Commit cfd19c5a authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds
Browse files

mm: only set page->pfmemalloc when ALLOC_NO_WATERMARKS was used 



__alloc_pages_slowpath() is called when the number of free pages is below
the low watermark.  If the caller is entitled to use ALLOC_NO_WATERMARKS
then the page will be marked page->pfmemalloc.  This protects more pages
than are strictly necessary as we only need to protect pages allocated
below the min watermark (the pfmemalloc reserves).

This patch only sets page->pfmemalloc when ALLOC_NO_WATERMARKS was
required to allocate the page.

[rientjes@google.com: David noticed the problem during review]
Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 907aed48

mm/page_alloc.c

+14 −13
Original line number Diff line number Diff line
@@ -2116,8 +2116,8 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order, 


		page = get_page_from_freelist(gfp_mask, nodemask,

				order, zonelist, high_zoneidx,

				alloc_flags, preferred_zone,

				migratetype);

				alloc_flags & ~ALLOC_NO_WATERMARKS,

				preferred_zone, migratetype);

		if (page) {

			preferred_zone->compact_considered = 0;

			preferred_zone->compact_defer_shift = 0;
@@ -2209,8 +2209,8 @@ __alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order, 
retry:

	page = get_page_from_freelist(gfp_mask, nodemask, order,

					zonelist, high_zoneidx,

					alloc_flags, preferred_zone,

					migratetype);

					alloc_flags & ~ALLOC_NO_WATERMARKS,

					preferred_zone, migratetype);



	/*

	 * If an allocation failed after direct reclaim, it could be because
@@ -2381,9 +2381,18 @@ rebalance: 
		page = __alloc_pages_high_priority(gfp_mask, order,

				zonelist, high_zoneidx, nodemask,

				preferred_zone, migratetype);

		if (page)

		if (page) {

			/*

			 * page->pfmemalloc is set when ALLOC_NO_WATERMARKS was

			 * necessary to allocate the page. The expectation is

			 * that the caller is taking steps that will free more

			 * memory. The caller should avoid the page being used

			 * for !PFMEMALLOC purposes.

			 */

			page->pfmemalloc = true;

			goto got_pg;

		}

	}



	/* Atomic allocations - we can't balance anything */

	if (!wait)
@@ -2499,14 +2508,6 @@ nopage: 
	warn_alloc_failed(gfp_mask, order, NULL);

	return page;

got_pg:

	/*

	 * page->pfmemalloc is set when the caller had PFMEMALLOC set, is

	 * been OOM killed or specified __GFP_MEMALLOC. The expectation is

	 * that the caller is taking steps that will free more memory. The

	 * caller should avoid the page being used for !PFMEMALLOC purposes.

	 */

	page->pfmemalloc = !!(alloc_flags & ALLOC_NO_WATERMARKS);



	if (kmemcheck_enabled)

		kmemcheck_pagealloc_alloc(page, order, gfp_mask);

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