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Commit ef08e3b4 authored by Paul Jackson's avatar Paul Jackson Committed by Linus Torvalds
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[PATCH] cpusets: confine oom_killer to mem_exclusive cpuset 



Now the real motivation for this cpuset mem_exclusive patch series seems
trivial.

This patch keeps a task in or under one mem_exclusive cpuset from provoking an
oom kill of a task under a non-overlapping mem_exclusive cpuset.  Since only
interrupt and GFP_ATOMIC allocations are allowed to escape mem_exclusive
containment, there is little to gain from oom killing a task under a
non-overlapping mem_exclusive cpuset, as almost all kernel and user memory
allocation must come from disjoint memory nodes.

This patch enables configuring a system so that a runaway job under one
mem_exclusive cpuset cannot cause the killing of a job in another such cpuset
that might be using very high compute and memory resources for a prolonged
time.

Signed-off-by: default avatarPaul Jackson <pj@sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 9bf2229f

include/linux/cpuset.h

+6 −0
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ void cpuset_update_current_mems_allowed(void); 
void cpuset_restrict_to_mems_allowed(unsigned long *nodes);

int cpuset_zonelist_valid_mems_allowed(struct zonelist *zl);

extern int cpuset_zone_allowed(struct zone *z, unsigned int __nocast gfp_mask);

extern int cpuset_excl_nodes_overlap(const struct task_struct *p);

extern struct file_operations proc_cpuset_operations;

extern char *cpuset_task_status_allowed(struct task_struct *task, char *buffer);
@@ -54,6 +55,11 @@ static inline int cpuset_zone_allowed(struct zone *z, 
	return 1;

}



static inline int cpuset_excl_nodes_overlap(const struct task_struct *p)

{

	return 1;

}



static inline char *cpuset_task_status_allowed(struct task_struct *task,

							char *buffer)

{

kernel/cpuset.c

+33 −0
Original line number Diff line number Diff line
@@ -1688,6 +1688,39 @@ int cpuset_zone_allowed(struct zone *z, unsigned int __nocast gfp_mask) 
	return allowed;

}



/**

 * cpuset_excl_nodes_overlap - Do we overlap @p's mem_exclusive ancestors?

 * @p: pointer to task_struct of some other task.

 *

 * Description: Return true if the nearest mem_exclusive ancestor

 * cpusets of tasks @p and current overlap.  Used by oom killer to

 * determine if task @p's memory usage might impact the memory

 * available to the current task.

 *

 * Acquires cpuset_sem - not suitable for calling from a fast path.

 **/



int cpuset_excl_nodes_overlap(const struct task_struct *p)

{

	const struct cpuset *cs1, *cs2;	/* my and p's cpuset ancestors */

	int overlap = 0;		/* do cpusets overlap? */



	down(&cpuset_sem);

	cs1 = current->cpuset;

	if (!cs1)

		goto done;		/* current task exiting */

	cs2 = p->cpuset;

	if (!cs2)

		goto done;		/* task p is exiting */

	cs1 = nearest_exclusive_ancestor(cs1);

	cs2 = nearest_exclusive_ancestor(cs2);

	overlap = nodes_intersects(cs1->mems_allowed, cs2->mems_allowed);

done:

	up(&cpuset_sem);



	return overlap;

}



/*

 * proc_cpuset_show()

 *  - Print tasks cpuset path into seq_file.

mm/oom_kill.c

+5 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/swap.h>

#include <linux/timex.h>

#include <linux/jiffies.h>

#include <linux/cpuset.h>



/* #define DEBUG */
@@ -152,6 +153,10 @@ static struct task_struct * select_bad_process(void) 
			continue;

		if (p->oomkilladj == OOM_DISABLE)

			continue;

		/* If p's nodes don't overlap ours, it won't help to kill p. */

		if (!cpuset_excl_nodes_overlap(p))

			continue;



		/*

		 * This is in the process of releasing memory so for wait it

		 * to finish before killing some other task by mistake.