From: Ran Xiaokai <ran.xiaokai@zte.com.cn> mainline inclusion from mainline-v6.15-rc1 commit 7e6b3fcc9c5294aeafed0dbe1a09a1bc899bd0f2 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IBY77F Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- Lockdep reports this deadlock log: osnoise: could not start sampling thread ============================================ WARNING: possible recursive locking detected -------------------------------------------- CPU0 ---- lock(cpu_hotplug_lock); lock(cpu_hotplug_lock); Call Trace: <TASK> print_deadlock_bug+0x282/0x3c0 __lock_acquire+0x1610/0x29a0 lock_acquire+0xcb/0x2d0 cpus_read_lock+0x49/0x120 stop_per_cpu_kthreads+0x7/0x60 start_kthread+0x103/0x120 osnoise_hotplug_workfn+0x5e/0x90 process_one_work+0x44f/0xb30 worker_thread+0x33e/0x5e0 kthread+0x206/0x3b0 ret_from_fork+0x31/0x50 ret_from_fork_asm+0x11/0x20 </TASK> This is the deadlock scenario: osnoise_hotplug_workfn() guard(cpus_read_lock)(); // first lock call start_kthread(cpu) if (IS_ERR(kthread)) { stop_per_cpu_kthreads(); { cpus_read_lock(); // second lock call. Cause the AA deadlock } } It is not necessary to call stop_per_cpu_kthreads() which stops osnoise kthread for every other CPUs in the system if a failure occurs during hotplug of a certain CPU. For start_per_cpu_kthreads(), if the start_kthread() call fails, this function calls stop_per_cpu_kthreads() to handle the error. Therefore, similarly, there is no need to call stop_per_cpu_kthreads() again within start_kthread(). So just remove stop_per_cpu_kthreads() from start_kthread to solve this issue. Cc: stable@vger.kernel.org Link: https://lore.kernel.org/20250321095249.2739397-1-ranxiaokai627@163.com Fixes: c8895e271f79 ("trace/osnoise: Support hotplug operations") Signed-off-by: Ran Xiaokai <ran.xiaokai@zte.com.cn> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Conflicts: kernel/trace/trace_osnoise.c [The conflicts were due to some minor issue.] Signed-off-by: Xiaomeng Zhang <zhangxiaomeng13@huawei.com> --- kernel/trace/trace_osnoise.c | 1 - 1 file changed, 1 deletion(-) diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index cc155590018f..5bd781359d38 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -2038,7 +2038,6 @@ static int start_kthread(unsigned int cpu) if (IS_ERR(kthread)) { pr_err(BANNER "could not start sampling thread\n"); - stop_per_cpu_kthreads(); return -ENOMEM; } -- 2.34.1