000200000002010
RBP: 00007ffffffff000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed100a568001 R12: 0000200000001fd8
R13: ffffffff8aea35e0 R14: 0000000000000006 R15: 0000200000002010
dir_emit include/linux/fs.h:3986 [inline]
kernfs_fop_readdir+0x53a/0x870 fs/kernfs/dir.c:1910
iterate_dir+0x3a5/0x580 fs/readdir.c:108
__do_sys_getdents fs/readdir.c:326 [inline]
__se_sys_getdents+0xe4/0x250 fs/readdir.c:312
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f45faaaefc9
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:00007f45f08cc038 EFLAGS: 00000246 ORIG_RAX: 000000000000004e
RAX: ffffffffffffffda RBX: 00007f45fad06180 RCX: 00007f45faaaefc9
RDX: 0000000000000117 RSI: 0000200000001fc0 RDI: 000000000000000c
RBP: 00007f45fab31f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f45fad06218 R14: 00007f45fad06180 R15: 00007ffe1c9c7da8
</TASK>
----------------
Code disassembly (best guess):
0: 87 73 02 xchg %esi,0x2(%rbx)
3: 00 00 add %al,(%rax)
5: 0f 01 cb stac
8: 0f ae e8 lfence
b: 48 8b 44 24 50 mov 0x50(%rsp),%rax
10: 49 89 44 24 08 mov %rax,0x8(%r12)
15: 48 8b 4c 24 08 mov 0x8(%rsp),%rcx
1a: 48 8b 44 24 58 mov 0x58(%rsp),%rax
1f: 48 89 01 mov %rax,(%rcx)
22: 48 8b 04 24 mov (%rsp),%rax
26: 8b 54 24 1c mov 0x1c(%rsp),%edx
* 2a: 66 89 41 10 mov %ax,0x10(%rcx) <-- trapping instruction
2e: 80 e2 0f and $0xf,%dl
31: 41 89 c7 mov %eax,%r15d
34: 42 88 54 39 ff mov %dl,-0x1(%rcx,%r15,1)
39: 49 63 ee movslq %r14d,%rbp
3c: c6 .byte 0xc6
3d: 44 29 12 sub %r10d,(%rdx)
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@...glegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
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