From cfd3da1e49bb95c355c01c0f502d657deb3d34a4 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Mon, 25 Apr 2011 21:36:42 +0000 Subject: 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: Mel Gorman Signed-off-by: Marek Szyprowski Reviewed-by: KAMEZAWA Hiroyuki Tested-by: Barry Song diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 116c087..8be37bc 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5020,14 +5020,7 @@ static void setup_per_zone_lowmem_reserve(void) 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) +static void __setup_per_zone_wmarks(void) { unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10); unsigned long lowmem_pages = 0; @@ -5082,6 +5075,20 @@ void setup_per_zone_wmarks(void) 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 * do too much work, but large enough that each inactive page has a chance -- cgit v0.10.2