From patchwork Fri Jan 17 14:39:55 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?b?SsO8cmdlbiBHcm/Dnw==?= X-Patchwork-Id: 11339363 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 095401820 for ; Fri, 17 Jan 2020 14:41:26 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E3EBC2073A for ; Fri, 17 Jan 2020 14:41:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E3EBC2073A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1isSnD-0003B7-Ha; Fri, 17 Jan 2020 14:40:11 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1isSnB-0003A0-Sy for xen-devel@lists.xenproject.org; Fri, 17 Jan 2020 14:40:09 +0000 X-Inumbo-ID: 3cce1218-3937-11ea-aecd-bc764e2007e4 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 3cce1218-3937-11ea-aecd-bc764e2007e4; Fri, 17 Jan 2020 14:39:59 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 59B93B17A; Fri, 17 Jan 2020 14:39:58 +0000 (UTC) From: Juergen Gross To: xen-devel@lists.xenproject.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Date: Fri, 17 Jan 2020 15:39:55 +0100 Message-Id: <20200117143955.18892-1-jgross@suse.com> X-Mailer: git-send-email 2.16.4 Subject: [Xen-devel] [PATCH] xen/blkfront: limit allocated memory size to actual use case X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Juergen Gross , Jens Axboe , Stefano Stabellini , Konrad Rzeszutek Wilk , Boris Ostrovsky , =?utf-8?q?Roger_Pau_Monn?= =?utf-8?q?=C3=A9?= MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" Today the Xen blkfront driver allocates memory for one struct blkfront_ring_info for each communication ring. This structure is statically sized for the maximum supported configuration resulting in a size of more than 90 kB. As the main size contributor is one array inside the struct, the memory allocation can easily be limited by moving this array to be the last structure element and to allocate only the memory for the actually needed array size. Signed-off-by: Juergen Gross Acked-by: Roger Pau Monné --- drivers/block/xen-blkfront.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index c02be06c5299..61491167da19 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -151,9 +151,6 @@ MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the #define BLK_RING_SIZE(info) \ __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages) -#define BLK_MAX_RING_SIZE \ - __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * XENBUS_MAX_RING_GRANTS) - /* * ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19 * characters are enough. Define to 20 to keep consistent with backend. @@ -177,12 +174,12 @@ struct blkfront_ring_info { unsigned int evtchn, irq; struct work_struct work; struct gnttab_free_callback callback; - struct blk_shadow shadow[BLK_MAX_RING_SIZE]; struct list_head indirect_pages; struct list_head grants; unsigned int persistent_gnts_c; unsigned long shadow_free; struct blkfront_info *dev_info; + struct blk_shadow shadow[]; }; /* @@ -1915,7 +1912,8 @@ static int negotiate_mq(struct blkfront_info *info) info->nr_rings = 1; info->rinfo = kvcalloc(info->nr_rings, - sizeof(struct blkfront_ring_info), + struct_size(info->rinfo, shadow, + BLK_RING_SIZE(info)), GFP_KERNEL); if (!info->rinfo) { xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");