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Thu, 08 Jan 2026 10:36:59 -0800 (PST) Date: Fri, 9 Jan 2026 00:06:52 +0530 From: Prithvi To: joseph.qi@linux.alibaba.com Cc: mark@fasheh.com, jlbec@evilplan.org, heming.zhao@suse.com, ocfs2-devel@lists.linux.dev, linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linux.dev, skhan@linuxfoundation.org, david.hunter.linux@gmail.com, khalid@kernel.org Subject: Re: [PATCH] ocfs2: Fix circular locking dependency in ocfs2_del_inode_from_orphan() Message-ID: <20260108183652.ro4xueuj6itfaph3@inspiron> References: <20260106125100.327980-1-activprithvi@gmail.com> <94b4189d-dfb6-4443-a336-abbae89d36ad@linux.alibaba.com> Precedence: bulk X-Mailing-List: linux-kernel-mentees@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <94b4189d-dfb6-4443-a336-abbae89d36ad@linux.alibaba.com> On Thu, Jan 08, 2026 at 09:29:11AM +0800, Joseph Qi wrote: > > > On 2026/1/6 20:51, Prithvi Tambewagh wrote: > > A possible circular locking dependency in ocfs2_del_inode_from_orphan() > > is detected by syzbot, which occurs due to change in the sequence of > > acquiring locks. The existing chain is: > > > > &ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE] --> &dquot->dq_lock --> > > &ocfs2_quota_ip_alloc_sem_key > > > > In ocfs2_dio_end_io_write(), &ocfs2_quota_ip_alloc_sem_key is acquired, > > and then ocfs2_del_inode_from_orphan() is called, which acquires > > &ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]. This opposes the > > existing dependency chain: > > > > IIUC, ocfs2_dio_end_io_write() only gets the &ocfs2_file_ip_alloc_sem_key. > So how it happens? > > Thanks, > Joseph > IIUC that would be the case when ocfs2_dio_end_io_write() operates on normal files. However, according to the report of the bug, ocfs2_dio_end_io_write() is holding &ocfs2_quota_ip_alloc_sem_key so I think due to random fuzzing by syzkaller, the function is curently operating on a quota file. Then it calls ocfs2_del_inode_from_orphan() which tries to acquire &ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]. According to the existing dependency chain, after acquiring it, &ocfs2_quota_ip_alloc_sem_key can be acquired. But the existing code in ocfs2_dio_end_io_write() first acquires &ocfs2_quota_ip_alloc_sem_key, thus triggering the circular dependency warning. Thanks, Prithvi > > -> #3 (&ocfs2_quota_ip_alloc_sem_key){++++}-{4:4}: > > lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 > > down_write+0x3a/0x50 kernel/locking/rwsem.c:1590 > > ocfs2_create_local_dquot+0x19d/0x1a40 fs/ocfs2/quota_local.c:1227 > > ocfs2_acquire_dquot+0x80f/0xb30 fs/ocfs2/quota_global.c:883 > > dqget+0x7c1/0xf20 fs/quota/dquot.c:980 > > __dquot_initialize+0x3b3/0xcb0 fs/quota/dquot.c:1508 > > ocfs2_get_init_inode+0x13b/0x1b0 fs/ocfs2/namei.c:205 > > ocfs2_mknod+0x863/0x2050 fs/ocfs2/namei.c:313 > > ocfs2_create+0x1a5/0x440 fs/ocfs2/namei.c:676 > > lookup_open fs/namei.c:3796 [inline] > > open_last_lookups fs/namei.c:3895 [inline] > > path_openat+0x1500/0x3840 fs/namei.c:4131 > > 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 (&dquot->dq_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 > > wait_on_dquot fs/quota/dquot.c:357 [inline] > > dqget+0x73a/0xf20 fs/quota/dquot.c:975 > > __dquot_initialize+0x3b3/0xcb0 fs/quota/dquot.c:1508 > > ocfs2_get_init_inode+0x13b/0x1b0 fs/ocfs2/namei.c:205 > > ocfs2_mknod+0x863/0x2050 fs/ocfs2/namei.c:313 > > ocfs2_create+0x1a5/0x440 fs/ocfs2/namei.c:676 > > lookup_open fs/namei.c:3796 [inline] > > open_last_lookups fs/namei.c:3895 [inline] > > path_openat+0x1500/0x3840 fs/namei.c:4131 > > 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 > > > > -> #1 (&ocfs2_sysfile_lock_key[INODE_ALLOC_SYSTEM_INODE]){+.