From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f50.google.com (mail-pa0-f50.google.com [209.85.220.50]) by kanga.kvack.org (Postfix) with ESMTP id B00EA6B0038 for ; Sun, 22 Mar 2015 19:57:46 -0400 (EDT) Received: by pagj4 with SMTP id j4so81783214pag.2 for ; Sun, 22 Mar 2015 16:57:46 -0700 (PDT) Received: from shards.monkeyblade.net (shards.monkeyblade.net. [2001:4f8:3:36:211:85ff:fe63:a549]) by mx.google.com with ESMTP id pd3si19096445pdb.208.2015.03.22.16.57.45 for ; Sun, 22 Mar 2015 16:57:45 -0700 (PDT) Date: Sun, 22 Mar 2015 19:57:43 -0400 (EDT) Message-Id: <20150322.195743.1225936659717870427.davem@davemloft.net> Subject: Re: 4.0.0-rc4: panic in free_block From: David Miller In-Reply-To: References: <20150322.182311.109269221031797359.davem@davemloft.net> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: torvalds@linux-foundation.org Cc: david.ahern@oracle.com, sparclinux@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org From: Linus Torvalds Date: Sun, 22 Mar 2015 16:49:51 -0700 > On Sun, Mar 22, 2015 at 3:23 PM, David Miller wrote: >> >> Yes, using VIS how we do is alright, and in fact I did an audit of >> this about 1 year ago. This is another one of those "if this is >> wrong, so much stuff would break" > > Maybe. But it does seem like Bob Picco has narrowed it down to memmove(). > > It also bothers me enormously - and perhaps unreasonably - how that > memcpy code has memory barriers in it. I can see _zero_ reason for a > memory barrier inside a memcpy, unless the memcpy does something that > isn't valid to begin with. Are the VIS operatiosn perhaps using some > kind of non-temporal form that doesn't follow the TSO rules? Kind of > like the "movnt" that Intel has? The special cache line clearing stores (the ASI_BLK_INIT_QUAD_LDD_P stuff) do not adhere to the memory model. I had elided the memory barriers originally, but it caused memory corruption. So yes, this is similar to the 'movnt' situation. -- 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