On Mon, 18 Aug 2025 07:33:32 +0000 Ye Weihua <[email protected]> wrote:
> 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. > This looks good to me. Acked-by: Masami Hiramatsu (Google) <[email protected]> Thanks! > Fixes: 4a2b8dda3f870 ("tracing/function-graph-tracer: fix a regression while > suspend to disk") > Signed-off-by: Ye Weihua <[email protected]> > --- > kernel/trace/fgraph.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c > index c5b207992fb4..dac2d58f3949 100644 > --- a/kernel/trace/fgraph.c > +++ b/kernel/trace/fgraph.c > @@ -1391,10 +1391,11 @@ int register_ftrace_graph(struct fgraph_ops *gops) > error: > if (ret) { > ftrace_graph_active--; > gops->saved_func = NULL; > fgraph_lru_release_index(i); > + unregister_pm_notifier(&ftrace_suspend_notifier); > } > return ret; > } > > void unregister_ftrace_graph(struct fgraph_ops *gops) > -- > 2.34.1 > -- Masami Hiramatsu (Google) <[email protected]>
