mainline inclusion from mainline-v6.17-rc3 commit edede7a6dcd7435395cf757d053974aaab6ab1c2 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/ICUMJS Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... ---------------------------------------- This warning was triggered during testing on v6.16: notifier callback ftrace_suspend_notifier_call already registered WARNING: CPU: 2 PID: 86 at kernel/notifier.c:23 notifier_chain_register+0x44/0xb0 ... Call Trace: <TASK> blocking_notifier_chain_register+0x34/0x60 register_ftrace_graph+0x330/0x410 ftrace_profile_write+0x1e9/0x340 vfs_write+0xf8/0x420 ? filp_flush+0x8a/0xa0 ? filp_close+0x1f/0x30 ? do_dup2+0xaf/0x160 ksys_write+0x65/0xe0 do_syscall_64+0xa4/0x260 entry_SYSCALL_64_after_hwframe+0x77/0x7f When writing to the function_profile_enabled interface, the notifier was not unregistered after start_graph_tracing failed, causing a warning the next time function_profile_enabled was written. Fixed by adding unregister_pm_notifier in the exception path. Link: https://lore.kernel.org/20250818073332.3890629-1-yeweihua4@huawei.com Fixes: 4a2b8dda3f87 ("tracing/function-graph-tracer: fix a regression while suspend to disk") Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Ye Weihua <yeweihua4@huawei.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Conflicts: kernel/trace/fgraph.c [just contex conflicts] Signed-off-by: Ye Weihua <yeweihua4@huawei.com> --- kernel/trace/fgraph.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index a58da91eadb5..fd8f06c5dcc3 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -609,10 +609,11 @@ int register_ftrace_graph(struct fgraph_ops *gops) ftrace_graph_active++; ret = start_graph_tracing(); if (ret) { ftrace_graph_active--; + unregister_pm_notifier(&ftrace_suspend_notifier); goto out; } ftrace_graph_return = gops->retfunc; @@ -625,10 +626,12 @@ int register_ftrace_graph(struct fgraph_ops *gops) __ftrace_graph_entry = gops->entryfunc; ftrace_graph_entry = ftrace_graph_entry_test; update_function_graph_func(); ret = ftrace_startup(&graph_ops, FTRACE_START_FUNC_RET); + if (ret) + unregister_pm_notifier(&ftrace_suspend_notifier); out: mutex_unlock(&ftrace_lock); return ret; } -- 2.34.1