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mm: fix zone_watermark_ok_safe() accounting of isolated pages

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Commit 702d1a6e07 ("memory-hotplug: fix kswapd looping forever
problem") added an isolated pageblocks counter (nr_pageblock_isolate in
struct zone) and used it to adjust free pages counter in
zone_watermark_ok_safe() to prevent kswapd looping forever problem.

Then later, commit 2139cbe627 ("cma: fix counting of isolated pages")
fixed accounting of isolated pages in global free pages counter.  It
made the previous zone_watermark_ok_safe() fix unnecessary and
potentially harmful (cause now isolated pages may be accounted twice
making free pages counter incorrect).

This patch removes the special isolated pageblocks counter altogether
which fixes zone_watermark_ok_safe() free pages check.

Reported-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Aaditya Kumar <aaditya.kumar.30@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Bartlomiej Zolnierkiewicz 2013-01-04 15:35:08 -08:00 committed by Linus Torvalds
parent 358e419f82
commit a458431e17
3 changed files with 2 additions and 59 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
include/linux/mmzone.h
View File

@ -503,14 +503,6 @@ struct zone {
* rarely used fields:
*/
const char *name;
#ifdef CONFIG_MEMORY_ISOLATION
/*
* the number of MIGRATE_ISOLATE *pageblock*.
* We need this for free page counting. Look at zone_watermark_ok_safe.
* It's protected by zone->lock
*/
int nr_pageblock_isolate;
#endif
} ____cacheline_internodealigned_in_smp;
typedef enum {

27
mm/page_alloc.c
View File

@ -221,11 +221,6 @@ EXPORT_SYMBOL(nr_online_nodes);
int page_group_by_mobility_disabled __read_mostly;
/*
* NOTE:
* Don't use set_pageblock_migratetype(page, MIGRATE_ISOLATE) directly.
* Instead, use {un}set_pageblock_isolate.
*/
void set_pageblock_migratetype(struct page *page, int migratetype)
{
@ -1655,20 +1650,6 @@ static bool __zone_watermark_ok(struct zone *z, int order, unsigned long mark,
return true;
}
#ifdef CONFIG_MEMORY_ISOLATION
static inline unsigned long nr_zone_isolate_freepages(struct zone *zone)
{
if (unlikely(zone->nr_pageblock_isolate))
return zone->nr_pageblock_isolate * pageblock_nr_pages;
return 0;
}
#else
static inline unsigned long nr_zone_isolate_freepages(struct zone *zone)
{
return 0;
}
#endif
bool zone_watermark_ok(struct zone *z, int order, unsigned long mark,
int classzone_idx, int alloc_flags)
{
@ -1684,14 +1665,6 @@ bool zone_watermark_ok_safe(struct zone *z, int order, unsigned long mark,
if (z->percpu_drift_mark && free_pages < z->percpu_drift_mark)
free_pages = zone_page_state_snapshot(z, NR_FREE_PAGES);
/*
* If the zone has MIGRATE_ISOLATE type free pages, we should consider
* it. nr_zone_isolate_freepages is never accurate so kswapd might not
* sleep although it could do so. But this is more desirable for memory
* hotplug than sleeping which can cause a livelock in the direct
* reclaim path.
*/
free_pages -= nr_zone_isolate_freepages(z);
return __zone_watermark_ok(z, order, mark, classzone_idx, alloc_flags,
free_pages);
}

26
mm/page_isolation.c
View File

@ -8,28 +8,6 @@
#include <linux/memory.h>
#include "internal.h"
/* called while holding zone->lock */
static void set_pageblock_isolate(struct page *page)
{
if (get_pageblock_migratetype(page) == MIGRATE_ISOLATE)
return;
set_pageblock_migratetype(page, MIGRATE_ISOLATE);
page_zone(page)->nr_pageblock_isolate++;
}
/* called while holding zone->lock */
static void restore_pageblock_isolate(struct page *page, int migratetype)
{
struct zone *zone = page_zone(page);
if (WARN_ON(get_pageblock_migratetype(page) != MIGRATE_ISOLATE))
return;
BUG_ON(zone->nr_pageblock_isolate <= 0);
set_pageblock_migratetype(page, migratetype);
zone->nr_pageblock_isolate--;
}
int set_migratetype_isolate(struct page *page, bool skip_hwpoisoned_pages)
{
struct zone *zone;
@ -80,7 +58,7 @@ int set_migratetype_isolate(struct page *page, bool skip_hwpoisoned_pages)
unsigned long nr_pages;
int migratetype = get_pageblock_migratetype(page);
set_pageblock_isolate(page);
set_pageblock_migratetype(page, MIGRATE_ISOLATE);
nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE);
__mod_zone_freepage_state(zone, -nr_pages, migratetype);
@ -103,7 +81,7 @@ void unset_migratetype_isolate(struct page *page, unsigned migratetype)
goto out;
nr_pages = move_freepages_block(zone, page, migratetype);
__mod_zone_freepage_state(zone, nr_pages, migratetype);
restore_pageblock_isolate(page, migratetype);
set_pageblock_migratetype(page, migratetype);
out:
spin_unlock_irqrestore(&zone->lock, flags);
}