From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id 328EC6B0005 for ; Thu, 14 Apr 2016 13:39:33 -0400 (EDT) Received: by mail-pf0-f199.google.com with SMTP id c20so141056287pfc.2 for ; Thu, 14 Apr 2016 10:39:33 -0700 (PDT) Received: from mga14.intel.com (mga14.intel.com. [192.55.52.115]) by mx.google.com with ESMTP id vx8si10640964pac.107.2016.04.14.10.39.32 for ; Thu, 14 Apr 2016 10:39:32 -0700 (PDT) Date: Thu, 14 Apr 2016 13:39:22 -0400 From: Matthew Wilcox Subject: Re: [PATCH 09/10] huge pagecache: mmap_sem is unlocked when truncation splits pmd Message-ID: <20160414173922.GE3120@linux.intel.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Hugh Dickins Cc: Andrew Morton , "Kirill A. Shutemov" , Andrea Arcangeli , Andres Lagar-Cavilla , Yang Shi , Ning Qu , David Rientjes , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Tue, Apr 05, 2016 at 01:55:23PM -0700, Hugh Dickins wrote: > zap_pmd_range()'s CONFIG_DEBUG_VM !rwsem_is_locked(&mmap_sem) BUG() > will be invalid with huge pagecache, in whatever way it is implemented: > truncation of a hugely-mapped file to an unhugely-aligned size would > easily hit it. We can reproduce this BUG() in the current Linus tree with DAX PMDs. Andrew, can you send this patch to Linus for inclusion in 4.7? Tested-by: Matthew Wilcox -- 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