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Commit 49071d43 authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds
Browse files

thp: add debugfs handle to split all huge pages 



Writing 1 into 'split_huge_pages' will try to find and split all huge
pages in the system.  This is useful for debuging.

[akpm@linux-foundation.org: fix printk text, per Vlastimil]
Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b20ce5e0

mm/huge_memory.c

+59 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <linux/freezer.h>

#include <linux/mman.h>

#include <linux/pagemap.h>

#include <linux/debugfs.h>

#include <linux/migrate.h>

#include <linux/hashtable.h>

#include <linux/userfaultfd_k.h>
@@ -3350,3 +3351,61 @@ static struct shrinker deferred_split_shrinker = { 
	.scan_objects = deferred_split_scan,

	.seeks = DEFAULT_SEEKS,

};



#ifdef CONFIG_DEBUG_FS

static int split_huge_pages_set(void *data, u64 val)

{

	struct zone *zone;

	struct page *page;

	unsigned long pfn, max_zone_pfn;

	unsigned long total = 0, split = 0;



	if (val != 1)

		return -EINVAL;



	for_each_populated_zone(zone) {

		max_zone_pfn = zone_end_pfn(zone);

		for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {

			if (!pfn_valid(pfn))

				continue;



			page = pfn_to_page(pfn);

			if (!get_page_unless_zero(page))

				continue;



			if (zone != page_zone(page))

				goto next;



			if (!PageHead(page) || !PageAnon(page) ||

					PageHuge(page))

				goto next;



			total++;

			lock_page(page);

			if (!split_huge_page(page))

				split++;

			unlock_page(page);

next:

			put_page(page);

		}

	}



	pr_info("%lu of %lu THP split", split, total);



	return 0;

}

DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,

		"%llu\n");



static int __init split_huge_pages_debugfs(void)

{

	void *ret;



	ret = debugfs_create_file("split_huge_pages", 0644, NULL, NULL,

			&split_huge_pages_fops);

	if (!ret)

		pr_warn("Failed to create split_huge_pages in debugfs");

	return 0;

}

late_initcall(split_huge_pages_debugfs);

#endif