From patchwork Thu Feb 10 14:11:11 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Zimmermann X-Patchwork-Id: 541577 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 085CEC433EF for ; Thu, 10 Feb 2022 14:11:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239028AbiBJOLZ (ORCPT ); Thu, 10 Feb 2022 09:11:25 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:32966 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235081AbiBJOLY (ORCPT ); Thu, 10 Feb 2022 09:11:24 -0500 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4D135C1 for ; Thu, 10 Feb 2022 06:11:26 -0800 (PST) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 05C2921114; Thu, 10 Feb 2022 14:11:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1644502285; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=2m0LxcQyStkLKfwrGKW8CTnydl47YLuxekTjHFPor3k=; b=p3eeCS/JtdPquyZV0tmRg/kuPMQ3S/X0zZMON8eA2agA7jU4PBpgyd+Jya0v2EhYUXZSsC IZ+/zwAAu9OC283sGY4qzdtynFR+Yota83D29n4GnOLHcHL2poKR1SqVQ8xGBPNDxv4/mE NKPqKFWXRLJoJelWRsP6ZcNSs7aaOKg= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1644502285; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=2m0LxcQyStkLKfwrGKW8CTnydl47YLuxekTjHFPor3k=; b=wZ0jBTAVWnHk37m+aYTSRrx/sJMEchtxBXEeMhAt4v2O1eBNqJfP4wp+GGKmy/JAISQfTP aBZYLG60w5pIUdCQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id C05C913B9E; Thu, 10 Feb 2022 14:11:24 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id IP8HLgwdBWIPaQAAMHmgww (envelope-from ); Thu, 10 Feb 2022 14:11:24 +0000 From: Thomas Zimmermann To: daniel@ffwll.ch, javierm@redhat.com, noralf@tronnes.org, andriy.shevchenko@linux.intel.com, deller@gmx.de, bernie@plugable.com, jayalk@intworks.biz Cc: dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-staging@lists.linux.dev, Thomas Zimmermann Subject: [PATCH 1/2] fbdev/defio: Early-out if page is already enlisted Date: Thu, 10 Feb 2022 15:11:11 +0100 Message-Id: <20220210141111.5231-2-tzimmermann@suse.de> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220210141111.5231-1-tzimmermann@suse.de> References: <20220210141111.5231-1-tzimmermann@suse.de> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org Return early if a page is already in the list of dirty pages for deferred I/O. This can be detected if the page's list head is not empty. Keep the list head initialized while the page is not enlisted to make this work reliably. Signed-off-by: Thomas Zimmermann Acked-by: Sam Ravnborg --- drivers/video/fbdev/core/fb_defio.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c index a591d291b231..3727b1ca87b1 100644 --- a/drivers/video/fbdev/core/fb_defio.c +++ b/drivers/video/fbdev/core/fb_defio.c @@ -59,6 +59,7 @@ static vm_fault_t fb_deferred_io_fault(struct vm_fault *vmf) printk(KERN_ERR "no mapping available\n"); BUG_ON(!page->mapping); + INIT_LIST_HEAD(&page->lru); page->index = vmf->pgoff; vmf->page = page; @@ -122,17 +123,19 @@ static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) */ lock_page(page); + /* + * This check is to catch the case where a new process could start + * writing to the same page through a new pte. this new access + * can cause the mkwrite even when the original ps's pte is marked + * writable. + */ + if (!list_empty(&page->lru)) + goto page_already_added; + /* we loop through the pagelist before adding in order to keep the pagelist sorted */ list_for_each_entry(cur, &fbdefio->pagelist, lru) { - /* this check is to catch the case where a new - process could start writing to the same page - through a new pte. this new access can cause the - mkwrite even when the original ps's pte is marked - writable */ - if (unlikely(cur == page)) - goto page_already_added; - else if (cur->index > page->index) + if (cur->index > page->index) break; } @@ -194,7 +197,7 @@ static void fb_deferred_io_work(struct work_struct *work) /* clear the list */ list_for_each_safe(node, next, &fbdefio->pagelist) { - list_del(node); + list_del_init(node); } mutex_unlock(&fbdefio->lock); }