From: Peter Zijlstra Subject: [PATCH 01/31] mm: serialize access to min_free_kbytes Patch-mainline: not yet There is a small race between the procfs caller and the memory hotplug caller of setup_per_zone_wmarks(). Not a big deal, but the next patch will add yet another caller. Time to close the gap. Signed-off-by: Peter Zijlstra Signed-off-by: Suresh Jayaraman --- mm/page_alloc.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -148,6 +148,7 @@ static char * const zone_names[MAX_NR_ZO "Movable", }; +static DEFINE_SPINLOCK(min_free_lock); int min_free_kbytes = 1024; static unsigned long __meminitdata nr_kernel_pages; @@ -4609,13 +4610,13 @@ static void setup_per_zone_lowmem_reserv } /** - * setup_per_zone_wmarks - called when min_free_kbytes changes + * __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; @@ -4713,6 +4714,15 @@ static void __init setup_per_zone_inacti calculate_zone_inactive_ratio(zone); } +void setup_per_zone_wmarks(void) +{ + unsigned long flags; + + spin_lock_irqsave(&min_free_lock, flags); + __setup_per_zone_wmarks(); + spin_unlock_irqrestore(&min_free_lock, flags); +} + /* * Initialise min_free_kbytes. * @@ -4748,7 +4758,7 @@ static int __init init_per_zone_wmark_mi min_free_kbytes = 128; if (min_free_kbytes > 65536) min_free_kbytes = 65536; - setup_per_zone_wmarks(); + __setup_per_zone_wmarks(); setup_per_zone_lowmem_reserve(); setup_per_zone_inactive_ratio(); return 0;