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Subject[PATCH -mmotm 01/30] mm: serialize access to min_free_kbytes
From bc55bacd6bcc0f8a69c0d7e0d554c78237233e07 Mon Sep 17 00:00:00 2001
From: Xiaotian Feng <dfeng@redhat.com>
Date: Mon, 12 Jul 2010 17:58:34 +0800
Subject: [PATCH 01/30] mm: serialize access to min_free_kbytes

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 <a.p.zijlstra@chello.nl>
Signed-off-by: Suresh Jayaraman <sjayaraman@suse.de>
Signed-off-by: Xiaotian Feng <dfeng@redhat.com>
---
mm/page_alloc.c | 16 +++++++++++++---
1 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 50a6d10..ebf0af7 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -165,6 +165,7 @@ static char * const zone_names[MAX_NR_ZONES] = {
"Movable",
};

+static DEFINE_SPINLOCK(min_free_lock);
int min_free_kbytes = 1024;

static unsigned long __meminitdata nr_kernel_pages;
@@ -4839,13 +4840,13 @@ static void setup_per_zone_lowmem_reserve(void)
}

/**
- * 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;
@@ -4943,6 +4944,15 @@ static void __init setup_per_zone_inactive_ratio(void)
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.
*
@@ -4978,7 +4988,7 @@ static int __init init_per_zone_wmark_min(void)
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;
--
1.7.1.1


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