Subject: + mm-use-a-dedicated-lock-to-protect-totalram_pages-and-zone-managed_pages.patch added to -mm tree
To: liuj97@xxxxxxxxx,arnd@xxxxxxxx,catalin.marinas@xxxxxxx,cmetcalf@xxxxxxxxxx,dhowells@xxxxxxxxxx,geert@xxxxxxxxxxxxxx,hpa@xxxxxxxxx,isimatu.yasuaki@xxxxxxxxxxxxxx,jeremy@xxxxxxxx,jiang.liu@xxxxxxxxxx,js1304@xxxxxxxxx,kamezawa.hiroyu@xxxxxxxxxxxxxx,konrad.wilk@xxxxxxxxxx,m.szyprowski@xxxxxxxxxxx,mel@xxxxxxxxx,minchan@xxxxxxxxxx,mingo@xxxxxxxxxx,mst@xxxxxxxxxx,riel@xxxxxxxxxx,rmk@xxxxxxxxxxxxxxxx,rusty@xxxxxxxxxxxxxxx,sworddragon2@xxxxxxx,tangchen@xxxxxxxxxxxxxx,tglx@xxxxxxxxxxxxx,tj@xxxxxxxxxx,walken@xxxxxxxxxx,wency@xxxxxxxxxxxxxx,will.deacon@xxxxxxx,wujianguo@xxxxxxxxxx,yinghai@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Thu, 30 May 2013 15:17:02 -0700
The patch titled
Subject: mm: use a dedicated lock to protect totalram_pages and zone->managed_pages
has been added to the -mm tree. Its filename is
mm-use-a-dedicated-lock-to-protect-totalram_pages-and-zone-managed_pages.patch
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------------------------------------------------------
From: Jiang Liu <liuj97@xxxxxxxxx>
Subject: mm: use a dedicated lock to protect totalram_pages and zone->managed_pages
Currently lock_memory_hotplug()/unlock_memory_hotplug() are used to
protect totalram_pages and zone->managed_pages. Other than the memory
hotplug driver, totalram_pages and zone->managed_pages may also be
modified at runtime by other drivers, such as Xen balloon, virtio_balloon
etc. For those cases, memory hotplug lock is a little too heavy, so
introduce a dedicated lock to protect totalram_pages and
zone->managed_pages.
Now we have a simplified locking rules totalram_pages and
zone->managed_pages as:
1) no locking for read accesses because they are unsigned long.
2) no locking for write accesses at boot time in single-threaded context.
3) serialize write accesses at runtime by acquiring the dedicated
managed_page_count_lock.
Also adjust zone->managed_pages when freeing reserved pages into the buddy
system, to keep totalram_pages and zone->managed_pages in consistence.
Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: Michel Lespinasse <walken@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
Cc: <sworddragon2@xxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Chris Metcalf <cmetcalf@xxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Cc: Jianguo Wu <wujianguo@xxxxxxxxxx>
Cc: Joonsoo Kim <js1304@xxxxxxxxx>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Tang Chen <tangchen@xxxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Wen Congyang <wency@xxxxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: Russell King <rmk@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm.h | 6 ++----
include/linux/mmzone.h | 14 ++++++++++----
mm/page_alloc.c | 12 ++++++++++++
3 files changed, 24 insertions(+), 8 deletions(-)
diff -puN include/linux/mm.h~mm-use-a-dedicated-lock-to-protect-totalram_pages-and-zone-managed_pages include/linux/mm.h
--- a/include/linux/mm.h~mm-use-a-dedicated-lock-to-protect-totalram_pages-and-zone-managed_pages
+++ a/include/linux/mm.h
@@ -1313,6 +1313,7 @@ extern void free_initmem(void);
*/
extern unsigned long free_reserved_area(void *start, void *end,
int poison, char *s);
+
#ifdef CONFIG_HIGHMEM
/*
* Free a highmem page into the buddy system, adjusting totalhigh_pages
@@ -1321,10 +1322,7 @@ extern unsigned long free_reserved_area(
extern void free_highmem_page(struct page *page);
#endif
-static inline void adjust_managed_page_count(struct page *page, long count)
-{
- totalram_pages += count;
-}
+extern void adjust_managed_page_count(struct page *page, long count);
/* Free the reserved page into the buddy system, so it gets managed. */
static inline void __free_reserved_page(struct page *page)
diff -puN include/linux/mmzone.h~mm-use-a-dedicated-lock-to-protect-totalram_pages-and-zone-managed_pages include/linux/mmzone.h
--- a/include/linux/mmzone.h~mm-use-a-dedicated-lock-to-protect-totalram_pages-and-zone-managed_pages
+++ a/include/linux/mmzone.h
@@ -474,10 +474,16 @@ struct zone {
* frequently read in proximity to zone->lock. It's good to
* give them a chance of being in the same cacheline.
