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 3D75C6B0005 for ; Sat, 16 Apr 2016 00:55:21 -0400 (EDT) Received: by mail-pf0-f199.google.com with SMTP id e190so222338132pfe.3 for ; Fri, 15 Apr 2016 21:55:21 -0700 (PDT) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id kq10si1143505pab.242.2016.04.15.21.55.20 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 15 Apr 2016 21:55:20 -0700 (PDT) Date: Fri, 15 Apr 2016 21:55:19 -0700 From: Andrew Morton Subject: Re: [PATCH 09/10] huge pagecache: mmap_sem is unlocked when truncation splits pmd Message-Id: <20160415215519.98f179c7418d4d2e9b316240@linux-foundation.org> In-Reply-To: <20160414173922.GE3120@linux.intel.com> References: <20160414173922.GE3120@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Matthew Wilcox Cc: Hugh Dickins , "Kirill A. Shutemov" , Andrea Arcangeli , Andres Lagar-Cavilla , Yang Shi , Ning Qu , David Rientjes , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Thu, 14 Apr 2016 13:39:22 -0400 Matthew Wilcox wrote: > 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? Wilco, thanks. -- 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