[PATCH 3/4] oom: oom_kill doesn't kill vfork parent(or child)

[KOSAKI Motohiro]

Subject: [PATCH] oom: oom_kill doesn't kill vfork parent(or child).

Current oom_kill doesn't only kill victim process, but also kill
mm shread task. it mean vfork parent will be killed.

but, That's bogus. another process have another oom_adj. we shouldn't
ignore their oom_adj (it might have OOM_DISABLE).

following caller hit the minefield.

---------------------------------------
        switch (constraint) {
        case CONSTRAINT_MEMORY_POLICY:
                oom_kill_process(current, gfp_mask, order, 0, NULL,
                                "No available memory (MPOL_BIND)");
                break;


Note: force_sig(SIGKILL) send SIGKILL to all thread in the process.
We don't need to care multi thread in here.


Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Paul Menage <menage@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>,
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>,
---
 mm/oom_kill.c |   12 ------------
 1 file changed, 12 deletions(-)

Index: b/mm/oom_kill.c
===================================================================
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -399,23 +399,11 @@ static void __oom_kill_task(struct task_
 
 static int oom_kill_task(struct task_struct *p)
 {
-	struct task_struct *g, *q;
-
 	if (get_oom_adj(p) == OOM_DISABLE)
 		return 1;
 
 	__oom_kill_task(p, 1);
 
-	/*
-	 * kill all processes that share the ->mm (i.e. all threads),
-	 * but are in a different thread group. Don't let them have access
-	 * to memory reserves though, otherwise we might deplete all memory.
-	 */
-	do_each_thread(g, q) {
-		if (q->mm == p->mm && !same_thread_group(q, p))
-			force_sig(SIGKILL, q);
-	} while_each_thread(g, q);
-
 	return 0;
 }
 


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