From: Michal Hocko <mhocko@xxxxxxxx>
Subject: 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@xxxxxxxxxxxxxx
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Reported-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Tested-by: Stefan Wahren <stefan.wahren@xxxxxxxx>
Tested-by: Ran Wang <ran.wang_1@xxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Igor Mammedov <imammedo@xxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Reza Arbab <arbab@xxxxxxxxxxxxxxxxxx>
Cc: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Cc: Xishi Qiu <qiuxishi@xxxxxxxxxx>
Cc: Yasuaki Ishimatsu <yasu.isimatu@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/page-isolation.h | 2 +-
mm/page_alloc.c | 12 +++++++++++-
mm/page_isolation.c | 10 +++++-----
3 files changed, 17 insertions(+), 7 deletions(-)
diff -puN include/linux/page-isolation.h~mm-distinguish-cma-and-movable-isolation-in-has_unmovable_pages include/linux/page-isolation.h
--- a/include/linux/page-isolation.h~mm-distinguish-cma-and-movable-isolation-in-has_unmovable_pages
+++ a/include/linux/page-isolation.h
@@ -31,7 +31,7 @@ static inline bool is_migrate_isolate(in
#endif
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);
int move_freepages_block(struct zone *zone, struct page *page,
int migratetype, int *num_movable);
diff -puN mm/page_alloc.c~mm-distinguish-cma-and-movable-isolation-in-has_unmovable_pages mm/page_alloc.c
--- a/mm/page_alloc.c~mm-distinguish-cma-and-movable-isolation-in-has_unmovable_pages
+++ a/mm/page_alloc.c
@@ -7353,6 +7353,7 @@ void *__init alloc_large_system_hash(con
* race condition. So you can't expect this function should be exact.
*/
bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
+ int migratetype,
bool skip_hwpoisoned_pages)
{
unsigned long pfn, iter, found;
@@ -7364,6 +7365,15 @@ bool has_unmovable_pages(struct zone *zo
if (zone_idx(zone) == ZONE_MOVABLE)
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);
for (found = 0, iter = 0; iter < pageblock_nr_pages; iter++) {
unsigned long check = pfn + iter;
@@ -7446,7 +7456,7 @@ bool is_pageblock_removable_nolock(struc
if (!zone_spans_pfn(zone, pfn))
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)
diff -puN mm/page_isolation.c~mm-distinguish-cma-and-movable-isolation-in-has_unmovable_pages mm/page_isolation.c
--- a/mm/page_isolation.c~mm-distinguish-cma-and-movable-isolation-in-has_unmovable_pages
+++ a/mm/page_isolation.c
@@ -15,7 +15,7 @@
#define CREATE_TRACE_POINTS
#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)
{
struct zone *zone;
@@ -52,7 +52,7 @@ static int set_migratetype_isolate(struc
* FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
* 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))
ret = 0;
@@ -64,14 +64,14 @@ static int set_migratetype_isolate(struc
out:
if (!ret) {
unsigned long nr_pages;
- int migratetype = get_pageblock_migratetype(page);
+ int mt = get_pageblock_migratetype(page);
set_pageblock_migratetype(page, MIGRATE_ISOLATE);
zone->nr_isolate_pageblock++;
nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE,
NULL);
- __mod_zone_freepage_state(zone, -nr_pages, migratetype);
+ __mod_zone_freepage_state(zone, -nr_pages, mt);
}
spin_unlock_irqrestore(&zone->lock, flags);
@@ -183,7 +183,7 @@ int start_isolate_page_range(unsigned lo
pfn += pageblock_nr_pages) {
page = __first_valid_page(pfn, pageblock_nr_pages);
if (page &&
- set_migratetype_isolate(page, skip_hwpoisoned_pages)) {
+ set_migratetype_isolate(page, migratetype, skip_hwpoisoned_pages)) {
undo_pfn = pfn;
goto undo;
}
_
--
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