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 <mgorman@suse.de> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Tested-by: Barry Song <Baohua.Song@csr.com>
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@ -5020,14 +5020,7 @@ static void setup_per_zone_lowmem_reserve(void)
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calculate_totalreserve_pages();
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}
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/**
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* setup_per_zone_wmarks - called when min_free_kbytes changes
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* or when memory is hot-{added|removed}
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*
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* Ensures that the watermark[min,low,high] values for each zone are set
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* correctly with respect to min_free_kbytes.
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*/
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void setup_per_zone_wmarks(void)
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static void __setup_per_zone_wmarks(void)
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{
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unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10);
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unsigned long lowmem_pages = 0;
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@ -5082,6 +5075,20 @@ void setup_per_zone_wmarks(void)
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calculate_totalreserve_pages();
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}
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/**
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* setup_per_zone_wmarks - called when min_free_kbytes changes
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* or when memory is hot-{added|removed}
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*
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* Ensures that the watermark[min,low,high] values for each zone are set
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* correctly with respect to min_free_kbytes.
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*/
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void setup_per_zone_wmarks(void)
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{
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mutex_lock(&zonelists_mutex);
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__setup_per_zone_wmarks();
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mutex_unlock(&zonelists_mutex);
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}
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/*
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* The inactive anon list should be small enough that the VM never has to
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* do too much work, but large enough that each inactive page has a chance
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