linux-kernel - [PATCH -tip 5/5] kprobes: Don't call BUG_ON if there is a kprobe in use on free list

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Date:   Tue, 21 Aug 2018 18:39:58 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Ingo Molnar <mingo@...hat.com>
Cc:     "Naveen N . Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
        Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
        "David S . Miller" <davem@...emloft.net>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH -tip 5/5] kprobes: Don't call BUG_ON if there is a kprobe in use on free list

Instead of calling BUG_ON, if we find a kprobe in use on free kprobe
list, just remove it from the list and keep it on kprobe hash list
as same as other in-use kprobes.

Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
 kernel/kprobes.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 63c342e5e6c3..e3420364b415 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -546,8 +546,14 @@ static void do_free_cleaned_kprobes(void)
 	struct optimized_kprobe *op, *tmp;
 
 	list_for_each_entry_safe(op, tmp, &freeing_list, list) {
-		BUG_ON(!kprobe_unused(&op->kp));
 		list_del_init(&op->list);
+		if (!kprobe_unused(&op->kp)) {
+			/*
+			 * This must not happen, but if there is a kprobe
+			 * still in use, keep it on kprobes hash list.
+			 */
+			continue;
+		}
 		free_aggr_kprobe(&op->kp);
 	}
 }