Messages in this thread Patch in this message | | | Date | Fri, 15 Jun 2012 16:19:12 +0900 | From | Minchan Kim <> | Subject | Re: [PATCH] mm: clear pages_scanned only if draining a pcp adds pages to the buddy allocator again |
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On 06/15/2012 01:16 AM, kosaki.motohiro@gmail.com wrote:
> From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> > > commit 2ff754fa8f (mm: clear pages_scanned only if draining a pcp adds pages > to the buddy allocator again) fixed one free_pcppages_bulk() misuse. But two > another miuse still exist. > > This patch fixes it. > > Cc: David Rientjes <rientjes@google.com> > Cc: Mel Gorman <mel@csn.ul.ie> > Cc: Johannes Weiner <hannes@cmpxchg.org> > Cc: Minchan Kim <minchan.kim@gmail.com> > Cc: Wu Fengguang <fengguang.wu@intel.com> > Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> > Cc: Rik van Riel <riel@redhat.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Just nitpick. Personally, I want to fix it follwing as It's more simple and reduce vulnerable error in future.
If you mind, go ahead with your version. I am not against with it, either.
barrios@bbox:~/linux-next$ git diff diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 4403009..a32ac56 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -637,6 +637,12 @@ static void free_pcppages_bulk(struct zone *zone, int count, int batch_free = 0; int to_free = count; + /* + * Let's avoid unnecessary reset of pages_scanned. + */ + if (!count) + return; + spin_lock(&zone->lock); zone->all_unreclaimable = 0; zone->pages_scanned = 0; @@ -1175,6 +1181,7 @@ static void drain_pages(unsigned int cpu) { unsigned long flags; struct zone *zone; + int to_drain; for_each_populated_zone(zone) { struct per_cpu_pageset *pset; @@ -1184,10 +1191,9 @@ static void drain_pages(unsigned int cpu) pset = per_cpu_ptr(zone->pageset, cpu); pcp = &pset->pcp; - if (pcp->count) { - free_pcppages_bulk(zone, pcp->count, pcp); - pcp->count = 0; - } + to_drain = pcp->count; + free_pcppages_bulk(zone, to_drain, pcp); + pcp->count -= to_drain; local_irq_restore(flags); } } -- Kind regards, Minchan Kim
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