From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755912AbcA2MfT (ORCPT ); Fri, 29 Jan 2016 07:35:19 -0500 Received: from mga09.intel.com ([134.134.136.24]:10411 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754977AbcA2MfR (ORCPT ); Fri, 29 Jan 2016 07:35:17 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.22,364,1449561600"; d="scan'208,223";a="903805288" Date: Fri, 29 Jan 2016 15:35:11 +0300 From: "Kirill A. Shutemov" To: Dmitry Vyukov Cc: "Kirill A. Shutemov" , Vlastimil Babka , Doug Gilbert , Andrew Morton , David Rientjes , Naoya Horiguchi , Shiraz Hashim , "linux-mm@kvack.org" , LKML , Hugh Dickins , Sasha Levin , syzkaller , Kostya Serebryany , Alexander Potapenko , linux-scsi Subject: Re: mm: another VM_BUG_ON_PAGE(PageTail(page)) Message-ID: <20160129123511.GA146512@black.fi.intel.com> References: <20160128105136.GD2396@node.shutemov.name> <20160128114042.GE2396@node.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>From e20cd50a8f612dbc720d31d269e748215607a0b8 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Fri, 29 Jan 2016 14:55:40 +0300 Subject: [PATCH 1/2] mm: fix bogus VM_BUG_ON_PAGE() in isolate_lru_page() We don't care if there's a tail pages which is not on LRU. We are not going to isolate them anyway. Testcase: #include #include #include #include #include #define SIZE 0x2000 int foo; int main() { int fd; char *p; unsigned long mask = 2; fd = open("/dev/sg0", O_RDWR); p = mmap(NULL, SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0); /* Faultin pages */ foo = p[0] + p[0x1000]; mbind(p, SIZE, MPOL_BIND, &mask, 4, MPOL_MF_MOVE | MPOL_MF_STRICT); return 0; } MPOL_MF_STRICT makes queue_pages_test_walk() ignore !vma_megratable() and we try to queue such pages for migration. It's good question why we ignore !vma_megratable() for MPOL_MF_STRICT, but it's subject for a separate patch. Signed-off-by: Kirill A. Shutemov Reported-by: Dmitry Vyukov Fixes: bb5b8589767a ("mm: make sure isolate_lru_page() is never called for tail page") --- mm/vmscan.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index eb3dd37ccd7c..492fbe73420b 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1443,7 +1443,7 @@ int isolate_lru_page(struct page *page) int ret = -EBUSY; VM_BUG_ON_PAGE(!page_count(page), page); - VM_BUG_ON_PAGE(PageTail(page), page); + VM_BUG_ON_PAGE(PageLRU(page) && PageTail(page), page); if (PageLRU(page)) { struct zone *zone = page_zone(page); -- 2.7.0.rc3