From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756585AbbJUV5A (ORCPT ); Wed, 21 Oct 2015 17:57:00 -0400 Received: from mga09.intel.com ([134.134.136.24]:28700 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756476AbbJUV46 (ORCPT ); Wed, 21 Oct 2015 17:56:58 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,179,1444719600"; d="scan'208";a="669104866" Subject: [PATCH] mm, hugetlbfs: Fix new warning in fault-time huge page allocation To: dave@sr71.net Cc: kirill.shutemov@linux.intel.com, akpm@linux-foundation.org, n-horiguchi@ah.jp.nec.com, mike.kravetz@oracle.com, hillf.zj@alibaba-inc.com, rientjes@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, dave.hansen@linux.intel.com From: Dave Hansen Date: Wed, 21 Oct 2015 14:56:58 -0700 Message-Id: <20151021215658.ABDE5545@viggo.jf.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dave Hansen Kirill reported that he hit: >> + if (vma || addr) { >> + WARN_ON_ONCE(!addr || addr == -1); > > Trinity triggered the WARN for me: This was just a dumb mistake. I put the WARN_ON() in and planned to have addr=0 mean "use nid". But, I realized pretty quickly that addr=0 _is_ a valid place to fault. So I made it addr=-1 in __alloc_buddy_huge_page_no_mpol(), but I did not fix up the WARN_ON(). So hitting the warning in this case was harmless. But, fix up the warning condition. Cc: Kirill A. Shutemov Cc: Andrew Morton Cc: Naoya Horiguchi Cc: Mike Kravetz Cc: Hillf Danton Cc: David Rientjes Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Dave Hansen --- b/mm/hugetlb.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff -puN mm/hugetlb.c~hugetlbfs-fix-warn mm/hugetlb.c --- a/mm/hugetlb.c~hugetlbfs-fix-warn 2015-10-21 14:40:15.809961389 -0700 +++ b/mm/hugetlb.c 2015-10-21 14:40:15.814961616 -0700 @@ -1520,8 +1520,14 @@ static struct page *__alloc_buddy_huge_p if (hstate_is_gigantic(h)) return NULL; - if (vma || addr) { - VM_WARN_ON_ONCE(!addr || addr == -1); + /* + * Make sure that anyone specifying 'nid' is not also + * specifying a VMA. This makes sure the caller is + * picking _one_ of the modes with which we can call this + * function, not both. + */ + if (vma || (addr != -1)) { + VM_WARN_ON_ONCE(addr == -1); VM_WARN_ON_ONCE(nid != NUMA_NO_NODE); } /* _