| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <681e0719.050a0220.a19a9.0133.GAE@google.com>
Date: Fri, 09 May 2025 06:46:01 -0700
From: syzbot <syzbot+81394db39b0e2ed2db06@...kaller.appspotmail.com>
To: eadavis@...com, linux-kernel@...r.kernel.org,
syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [nilfs?] possible deadlock in nilfs_segctor_construct
Hello,
syzbot has tested the proposed patch but the reproducer is still triggering an issue:
possible deadlock in nilfs_mdt_get_block
======================================================
WARNING: possible circular locking dependency detected
6.15.0-rc5-syzkaller-00136-g9c69f8884904-dirty #0 Not tainted
------------------------------------------------------
segctord/5927 is trying to acquire lock:
ffff88803ffcc610 (sb_internal#2){.+.+}-{0:0}, at: nilfs_mdt_create_block fs/nilfs2/mdt.c:80 [inline]
ffff88803ffcc610 (sb_internal#2){.+.+}-{0:0}, at: nilfs_mdt_get_block+0x193/0xab0 fs/nilfs2/mdt.c:258
but task is already holding lock:
ffff8880422660a0 (&nilfs_bmap_mdt_lock_key){++++}-{4:4}, at: nilfs_bmap_propagate+0x2f/0x130 fs/nilfs2/bmap.c:328
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&nilfs_bmap_mdt_lock_key){++++}-{4:4}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
down_read+0x46/0x2e0 kernel/locking/rwsem.c:1524
nilfs_bmap_lookup_at_level+0x92/0x3d0 fs/nilfs2/bmap.c:65
nilfs_bmap_lookup fs/nilfs2/bmap.h:182 [inline]
nilfs_mdt_submit_block+0x3a3/0x830 fs/nilfs2/mdt.c:144
nilfs_mdt_read_block+0x46/0x320 fs/nilfs2/mdt.c:178
nilfs_mdt_get_block+0x11f/0xab0 fs/nilfs2/mdt.c:254
nilfs_palloc_get_block+0x18d/0x2b0 fs/nilfs2/alloc.c:239
nilfs_palloc_get_desc_block fs/nilfs2/alloc.c:296 [inline]
nilfs_palloc_prepare_alloc_entry+0x3a3/0xf40 fs/nilfs2/alloc.c:607
nilfs_ifile_create_inode+0x111/0x2e0 fs/nilfs2/ifile.c:61
nilfs_new_inode+0x1ed/0x750 fs/nilfs2/inode.c:321
nilfs_create+0x100/0x2f0 fs/nilfs2/namei.c:98
lookup_open fs/namei.c:3701 [inline]
open_last_lookups fs/namei.c:3800 [inline]
path_openat+0x14f1/0x3830 fs/namei.c:4036
do_filp_open+0x1fa/0x410 fs/namei.c:4066
do_sys_openat2+0x121/0x1c0 fs/open.c:1429
do_sys_open fs/open.c:1444 [inline]
__do_sys_openat fs/open.c:1460 [inline]
__se_sys_openat fs/open.c:1455 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1455
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #1 (&nilfs->ns_segctor_sem){++++}-{4:4}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
down_read+0x46/0x2e0 kernel/locking/rwsem.c:1524
nilfs_transaction_begin+0x365/0x710 fs/nilfs2/segment.c:221
nilfs_create+0xc9/0x2f0 fs/nilfs2/namei.c:95
lookup_open fs/namei.c:3701 [inline]
open_last_lookups fs/namei.c:3800 [inline]
path_openat+0x14f1/0x3830 fs/namei.c:4036
do_filp_open+0x1fa/0x410 fs/namei.c:4066
do_sys_openat2+0x121/0x1c0 fs/open.c:1429
do_sys_open fs/open.c:1444 [inline]
__do_sys_openat fs/open.c:1460 [inline]
__se_sys_openat fs/open.c:1455 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1455
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #0 (sb_internal#2){.+.+}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3166 [inline]
check_prevs_add kernel/locking/lockdep.c:3285 [inline]
validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3909
__lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
percpu_down_read include/linux/percpu-rwsem.h:52 [inline]
__sb_start_write include/linux/fs.h:1783 [inline]
sb_start_intwrite include/linux/fs.h:1966 [inline]
nilfs_transaction_begin+0x268/0x710 fs/nilfs2/segment.c:218
nilfs_mdt_create_block fs/nilfs2/mdt.c:80 [inline]
nilfs_mdt_get_block+0x193/0xab0 fs/nilfs2/mdt.c:258
nilfs_palloc_get_block+0x18d/0x2b0 fs/nilfs2/alloc.c:239
nilfs_palloc_get_entry_block+0x8c/0xa0 fs/nilfs2/alloc.c:355
