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Commit 4da2ce25 authored by Michal Hocko's avatar Michal Hocko Committed by Linus Torvalds
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mm: distinguish CMA and MOVABLE isolation in has_unmovable_pages() 

Joonsoo has noticed that "mm: drop migrate type checks from
has_unmovable_pages" would break CMA allocator because it relies on
has_unmovable_pages returning false even for CMA pageblocks which in
fact don't have to be movable:

 alloc_contig_range
   start_isolate_page_range
     set_migratetype_isolate
       has_unmovable_pages

This is a result of the code sharing between CMA and memory hotplug
while each one has a different idea of what has_unmovable_pages should
return.  This is unfortunate but fixing it properly would require a lot
of code duplication.

Fix the issue by introducing the requested migrate type argument and
special case MIGRATE_CMA case where CMA page blocks are handled
properly.  This will work for memory hotplug because it requires
MIGRATE_MOVABLE.

Link: http://lkml.kernel.org/r/20171019122118.y6cndierwl2vnguj@dhcp22.suse.cz


Signed-off-by: default avatarMichal Hocko <mhocko@suse.com>
Reported-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
Tested-by: default avatarStefan Wahren <stefan.wahren@i2se.com>
Tested-by: default avatarRan Wang <ran.wang_1@nxp.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Yasuaki Ishimatsu <yasu.isimatu@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d7b236e1

include/linux/page-isolation.h

+1 −1
Original line number Original line Diff line number Diff line
@@ -31,7 +31,7 @@ static inline bool is_migrate_isolate(int migratetype) 
#endif

#endif





bool has_unmovable_pages(struct zone *zone, struct page *page, int count,

bool has_unmovable_pages(struct zone *zone, struct page *page, int count,

			 bool skip_hwpoisoned_pages);

			 int migratetype, bool skip_hwpoisoned_pages);

void set_pageblock_migratetype(struct page *page, int migratetype);

void set_pageblock_migratetype(struct page *page, int migratetype);

int move_freepages_block(struct zone *zone, struct page *page,

int move_freepages_block(struct zone *zone, struct page *page,

				int migratetype, int *num_movable);

				int migratetype, int *num_movable);

mm/page_alloc.c

+11 −1
Original line number Original line Diff line number Diff line
@@ -7353,6 +7353,7 @@ void *__init alloc_large_system_hash(const char *tablename, 
 * race condition. So you can't expect this function should be exact.

 * race condition. So you can't expect this function should be exact.

 */

 */

bool has_unmovable_pages(struct zone *zone, struct page *page, int count,

bool has_unmovable_pages(struct zone *zone, struct page *page, int count,

			 int migratetype,

			 bool skip_hwpoisoned_pages)

			 bool skip_hwpoisoned_pages)

{

{

	unsigned long pfn, iter, found;

	unsigned long pfn, iter, found;
@@ -7364,6 +7365,15 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count, 
	if (zone_idx(zone) == ZONE_MOVABLE)

	if (zone_idx(zone) == ZONE_MOVABLE)

		return false;

		return false;





	/*

	 * CMA allocations (alloc_contig_range) really need to mark isolate

	 * CMA pageblocks even when they are not movable in fact so consider

	 * them movable here.

	 */

	if (is_migrate_cma(migratetype) &&

			is_migrate_cma(get_pageblock_migratetype(page)))

		return false;



	pfn = page_to_pfn(page);

	pfn = page_to_pfn(page);

	for (found = 0, iter = 0; iter < pageblock_nr_pages; iter++) {

	for (found = 0, iter = 0; iter < pageblock_nr_pages; iter++) {

		unsigned long check = pfn + iter;

		unsigned long check = pfn + iter;
@@ -7446,7 +7456,7 @@ bool is_pageblock_removable_nolock(struct page *page) 
	if (!zone_spans_pfn(zone, pfn))

	if (!zone_spans_pfn(zone, pfn))

		return false;

		return false;





	return !has_unmovable_pages(zone, page, 0, true);

	return !has_unmovable_pages(zone, page, 0, MIGRATE_MOVABLE, true);

}

}





#if (defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || defined(CONFIG_CMA)

#if (defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || defined(CONFIG_CMA)

mm/page_isolation.c

+5 −5
Original line number Original line Diff line number Diff line
@@ -15,7 +15,7 @@ 
#define CREATE_TRACE_POINTS

#define CREATE_TRACE_POINTS

#include <trace/events/page_isolation.h>

#include <trace/events/page_isolation.h>





static int set_migratetype_isolate(struct page *page,

static int set_migratetype_isolate(struct page *page, int migratetype,

				bool skip_hwpoisoned_pages)

				bool skip_hwpoisoned_pages)

{

{

	struct zone *zone;

	struct zone *zone;
@@ -52,7 +52,7 @@ static int set_migratetype_isolate(struct page *page, 
	 * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.

	 * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.

	 * We just check MOVABLE pages.

	 * We just check MOVABLE pages.

	 */

	 */

	if (!has_unmovable_pages(zone, page, arg.pages_found,

	if (!has_unmovable_pages(zone, page, arg.pages_found, migratetype,

				 skip_hwpoisoned_pages))

				 skip_hwpoisoned_pages))

		ret = 0;

		ret = 0;
@@ -64,14 +64,14 @@ static int set_migratetype_isolate(struct page *page, 
out:

out:

	if (!ret) {

	if (!ret) {

		unsigned long nr_pages;

		unsigned long nr_pages;

		int migratetype = get_pageblock_migratetype(page);

		int mt = get_pageblock_migratetype(page);





		set_pageblock_migratetype(page, MIGRATE_ISOLATE);

		set_pageblock_migratetype(page, MIGRATE_ISOLATE);

		zone->nr_isolate_pageblock++;

		zone->nr_isolate_pageblock++;

		nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE,

		nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE,

									NULL);

									NULL);





		__mod_zone_freepage_state(zone, -nr_pages, migratetype);

		__mod_zone_freepage_state(zone, -nr_pages, mt);

	}

	}





	spin_unlock_irqrestore(&zone->lock, flags);

	spin_unlock_irqrestore(&zone->lock, flags);
@@ -183,7 +183,7 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, 
	     pfn += pageblock_nr_pages) {

	     pfn += pageblock_nr_pages) {

		page = __first_valid_page(pfn, pageblock_nr_pages);

		page = __first_valid_page(pfn, pageblock_nr_pages);

		if (page &&

		if (page &&

		    set_migratetype_isolate(page, skip_hwpoisoned_pages)) {

		    set_migratetype_isolate(page, migratetype, skip_hwpoisoned_pages)) {

			undo_pfn = pfn;

			undo_pfn = pfn;

			goto undo;

			goto undo;

		}

		}