From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753760AbeE3Li3 (ORCPT ); Wed, 30 May 2018 07:38:29 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:60753 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752144AbeE3LHB (ORCPT ); Wed, 30 May 2018 07:07:01 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Shaohua Li" , "chenjie" , "Rik van Riel" , "Mel Gorman" , "Michal Hocko" , "Carsten Otte" , "Kirill A. Shutemov" , "Linus Torvalds" , "Minchan Kim" , "Miao Xie" , "Mike Rapoport" , "David Rientjes" , "guoxuenan" , "Andrea Arcangeli" , "Dan Williams" , "zhangyi (F)" , "Anshuman Khandual" Date: Wed, 30 May 2018 11:52:41 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 002/153] mm/madvise.c: fix madvise() infinite loop under special circumstances In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.102-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: chenjie commit 6ea8d958a2c95a1d514015d4e29ba21a8c0a1a91 upstream. MADVISE_WILLNEED has always been a noop for DAX (formerly XIP) mappings. Unfortunately madvise_willneed() doesn't communicate this information properly to the generic madvise syscall implementation. The calling convention is quite subtle there. madvise_vma() is supposed to either return an error or update &prev otherwise the main loop will never advance to the next vma and it will keep looping for ever without a way to get out of the kernel. It seems this has been broken since introduction. Nobody has noticed because nobody seems to be using MADVISE_WILLNEED on these DAX mappings. [mhocko@suse.com: rewrite changelog] Link: http://lkml.kernel.org/r/20171127115318.911-1-guoxuenan@huawei.com Fixes: fe77ba6f4f97 ("[PATCH] xip: madvice/fadvice: execute in place") Signed-off-by: chenjie Signed-off-by: guoxuenan Acked-by: Michal Hocko Cc: Minchan Kim Cc: zhangyi (F) Cc: Miao Xie Cc: Mike Rapoport Cc: Shaohua Li Cc: Andrea Arcangeli Cc: Mel Gorman Cc: Kirill A. Shutemov Cc: David Rientjes Cc: Anshuman Khandual Cc: Rik van Riel Cc: Carsten Otte Cc: Dan Williams Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- --- a/mm/madvise.c +++ b/mm/madvise.c @@ -128,6 +128,7 @@ static long madvise_willneed(struct vm_a { struct file *file = vma->vm_file; + *prev = vma; if (!file) return -EBADF; @@ -136,7 +137,6 @@ static long madvise_willneed(struct vm_a return 0; } - *prev = vma; start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; if (end > vma->vm_end) end = vma->vm_end;