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Commit cfd3da1e authored by Mel Gorman's avatar Mel Gorman Committed by Marek Szyprowski
Browse files

mm: Serialize access to min_free_kbytes 



There is a race between the min_free_kbytes sysctl, memory hotplug
and transparent hugepage support enablement.  Memory hotplug uses a
zonelists_mutex to avoid a race when building zonelists. Reuse it to
serialise watermark updates.

[a.p.zijlstra@chello.nl: Older patch fixed the race with spinlock]
Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
Signed-off-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Tested-by: default avatarBarry Song <Baohua.Song@csr.com>
parent 0815f3d8

mm/page_alloc.c

+15 −8
Original line number Original line Diff line number Diff line
@@ -5020,14 +5020,7 @@ static void setup_per_zone_lowmem_reserve(void) 
	calculate_totalreserve_pages();

	calculate_totalreserve_pages();

}

}





/**

static void __setup_per_zone_wmarks(void)

 * setup_per_zone_wmarks - called when min_free_kbytes changes

 * or when memory is hot-{added|removed}

 *

 * Ensures that the watermark[min,low,high] values for each zone are set

 * correctly with respect to min_free_kbytes.

 */

void setup_per_zone_wmarks(void)

{

{

	unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10);

	unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10);

	unsigned long lowmem_pages = 0;

	unsigned long lowmem_pages = 0;
@@ -5082,6 +5075,20 @@ void setup_per_zone_wmarks(void) 
	calculate_totalreserve_pages();

	calculate_totalreserve_pages();

}

}





/**

 * setup_per_zone_wmarks - called when min_free_kbytes changes

 * or when memory is hot-{added|removed}

 *

 * Ensures that the watermark[min,low,high] values for each zone are set

 * correctly with respect to min_free_kbytes.

 */

void setup_per_zone_wmarks(void)

{

	mutex_lock(&zonelists_mutex);

	__setup_per_zone_wmarks();

	mutex_unlock(&zonelists_mutex);

}



/*

/*

 * The inactive anon list should be small enough that the VM never has to

 * The inactive anon list should be small enough that the VM never has to

 * do too much work, but large enough that each inactive page has a chance

 * do too much work, but large enough that each inactive page has a chance