Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751665Ab3F3Hu5 (ORCPT ); Sun, 30 Jun 2013 03:50:57 -0400 Received: from mail-ea0-f176.google.com ([209.85.215.176]:34379 "EHLO mail-ea0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751261Ab3F3Huz (ORCPT ); Sun, 30 Jun 2013 03:50:55 -0400 Message-ID: <1372578650.3301.305.camel@edumazet-glaptop> Subject: Re: kernel panic in skb_copy_bits From: Eric Dumazet To: Joe Jin Cc: Frank Blaschka , "David S. Miller" , "linux-kernel@vger.kernel.org" , "netdev@vger.kernel.org" , "zheng.x.li@oracle.com" , Xen Devel , Ian Campbell , Jan Beulich , Stefano Stabellini Date: Sun, 30 Jun 2013 00:50:50 -0700 In-Reply-To: <51CF7B31.8050408@oracle.com> References: <51CBAA48.3080802@oracle.com> <1372311118.3301.214.camel@edumazet-glaptop> <51CD0E67.4000008@oracle.com> <1372402340.3301.229.camel@edumazet-glaptop> <1372412262.3301.251.camel@edumazet-glaptop> <51CE1E19.3020108@oracle.com> <1372490428.3301.300.camel@edumazet-glaptop> <51CF7B31.8050408@oracle.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 716 Lines: 19 On Sun, 2013-06-30 at 08:26 +0800, Joe Jin wrote: > So far we suspected it caused by iscsi called sendpage(), and later page > be unmapped but still trying copy skb. We'll try to disable sg to see if > help or no. sendpage() should increment page refcounts for every page frag of an skb, therefore page should not be unmapped. Of course userland can either rewrite the content, or unmap() the page, but the underlying page cannot be freed as long skb is not freed. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/