From a3e892ab0fc287389176eabdcd74234508f6e52d Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Tue, 29 Jul 2025 08:47:03 +0900 Subject: [PATCH] tracing: fprobe: Fix infinite recursion using preempt_*_notrace() Since preempt_count_add/del() are tracable functions, it is not allowed to use preempt_disable/enable() in ftrace handlers. Without this fix, probing on `preempt_count_add%return` will cause an infinite recursion of fprobes. To fix this problem, use preempt_disable/enable_notrace() in fprobe_return(). Link: https://lore.kernel.org/all/175374642359.1471729.1054175011228386560.stgit@mhiramat.tok.corp.google.com/ Fixes: 4346ba160409 ("fprobe: Rewrite fprobe on function-graph tracer") Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/fprobe.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c index ba7ff14f5339b..f9b3aa9afb178 100644 --- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -352,7 +352,7 @@ static void fprobe_return(struct ftrace_graph_ret *trace, size_words = SIZE_IN_LONG(size); ret_ip = ftrace_regs_get_instruction_pointer(fregs); - preempt_disable(); + preempt_disable_notrace(); curr = 0; while (size_words > curr) { @@ -368,7 +368,7 @@ static void fprobe_return(struct ftrace_graph_ret *trace, } curr += size; } - preempt_enable(); + preempt_enable_notrace(); } NOKPROBE_SYMBOL(fprobe_return); -- 2.47.2