nilfs_dat_prepare_entry fs/nilfs2/dat.c:45 [inline]
nilfs_dat_prepare_alloc fs/nilfs2/dat.c:82 [inline]
nilfs_dat_prepare_update+0xb1/0x300 fs/nilfs2/dat.c:250
nilfs_direct_propagate+0x1ac/0x370 fs/nilfs2/direct.c:279
nilfs_bmap_propagate+0x77/0x130 fs/nilfs2/bmap.c:329
nilfs_collect_file_data+0x4f/0xd0 fs/nilfs2/segment.c:589
nilfs_segctor_apply_buffers+0x161/0x330 fs/nilfs2/segment.c:1010
nilfs_segctor_scan_file+0x68e/0x8e0 fs/nilfs2/segment.c:1059
nilfs_segctor_collect_blocks fs/nilfs2/segment.c:1267 [inline]
nilfs_segctor_collect fs/nilfs2/segment.c:1547 [inline]
nilfs_segctor_do_construct+0x1eac/0x6970 fs/nilfs2/segment.c:2122
nilfs_segctor_construct+0x17b/0x690 fs/nilfs2/segment.c:2478
nilfs_segctor_thread_construct fs/nilfs2/segment.c:2585 [inline]
nilfs_segctor_thread+0x6cd/0xe00 fs/nilfs2/segment.c:2700
kthread+0x70e/0x8a0 kernel/kthread.c:464
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
other info that might help us debug this:
Chain exists of:
sb_internal#2 --> &nilfs->ns_segctor_sem --> &nilfs_bmap_mdt_lock_key
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&nilfs_bmap_mdt_lock_key);
lock(&nilfs->ns_segctor_sem);
lock(&nilfs_bmap_mdt_lock_key);
rlock(sb_internal#2);
*** DEADLOCK ***
1 lock held by segctord/5927:
#0: ffff8880422660a0 (&nilfs_bmap_mdt_lock_key){++++}-{4:4}, at: nilfs_bmap_propagate+0x2f/0x130 fs/nilfs2/bmap.c:328
stack backtrace:
CPU: 0 UID: 0 PID: 5927 Comm: segctord Not tainted 6.15.0-rc5-syzkaller-00136-g9c69f8884904-dirty #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:2079
check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2211
check_prev_add kernel/locking/lockdep.c:3166 [inline]
check_prevs_add kernel/locking/lockdep.c:3285 [inline]
validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3909
__lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
percpu_down_read include/linux/percpu-rwsem.h:52 [inline]
__sb_start_write include/linux/fs.h:1783 [inline]
sb_start_intwrite include/linux/fs.h:1966 [inline]
nilfs_transaction_begin+0x268/0x710 fs/nilfs2/segment.c:218
nilfs_mdt_create_block fs/nilfs2/mdt.c:80 [inline]
nilfs_mdt_get_block+0x193/0xab0 fs/nilfs2/mdt.c:258
nilfs_palloc_get_block+0x18d/0x2b0 fs/nilfs2/alloc.c:239
nilfs_palloc_get_entry_block+0x8c/0xa0 fs/nilfs2/alloc.c:355
nilfs_dat_prepare_entry fs/nilfs2/dat.c:45 [inline]
nilfs_dat_prepare_alloc fs/nilfs2/dat.c:82 [inline]
nilfs_dat_prepare_update+0xb1/0x300 fs/nilfs2/dat.c:250
nilfs_direct_propagate+0x1ac/0x370 fs/nilfs2/direct.c:279
nilfs_bmap_propagate+0x77/0x130 fs/nilfs2/bmap.c:329
nilfs_collect_file_data+0x4f/0xd0 fs/nilfs2/segment.c:589
nilfs_segctor_apply_buffers+0x161/0x330 fs/nilfs2/segment.c:1010
nilfs_segctor_scan_file+0x68e/0x8e0 fs/nilfs2/segment.c:1059
nilfs_segctor_collect_blocks fs/nilfs2/segment.c:1267 [inline]
nilfs_segctor_collect fs/nilfs2/segment.c:1547 [inline]
nilfs_segctor_do_construct+0x1eac/0x6970 fs/nilfs2/segment.c:2122
nilfs_segctor_construct+0x17b/0x690 fs/nilfs2/segment.c:2478
nilfs_segctor_thread_construct fs/nilfs2/segment.c:2585 [inline]
nilfs_segctor_thread+0x6cd/0xe00 fs/nilfs2/segment.c:2700
kthread+0x70e/0x8a0 kernel/kthread.c:464
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Tested on:
commit: 9c69f888 Merge tag 'bcachefs-2025-05-08' of git://evil..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11a694d4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=91c351a0f6229e67
dashboard link: https://syzkaller.appspot.com/bug?extid=81394db39b0e2ed2db06
compiler: Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
patch: https://syzkaller.appspot.com/x/patch.diff?x=10c74768580000
Powered by blists - more mailing lists