[tip:perf/core] kprobes: Don't call BUG_ON() if there is a kprobe in use on free list

[tip-bot for Masami Hiramatsu]

Commit-ID:  cbdd96f5586151e48317d90a403941ec23f12660
Gitweb:     https://git.kernel.org/tip/cbdd96f5586151e48317d90a403941ec23f12660
Author:     Masami Hiramatsu <mhiramat@xxxxxxxxxx>
AuthorDate: Tue, 11 Sep 2018 19:21:09 +0900
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 12 Sep 2018 08:01:16 +0200

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@xxxxxxxxxx>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@xxxxxxxxx>
Cc: David S . Miller <davem@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Naveen N . Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: 153666126882.21306.10738207224288507996.stgit@devbox">http://lkml.kernel.org/r/153666126882.21306.10738207224288507996.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 kernel/kprobes.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 63c342e5e6c3..90e98e233647 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 (WARN_ON_ONCE(!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);
 	}
 }