From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qc0-f173.google.com (mail-qc0-f173.google.com [209.85.216.173]) by kanga.kvack.org (Postfix) with ESMTP id 4C6F36B0035 for ; Fri, 25 Apr 2014 14:42:15 -0400 (EDT) Received: by mail-qc0-f173.google.com with SMTP id r5so4321257qcx.4 for ; Fri, 25 Apr 2014 11:42:14 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTP id v39si4320965qge.179.2014.04.25.11.42.14 for ; Fri, 25 Apr 2014 11:42:14 -0700 (PDT) Date: Fri, 25 Apr 2014 14:41:47 -0400 From: Rik van Riel Subject: [PATCH] mm,numa: remove BUG_ON in __handle_mm_fault Message-ID: <20140425144147.679a7608@annuminas.surriel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, lwoodman@redhat.com, peterz@infradead.org, mgorman@suse.de, dave.hansen@intel.com, sunil.k.pandey@intel.com Changing PTEs and PMDs to pte_numa & pmd_numa is done with the mmap_sem held for reading, which means a pmd can be instantiated and/or turned into a numa one while __handle_mm_fault is examining the value of orig_pmd. If that happens, __handle_mm_fault should just return and let the page fault retry, instead of throwing an oops. Signed-off-by: Rik van Riel Reported-by: Sunil Pandey --- mm/memory.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index d0f0bef..9edccb2 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3900,8 +3900,9 @@ static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, } } - /* THP should already have been handled */ - BUG_ON(pmd_numa(*pmd)); + /* The PMD became NUMA while we examined orig_pmd. Return & retry */ + if (pmd_numa(*pmd)) + return 0; /* * Use __pte_alloc instead of pte_alloc_map, because we can't -- 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: email@kvack.org