Re: [PATCH] mm: clear pages_scanned only if draining a pcp adds pages to the buddy allocator again
From: Minchan Kim <minchan@kernel.org>
Date: 2012-06-15 07:19:09
Also in:
lkml
Subsystem:
memory management, memory management - page allocator, the rest · Maintainers:
Andrew Morton, Vlastimil Babka, Linus Torvalds
On 06/15/2012 01:16 AM, kosaki.motohiro@gmail.com wrote:
From: KOSAKI Motohiro <redacted> 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 <redacted> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <redacted> Cc: Wu Fengguang <redacted> Cc: KAMEZAWA Hiroyuki <redacted> Cc: Rik van Riel <redacted> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: KOSAKI Motohiro <redacted>
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
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>