+.}-{4:4}: > > lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 > > down_write+0x3a/0x50 kernel/locking/rwsem.c:1590 > > inode_lock include/linux/fs.h:980 [inline] > > ocfs2_remove_inode fs/ocfs2/inode.c:731 [inline] > > ocfs2_wipe_inode fs/ocfs2/inode.c:894 [inline] > > ocfs2_delete_inode fs/ocfs2/inode.c:1155 [inline] > > ocfs2_evict_inode+0x153d/0x40d0 fs/ocfs2/inode.c:1295 > > evict+0x504/0x9c0 fs/inode.c:810 > > do_unlinkat+0x39f/0x570 fs/namei.c:4744 > > __do_sys_unlinkat fs/namei.c:4778 [inline] > > __se_sys_unlinkat fs/namei.c:4771 [inline] > > __x64_sys_unlinkat+0xd3/0xf0 fs/namei.c:4771 > > 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 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{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_write+0x3a/0x50 kernel/locking/rwsem.c:1590 > > inode_lock include/linux/fs.h:980 [inline] > > ocfs2_del_inode_from_orphan+0x134/0x740 fs/ocfs2/namei.c:2730 > > ocfs2_dio_end_io_write fs/ocfs2/aops.c:2306 [inline] > > ocfs2_dio_end_io+0x47b/0x1100 fs/ocfs2/aops.c:2404 > > dio_complete+0x25e/0x790 fs/direct-io.c:281 > > __blockdev_direct_IO+0x2bc0/0x31f0 fs/direct-io.c:1303 > > ocfs2_direct_IO+0x260/0x2d0 fs/ocfs2/aops.c:2441 > > generic_file_direct_write+0x1dc/0x3e0 mm/filemap.c:4189 > > __generic_file_write_iter+0x120/0x240 mm/filemap.c:4358 > > ocfs2_file_write_iter+0x157d/0x1d20 fs/ocfs2/file.c:2469 > > iter_file_splice_write+0x97a/0x10f0 fs/splice.c:738 > > do_splice_from fs/splice.c:938 [inline] > > direct_splice_actor+0x104/0x160 fs/splice.c:1161 > > splice_direct_to_actor+0x5b3/0xcd0 fs/splice.c:1105 > > do_splice_direct_actor fs/splice.c:1204 [inline] > > do_splice_direct+0x187/0x270 fs/splice.c:1230 > > do_sendfile+0x4ec/0x7f0 fs/read_write.c:1370 > > __do_sys_sendfile64 fs/read_write.c:1431 [inline] > > __se_sys_sendfile64+0x13e/0x190 fs/read_write.c:1417 > > 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 > > > > Fix this by acquiring &ocfs2_quota_ip_alloc_sem_key after acquiring > > &ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE], effectively calling > > down_write(&oi->ip_alloc_sem) after the call to > > ocfs2_del_inode_from_orphan(). > > > > Reported-by: syzbot+78359d5fbb04318c35e9@syzkaller.appspotmail.com > > Closes: https://syzkaller.appspot.com/bug?extid=78359d5fbb04318c35e9 > > Tested-by: syzbot+78359d5fbb04318c35e9@syzkaller.appspotmail.com > > Cc: stable@vger.kernel.org > > Signed-off-by: Prithvi Tambewagh > > --- > > fs/ocfs2/aops.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c > > index 76c86f1c2b1c..586e3b74d782 100644 > > --- a/fs/ocfs2/aops.c > > +++ b/fs/ocfs2/aops.c > > @@ -2295,8 +2295,6 @@ static int ocfs2_dio_end_io_write(struct inode *inode, > > goto out; > > } > > > > - down_write(&oi->ip_alloc_sem); > > - > > /* Delete orphan before acquire i_rwsem. */ > > if (dwc->dw_orphaned) { > > BUG_ON(dwc->dw_writer_pid != task_pid_nr(current)); > > @@ -2309,6 +2307,8 @@ static int ocfs2_dio_end_io_write(struct inode *inode, > > mlog_errno(ret); > > } > > > > + down_write(&oi->ip_alloc_sem); > > + > > di = (struct ocfs2_dinode *)di_bh->b_data; > > > > ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode), di_bh); > > > > base-commit: 765e56e41a5af2d456ddda6cbd617b9d3295ab4e >