Commit d34c5fa0 authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds

mm: page_alloc: only check the zone id check if pages are buddies

A node/zone index is used to check if pages are compatible for merging
but this happens unconditionally even if the buddy page is not free. Defer
the calculation as long as possible. Ideally we would check the zone boundary
but nodes can overlap.
Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarRik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 664eedde
......@@ -509,16 +509,26 @@ static inline int page_is_buddy(struct page *page, struct page *buddy,
if (!pfn_valid_within(page_to_pfn(buddy)))
return 0;
if (page_zone_id(page) != page_zone_id(buddy))
return 0;
if (page_is_guard(buddy) && page_order(buddy) == order) {
VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
if (page_zone_id(page) != page_zone_id(buddy))
return 0;
return 1;
}
if (PageBuddy(buddy) && page_order(buddy) == order) {
VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
/*
* zone check is done late to avoid uselessly
* calculating zone/node ids for pages that could
* never merge.
*/
if (page_zone_id(page) != page_zone_id(buddy))
return 0;
return 1;
}
return 0;
......
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