From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: Re: [PATCH AUTOSEL 5.2 13/23] drm/i915/userptr: Acquire the page lock around set_page_dirty() Date: Thu, 12 Sep 2019 18:50:43 -0400 Message-ID: <20190912225043.GE1546@sasha-vm> References: <20190903162424.6877-1-sashal@kernel.org> <20190903162424.6877-13-sashal@kernel.org> <36993214-6ce7-260f-68c7-6fbb0630143f@mageia.org> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; Format="flowed" Content-Transfer-Encoding: base64 Return-path: Content-Disposition: inline In-Reply-To: <36993214-6ce7-260f-68c7-6fbb0630143f@mageia.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Thomas Backlund Cc: Jani Nikula , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org List-Id: dri-devel@lists.freedesktop.org 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vger.kernel.org via listexpand id S1727277AbfILWuv (ORCPT ); Thu, 12 Sep 2019 18:50:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:50414 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726784AbfILWuv (ORCPT ); Thu, 12 Sep 2019 18:50:51 -0400 Received: from localhost (unknown [62.28.240.114]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 99850206CD; Thu, 12 Sep 2019 22:50:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568328649; bh=owY8tPeH3sQTQ1Of9qzuZcG6Wih+amHz+jK7tLWasOk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=h8wu/A+5V8cKq3un2s3rZj0jka7IbZijhnVYw3T6vO1MqXQT/DT2joHrd/L8gGBby xojrTGXctns42qnURxBOc2fQN2i24Si8GDhDFl3MX0uBtR70O4Y42mb7TN8pDE5IGC OqW7SaJdbaekzEY8lo32m0pv3IyFhjqq8WQPNH5o= Date: Thu, 12 Sep 2019 18:50:43 -0400 From: Sasha Levin To: Thomas Backlund Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Jani Nikula , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Subject: Re: [PATCH AUTOSEL 5.2 13/23] drm/i915/userptr: Acquire the page lock around set_page_dirty() Message-ID: <20190912225043.GE1546@sasha-vm> References: <20190903162424.6877-1-sashal@kernel.org> <20190903162424.6877-13-sashal@kernel.org> <36993214-6ce7-260f-68c7-6fbb0630143f@mageia.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <36993214-6ce7-260f-68c7-6fbb0630143f@mageia.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 12, 2019 at 11:51:33PM +0300, Thomas Backlund wrote: >Den 03-09-2019 kl. 19:24, skrev Sasha Levin: >>From: Chris Wilson >> >>[ Upstream commit aa56a292ce623734ddd30f52d73f527d1f3529b5 ] >> >>set_page_dirty says: >> >> For pages with a mapping this should be done under the page lock >> for the benefit of asynchronous memory errors who prefer a >> consistent dirty state. This rule can be broken in some special >> cases, but should be better not to. >> >>Under those rules, it is only safe for us to use the plain set_page_dirty >>calls for shmemfs/anonymous memory. Userptr may be used with real >>mappings and so needs to use the locked version (set_page_dirty_lock). >> >>Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203317 >>Fixes: 5cc9ed4b9a7a ("drm/i915: Introduce mapping of user pages into video memory (userptr) ioctl") >>References: 6dcc693bc57f ("ext4: warn when page is dirtied without buffers") >>Signed-off-by: Chris Wilson >>Cc: Tvrtko Ursulin >>Cc: stable@vger.kernel.org >>Reviewed-by: Tvrtko Ursulin >>Link: https://patchwork.freedesktop.org/patch/msgid/20190708140327.26825-1-chris@chris-wilson.co.uk >>(cherry picked from commit cb6d7c7dc7ff8cace666ddec66334117a6068ce2) >>Signed-off-by: Jani Nikula >>Signed-off-by: Sasha Levin >>--- >> drivers/gpu/drm/i915/i915_gem_userptr.c | 10 +++++++++- >> 1 file changed, 9 insertions(+), 1 deletion(-) >> >>diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c >>index 8079ea3af1039..b1fc15c7f5997 100644 >>--- a/drivers/gpu/drm/i915/i915_gem_userptr.c >>+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c >>@@ -678,7 +678,15 @@ i915_gem_userptr_put_pages(struct drm_i915_gem_object *obj, >> for_each_sgt_page(page, sgt_iter, pages) { >> if (obj->mm.dirty) >>- set_page_dirty(page); >>+ /* >>+ * As this may not be anonymous memory (e.g. shmem) >>+ * but exist on a real mapping, we have to lock >>+ * the page in order to dirty it -- holding >>+ * the page reference is not sufficient to >>+ * prevent the inode from being truncated. >>+ * Play safe and take the lock. >>+ */ >>+ set_page_dirty_lock(page); >> mark_page_accessed(page); >> put_page(page); >> > > >Please drop this one from all 5.2 and 4.19 stable queues > >It has now been reverted in Linus tree: >https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=505a8ec7e11ae5236c4a154a1e24ef49a8349600 Now dropped, thank you. -- Thanks, Sasha