From patchwork Tue Oct 21 10:58:19 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dheeraj Jamwal X-Patchwork-Id: 5122321 Return-Path: X-Original-To: patchwork-ltsi-dev@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 4A3CD9F349 for ; Tue, 21 Oct 2014 12:08:06 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 6CED020109 for ; Tue, 21 Oct 2014 12:08:05 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 63626200E0 for ; Tue, 21 Oct 2014 12:08:01 +0000 (UTC) Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 93BAC147B; Tue, 21 Oct 2014 11:14:26 +0000 (UTC) X-Original-To: ltsi-dev@lists.linuxfoundation.org Delivered-To: ltsi-dev@mail.linuxfoundation.org Received: from smtp2.linuxfoundation.org (smtp2.linux-foundation.org [172.17.192.36]) by mail.linuxfoundation.org (Postfix) with ESMTPS id F346D13E1 for ; Tue, 21 Oct 2014 11:14:17 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by smtp2.linuxfoundation.org (Postfix) with ESMTP id 7B8411DCCA for ; Tue, 21 Oct 2014 11:14:17 +0000 (UTC) Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga101.fm.intel.com with ESMTP; 21 Oct 2014 04:14:17 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.04,761,1406617200"; d="scan'208";a="617800970" Received: from ubuntu-desktop.png.intel.com ([10.221.122.25]) by fmsmga002.fm.intel.com with ESMTP; 21 Oct 2014 04:14:16 -0700 From: Dheeraj Jamwal To: ltsi-dev@lists.linuxfoundation.org Date: Tue, 21 Oct 2014 18:58:19 +0800 Message-Id: <1413889294-31328-900-git-send-email-dheerajx.s.jamwal@intel.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1413889294-31328-1-git-send-email-dheerajx.s.jamwal@intel.com> References: <1413889294-31328-1-git-send-email-dheerajx.s.jamwal@intel.com> X-Spam-Status: No, score=-5.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org Subject: [LTSI-dev] [PATCH 0899/1094] drm/gem: replace misleading comment X-BeenThere: ltsi-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: "A list to discuss patches, development, and other things related to the LTSI project" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: ltsi-dev-bounces@lists.linuxfoundation.org Errors-To: ltsi-dev-bounces@lists.linuxfoundation.org X-Virus-Scanned: ClamAV using ClamSMTP From: David Herrmann shmem supports page-relocations during swapin since quite some time. It was implemented in: commit bde05d1ccd512696b09db9dd2e5f33ad19152605 Author: Hugh Dickins Date: Tue May 29 15:06:38 2012 -0700 shmem: replace page if mapping excludes its zone The gem-comment about wrongly placed DMA32 pages is no longer valid. Replace it with a proper comment but keep the BUG_ON() to verify correct shmem behavior. Signed-off-by: David Herrmann Reviewed-by: Daniel Vetter Signed-off-by: Dave Airlie (cherry picked from commit 2123000b01792e182fc4122fdb612ed641f3385e) Signed-off-by: Dheeraj Jamwal --- drivers/gpu/drm/drm_gem.c | 19 ++++--------------- 1 file changed, 4 insertions(+), 15 deletions(-) diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index 2136052..4e25fa2 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -474,21 +474,10 @@ struct page **drm_gem_get_pages(struct drm_gem_object *obj, gfp_t gfpmask) goto fail; pages[i] = p; - /* There is a hypothetical issue w/ drivers that require - * buffer memory in the low 4GB.. if the pages are un- - * pinned, and swapped out, they can end up swapped back - * in above 4GB. If pages are already in memory, then - * shmem_read_mapping_page_gfp will ignore the gfpmask, - * even if the already in-memory page disobeys the mask. - * - * It is only a theoretical issue today, because none of - * the devices with this limitation can be populated with - * enough memory to trigger the issue. But this BUG_ON() - * is here as a reminder in case the problem with - * shmem_read_mapping_page_gfp() isn't solved by the time - * it does become a real issue. - * - * See this thread: http://lkml.org/lkml/2011/7/11/238 + /* Make sure shmem keeps __GFP_DMA32 allocated pages in the + * correct region during swapin. Note that this requires + * __GFP_DMA32 to be set in mapping_gfp_mask(inode->i_mapping) + * so shmem can relocate pages during swapin if required. */ BUG_ON((gfpmask & __GFP_DMA32) && (page_to_pfn(p) >= 0x00100000UL));