*
- * Write access to present_pages and managed_pages at runtime should
- * be protected by lock_memory_hotplug()/unlock_memory_hotplug().
- * Any reader who can't tolerant drift of present_pages and
- * managed_pages should hold memory hotplug lock to get a stable value.
+ * Write access to present_pages at runtime should be protected by
+ * lock_memory_hotplug()/unlock_memory_hotplug(). Any reader who can't
+ * tolerant drift of present_pages should hold memory hotplug lock to
+ * get a stable value.
+ *
+ * Read access to managed_pages should be safe because it's unsigned
+ * long. Write access to zone->managed_pages and totalram_pages are
+ * protected by managed_page_count_lock at runtime. Idealy only
+ * adjust_managed_page_count() should be used instead of directly
+ * touching zone->managed_pages and totalram_pages.
*/
unsigned long spanned_pages;
unsigned long present_pages;
diff -puN mm/page_alloc.c~mm-use-a-dedicated-lock-to-protect-totalram_pages-and-zone-managed_pages mm/page_alloc.c
--- a/mm/page_alloc.c~mm-use-a-dedicated-lock-to-protect-totalram_pages-and-zone-managed_pages
+++ a/mm/page_alloc.c
@@ -103,6 +103,9 @@ nodemask_t node_states[NR_NODE_STATES] _
};
EXPORT_SYMBOL(node_states);
+/* Protect totalram_pages and zone->managed_pages */
+static DEFINE_SPINLOCK(managed_page_count_lock);
+
unsigned long totalram_pages __read_mostly;
unsigned long totalreserve_pages __read_mostly;
/*
@@ -5218,6 +5221,15 @@ early_param("movablecore", cmdline_parse
#endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
+void adjust_managed_page_count(struct page *page, long count)
+{
+ spin_lock(&managed_page_count_lock);
+ page_zone(page)->managed_pages += count;
+ totalram_pages += count;
+ spin_unlock(&managed_page_count_lock);
+}
+EXPORT_SYMBOL(adjust_managed_page_count);
+
unsigned long free_reserved_area(void *start, void *end, int poison, char *s)
{
void *pos;
_
Patches currently in -mm which might be from liuj97@xxxxxxxxx are
linux-next.patch
mm-change-signature-of-free_reserved_area-to-fix-building-warnings.patch
mm-enhance-free_reserved_area-to-support-poisoning-memory-with-zero.patch
mm-arm64-kill-poison_init_mem.patch
mm-x86-use-free_reserved_area-to-simplify-code.patch
mm-tile-use-common-help-functions-to-free-reserved-pages.patch
mm-fix-some-trivial-typos-in-comments.patch
mm-use-managed_pages-to-calculate-default-zonelist-order.patch
mm-accurately-calculate-zone-managed_pages-for-highmem-zones.patch
mm-use-a-dedicated-lock-to-protect-totalram_pages-and-zone-managed_pages.patch
mm-make-__free_pages_bootmem-only-available-at-boot-time.patch
mm-correctly-update-zone-managed_pages.patch
mm-correctly-update-zone-managed_pages-fix.patch
mm-concentrate-modification-of-totalram_pages-into-the-mm-core.patch
mm-report-available-pages-as-memtotal-for-each-numa-node.patch
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