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From: Masami Hiramatsu <>
To: Ingo Molnar <>
Cc: Andy Lutomirski <>,
	Alexei Starovoitov <>,
	Oleg Nesterov <>,
	Peter Zijlstra <>,
	"H . Peter Anvin" <>,
	Thomas Gleixner <>, X86 ML <>,
	Borislav Petkov <>,, Masami Hiramatsu <>,
Subject: [PATCH -tip] kprobes/x86: Use preempt_enable() in optimized_callback()
Date: Sat, 20 Oct 2018 18:47:53 +0900
Message-ID: <154002887331.7627.10194920925792947001.stgit@devbox> (raw)

Since commit a19b2e3d7839 ("kprobes/x86: Remove IRQ disabling from
ftrace-based/optimized kprobes”) removes local_irq_save/restore()
from optimized_callback(), the handler does not protected against
reschedule interrupt. If it is able to be preempted (rescheduled)
by such interrupt, we don't need to use _no_resched macro.
Let's use preempt_enable() instead.

Fixes: a19b2e3d7839 ("kprobes/x86: Remove IRQ disabling from ftrace-based/optimized kprobes”)
Reported-by: Nadav Amit <>
Signed-off-by: Masami Hiramatsu <>
 arch/x86/kernel/kprobes/opt.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index eaf02f2e7300..40b16b270656 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -179,7 +179,7 @@ optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs)
 		opt_pre_handler(&op->kp, regs);
 		__this_cpu_write(current_kprobe, NULL);
-	preempt_enable_no_resched();
+	preempt_enable();

             reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-20  9:47 Masami Hiramatsu [this message]
2018-10-21 20:42 ` Peter Zijlstra
2018-10-22  1:33 ` [tip:perf/core] " tip-bot for Masami Hiramatsu

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