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Tue, 20 Oct 2026 06:04:12 -0700 (PDT) Received: from localhost ([111.228.63.84]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-cd6549fb556sm5267685a12.22.2026.10.20.06.04.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Oct 2026 06:04:12 -0700 (PDT) From: Cen Zhang To: mark@fasheh.com, jlbec@evilplan.org, joseph.qi@linux.alibaba.com Cc: heming.zhao@suse.com, ocfs2-devel@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, baijiaju1990@gmail.com, jjzuming@gmail.com, zzzccc427@gmail.com Subject: [PATCH] ocfs2/dlm: drain join handlers before releasing module text Date: Tue, 20 Oct 2026 21:04:04 +0800 Message-Id: X-Mailer: git-send-email 2.34.1 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The code for a registered DLM handler must remain resident until its last invocation finishes. dlm_unregister_net_handlers() only removes dlm_join_handlers from the o2net registry. o2net_handler_get() takes a kref on the wrapper, but that reference does not pin ocfs2_dlm text. o2net_process_message() calls nh_func after dropping o2net_handler_lock. With CONFIG_OCFS2_FS_O2CB=m, ocfs2_dlm can be loaded independently of ocfs2_stack_o2cb while nodemanager continues handling messages from a configured, heartbeating peer. If no dependent module or module reference prevents normal unload, the following ordering is possible: Receive worker Module unload -------------- ------------- o2net_handler_get() take wrapper kref drop handler lock dlm_exit() unregister handlers release DLM module text call saved nh_func in released module text Use o2net_unregister_and_flush_handler_list() in the shared DLM unregister helper. It first prevents new lookups, then waits for the ordered o2net workqueue to drain, including a concurrent destruction of that queue. The acquired invocation therefore finishes before dlm_exit() returns and the loader releases the callback code. The same helper also covers partial registration and dlm_init() error unwind before module memory is released. Oops report as below: Oops: int3: 0000 [#1] SMP KASAN NOPTI CPU: 2 UID: 0 PID: 54 Comm: kworker/u16:3 Not tainted 7.3.0-rc4-next-20260921-pmb-ocfs2-functional-v1+ #1 PREEMPT(lazy) Hardware identification omitted. Workqueue: o2net o2net_rx_until_empty [ocfs2_nodemanager] RIP: 0010:0xffffffffc0423871 Code: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc Register dump omitted. Call Trace: ? o2net_rx_until_empty+0x19b1/0x3300 [ocfs2_nodemanager] ? __pfx_o2net_rx_until_empty+0x10/0x10 [ocfs2_nodemanager] ? lock_acquire+0x190/0x300 ? process_one_work+0x935/0x1b40 ? process_one_work+0x834/0x1b40 ? srso_alias_return_thunk+0x5/0xfbef5 ? lock_release+0xc8/0x290 ? srso_alias_return_thunk+0x5/0xfbef5 ? process_one_work+0x9a8/0x1b40 ? __pfx_process_one_work+0x10/0x10 ? lock_acquire+0x190/0x300 ? lock_is_held_type+0x8f/0x100 ? srso_alias_return_thunk+0x5/0xfbef5 ? worker_thread+0x65c/0xe40 ? srso_alias_return_thunk+0x5/0xfbef5 ? __kthread_parkme+0x177/0x220 ? srso_alias_return_thunk+0x5/0xfbef5 ? __pfx_worker_thread+0x10/0x10 ? kthread+0x351/0x460 ? srso_alias_return_thunk+0x5/0xfbef5 ? __pfx_kthread+0x10/0x10 ? ret_from_fork+0x659/0x940 ? __pfx_ret_from_fork+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 ? __switch_to+0x74f/0xf70 ? __pfx_kthread+0x10/0x10 ? ret_from_fork_asm+0x1a/0x30 Modules linked in: ocfs2_nodemanager [last unloaded: ocfs2_dlm] ---[ end trace 0000000000000000 ]--- Fixes: 6714d8e86bf4 ("[PATCH] OCFS2: The Second Oracle Cluster Filesystem") Cc: Signed-off-by: Cen Zhang Assisted-by: LLM --- fs/ocfs2/dlm/dlmdomain.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c index 97bb9400e24b..0f4d29cbce81 100644 --- a/fs/ocfs2/dlm/dlmdomain.c +++ b/fs/ocfs2/dlm/dlmdomain.c @@ -2215,7 +2215,7 @@ static LIST_HEAD(dlm_join_handlers); static void dlm_unregister_net_handlers(void) { - o2net_unregister_handler_list(&dlm_join_handlers); + o2net_unregister_and_flush_handler_list(&dlm_join_handlers); } static int dlm_register_net_handlers(void)