From 70d78fe7c8b640b5acfad56ad341985b3810998a Mon Sep 17 00:00:00 2001
From: Andrey Ryabinin <aryabinin@virtuozzo.com>
Date: Thu, 10 Nov 2016 10:46:38 -0800
Subject: [PATCH] coredump: fix unfreezable coredumping task
It could be not possible to freeze coredumping task when it waits for
'core_state->startup' completion, because threads are frozen in
get_signal() before they got a chance to complete 'core_state->startup'.
Inability to freeze a task during suspend will cause suspend to fail.
Also CRIU uses cgroup freezer during dump operation. So with an
unfreezable task the CRIU dump will fail because it waits for a
transition from 'FREEZING' to 'FROZEN' state which will never happen.
Use freezer_do_not_count() to tell freezer to ignore coredumping task
while it waits for core_state->startup completion.
Link: http://lkml.kernel.org/r/1475225434-3753-1-git-send-email-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Tejun Heo <tj@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
fs/coredump.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/coredump.c b/fs/coredump.c
index 281b768000e66..eb9c92c9b20f5 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -1,6 +1,7 @@
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/fdtable.h>
+#include <linux/freezer.h>
#include <linux/mm.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
@@ -423,7 +424,9 @@ static int coredump_wait(int exit_code, struct core_state *core_state)
if (core_waiters > 0) {
struct core_thread *ptr;
+ freezer_do_not_count();
wait_for_completion(&core_state->startup);
+ freezer_count();
/*
* Wait for all the threads to become inactive, so that
* all the thread context (extended register state, like
--
2.39.5