[patch v2] oom: thaw threads if oom killed thread is frozen before deferring

[David Rientjes <rientjes@google.com>]

If a thread has been oom killed and is frozen, thaw it before returning
to the page allocator.  Otherwise, it can stay frozen indefinitely and
no memory will be freed.

Reported-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: David Rientjes <rientjes@google.com>
---
 v2: adds the missing header file include, the resend patch was based on a 
     previous patch from Michal that is no longer needed if this is 
     applied.

 mm/oom_kill.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 626303b..d897262 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -32,6 +32,7 @@
 #include <linux/mempolicy.h>
 #include <linux/security.h>
 #include <linux/ptrace.h>
+#include <linux/freezer.h>
 
 int sysctl_panic_on_oom;
 int sysctl_oom_kill_allocating_task;
@@ -317,8 +318,11 @@ static struct task_struct *select_bad_process(unsigned int *ppoints,
 		 * blocked waiting for another task which itself is waiting
 		 * for memory. Is there a better alternative?
 		 */
-		if (test_tsk_thread_flag(p, TIF_MEMDIE))
+		if (test_tsk_thread_flag(p, TIF_MEMDIE)) {
+			if (unlikely(frozen(p)))
+				thaw_process(p);
 			return ERR_PTR(-1UL);
+		}
 		if (!p->mm)
 			continue;
 

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