6.16-stable review patch. If anyone has any objections, please let me know.
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From: Masami Hiramatsu (Google) mhiramat@kernel.org
commit a3e892ab0fc287389176eabdcd74234508f6e52d upstream.
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@m...
Fixes: 4346ba160409 ("fprobe: Rewrite fprobe on function-graph tracer") Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu (Google) mhiramat@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/trace/fprobe.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -352,7 +352,7 @@ static void fprobe_return(struct ftrace_ 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_ } curr += size; } - preempt_enable(); + preempt_enable_notrace(); } NOKPROBE_SYMBOL(fprobe_return);