From c3a489cac38d43ea6dc4ac240473b44b46deecf7 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Wed, 18 Dec 2013 17:08:38 -0800 Subject: [PATCH] mm: numa: ensure anon_vma is locked to prevent parallel THP splits The anon_vma lock prevents parallel THP splits and any associated complexity that arises when handling splits during THP migration. This patch checks if the lock was successfully acquired and bails from THP migration if it failed for any reason. Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel Cc: Alex Thorlton Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/huge_memory.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 420826e..dbafffa 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1359,6 +1359,13 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, goto out_unlock; } + /* Bail if we fail to protect against THP splits for any reason */ + if (unlikely(!anon_vma)) { + put_page(page); + page_nid = -1; + goto clear_pmdnuma; + } + /* * Migrate the THP to the requested node, returns with page unlocked * and pmd_numa cleared. -- 2.7.4