From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D129BC46464 for ; Tue, 14 Aug 2018 20:32:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 65BAC21717 for ; Tue, 14 Aug 2018 20:32:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 65BAC21717 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728347AbeHNXVk (ORCPT ); Tue, 14 Aug 2018 19:21:40 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:60530 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726837AbeHNXVk (ORCPT ); Tue, 14 Aug 2018 19:21:40 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A42E04219DD3; Tue, 14 Aug 2018 20:32:46 +0000 (UTC) Received: from localhost (unknown [10.18.25.149]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7FECF2156712; Tue, 14 Aug 2018 20:32:46 +0000 (UTC) Date: Tue, 14 Aug 2018 16:32:46 -0400 From: Mike Snitzer To: xiao jin , Mikulas Patocka Cc: agk@redhat.com, dm-devel@redhat.com, linux-kernel@vger.kernel.org, yanmin.zhang@intel.com Subject: Re: dm-bufio: adjust the reserved buffer for dm-verify-target. Message-ID: <20180814203245.GA15636@redhat.com> References: <1533710457-6411-1-git-send-email-jin.xiao@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1533710457-6411-1-git-send-email-jin.xiao@intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Tue, 14 Aug 2018 20:32:46 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Tue, 14 Aug 2018 20:32:46 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'msnitzer@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 08 2018 at 2:40am -0400, xiao jin wrote: > We hit the BUG() report at include/linux/scatterlist.h:144! > The callback is as bellow: > => verity_work > => verity_hash_for_block > => verity_verify_level > => verity_hash > => verity_hash_update > => sg_init_one > => sg_set_buf > > More debug shows the root cause. When creating dufio client it > uses the __vmalloc() to allocate the buffer data for the reserved > dm_buffer. The buffer that allocated by the __vmalloc() is invalid > according to the __virt_addr_valid(). > > Mostly the reserved dm_buffer is not touched. But occasionally > it might fail to allocate the dm_buffer data when we try to > allocate in the __alloc_buffer_wait_no_callback(). Then it has > to take the reserved dm_buffer for usage. Finally it reports the > BUG() as virt_addr_valid() detects the buffer data address is invalid. > > The patch is to adjust the reserved buffer for dm-verity-target. We > allocated two dm_buffers into the reserved buffers list when creating > the buffer interface. The first dm_buffer in the reserved buffer list > is allocated by the __vmalloc(), it's not used after that. The second > dm_buffer in the reserved buffer list is allocated by the > __get_free_pages() which can be consumed after that. > > Signed-off-by: xiao jin > --- > drivers/md/dm-bufio.c | 4 ++-- > drivers/md/dm-verity-target.c | 2 +- > 2 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c > index dc385b7..3b7ca5e 100644 > --- a/drivers/md/dm-bufio.c > +++ b/drivers/md/dm-bufio.c > @@ -841,7 +841,7 @@ static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client > tried_noio_alloc = true; > } > > - if (!list_empty(&c->reserved_buffers)) { > + if (!c->need_reserved_buffers) { > b = list_entry(c->reserved_buffers.next, > struct dm_buffer, lru_list); > list_del(&b->lru_list); > @@ -1701,7 +1701,7 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign > goto bad; > } > > - while (c->need_reserved_buffers) { > + if (list_empty(&c->reserved_buffers)) { > struct dm_buffer *b = alloc_buffer(c, GFP_KERNEL); > > if (!b) { Point was to allocate N buffers (as accounted in c->need_reserved_buffers). This change just allocates a single one. Why? Your header isn't clear on this at all. > diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c > index 12decdbd7..40c66fc 100644 > --- a/drivers/md/dm-verity-target.c > +++ b/drivers/md/dm-verity-target.c > @@ -1107,7 +1107,7 @@ static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv) > v->hash_blocks = hash_position; > > v->bufio = dm_bufio_client_create(v->hash_dev->bdev, > - 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), > + 1 << v->hash_dev_block_bits, 2, sizeof(struct buffer_aux), > dm_bufio_alloc_callback, NULL); > if (IS_ERR(v->bufio)) { > ti->error = "Cannot initialize dm-bufio"; > -- > 2.7.4 > > -- > dm-devel mailing list > dm-devel@redhat.com > https://www.redhat.com/mailman/listinfo/dm-devel It isn't at all clear from my initial review that what you're doing makes any sense. Seems like you're just papering over bufio's use of !__virt_addr_valid() memory in unintuitive ways. Mikulas, can you see a better way forward? Mike