From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758303AbaD2Tgs (ORCPT ); Tue, 29 Apr 2014 15:36:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:11364 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751878AbaD2Tgr (ORCPT ); Tue, 29 Apr 2014 15:36:47 -0400 Date: Tue, 29 Apr 2014 15:36:15 -0400 From: Rik van Riel To: n-horiguchi@ah.jp.nec.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, lwoodman@redhat.com, peterz@infradead.org, mgorman@suse.de, dave.hansen@intel.com, sunil.k.pandey@intel.com Subject: [PATCH -v2] mm,numa: remove BUG_ON in __handle_mm_fault Message-ID: <20140429153615.2d72098e@annuminas.surriel.com> In-Reply-To: <1398799576-9pfzypnu@n-horiguchi@ah.jp.nec.com> References: <20140425144147.679a7608@annuminas.surriel.com> <1398799576-9pfzypnu@n-horiguchi@ah.jp.nec.com> Organization: Red Hat, Inc. MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Peter pointed out we can do this slightly simpler, since we already have a test for pmd_trans_huge(*pmd) below... ---8<--- 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 turned into a numa one while __handle_mm_fault is examining the value of old_pmd. If that happens, __handle_mm_fault should just return and let the page fault retry, instead of throwing an oops. This is handled by the test for pmd_trans_huge(*pmd) below. Signed-off-by: Rik van Riel Reviewed-by: Naoya Horiguchi Reported-by: Sunil Pandey Cc: stable@kernel.org --- mm/memory.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index d0f0bef..9c2dc65 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3900,9 +3900,6 @@ 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)); - /* * Use __pte_alloc instead of pte_alloc_map, because we can't * run pte_offset_map on the pmd, if an huge pmd could