From patchwork Thu Mar 17 05:46:02 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuansheng Liu X-Patchwork-Id: 12783538 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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 18FD2C433F5 for ; Thu, 17 Mar 2022 06:02:26 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 26A1210E0FD; Thu, 17 Mar 2022 06:02:25 +0000 (UTC) Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by gabe.freedesktop.org (Postfix) with ESMTPS id C922B10EB6A for ; Thu, 17 Mar 2022 06:02:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1647496943; x=1679032943; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=yfF1kJ6Hk/ECy7Ze3UDspa6TFID/BLpEc4PFebiIheY=; b=IBQHQvziN+Yz5BYTlYa8yG8tiiN+Are/TOP1PnstB1fxq0i6xDMoYR8p jMvxQRmUuUqJIACoo2jG8fyc0fx8r8yBM8paKCE4ALL36hiE6JlV/ZcEy LDiCLbap/cb7Iu/ALoHHJ+88polg4n07JEIJj0HDH9Twm06WBt1NklDEM MMbfJwKKVDSeMc/IxIMF196WKgpxxYthDBDGsKEvriG/NTw9blZ5zgJhl zxLjuSxTsJC+PRKrvXp1BMGB3P1v9P5wABIwVdY1m4QZpf/TNgICaXLTd 8T+YaYksmizaRFzOq8mBNNOZjjzqHxaGF5h/2P7kufIKxvS068Brv9XLC A==; X-IronPort-AV: E=McAfee;i="6200,9189,10288"; a="244243735" X-IronPort-AV: E=Sophos;i="5.90,188,1643702400"; d="scan'208";a="244243735" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Mar 2022 23:02:20 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.90,188,1643702400"; d="scan'208";a="557791023" Received: from cliu38-mobl3.sh.intel.com ([10.239.147.106]) by orsmga008.jf.intel.com with ESMTP; 16 Mar 2022 23:02:18 -0700 From: Chuansheng Liu To: jayalk@intworks.biz, daniel@ffwll.ch, deller@gmx.de Subject: [PATCH] fbdev: defio: fix the pagelist corruption Date: Thu, 17 Mar 2022 13:46:02 +0800 Message-Id: <20220317054602.28846-1-chuansheng.liu@intel.com> X-Mailer: git-send-email 2.25.0.rc2 MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-fbdev@vger.kernel.org, chuansheng.liu@intel.com, tzimmermann@suse.de, dri-devel@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Easily hit the below list corruption: == list_add corruption. prev->next should be next (ffffffffc0ceb090), but was ffffec604507edc8. (prev=ffffec604507edc8). WARNING: CPU: 65 PID: 3959 at lib/list_debug.c:26 __list_add_valid+0x53/0x80 CPU: 65 PID: 3959 Comm: fbdev Tainted: G U RIP: 0010:__list_add_valid+0x53/0x80 Call Trace: fb_deferred_io_mkwrite+0xea/0x150 do_page_mkwrite+0x57/0xc0 do_wp_page+0x278/0x2f0 __handle_mm_fault+0xdc2/0x1590 handle_mm_fault+0xdd/0x2c0 do_user_addr_fault+0x1d3/0x650 exc_page_fault+0x77/0x180 ? asm_exc_page_fault+0x8/0x30 asm_exc_page_fault+0x1e/0x30 RIP: 0033:0x7fd98fc8fad1 == Figure out the race happens when one process is adding &page->lru into the pagelist tail in fb_deferred_io_mkwrite(), another process is re-initializing the same &page->lru in fb_deferred_io_fault(), which is not protected by the lock. This fix is to init all the page lists one time during initialization, it not only fixes the list corruption, but also avoids INIT_LIST_HEAD() redundantly. Fixes: 105a940416fc ("fbdev/defio: Early-out if page is already enlisted") Cc: Thomas Zimmermann Signed-off-by: Chuansheng Liu Reviewed-by: Javier Martinez Canillas Reviewed-by: Thomas Zimmermann --- drivers/video/fbdev/core/fb_defio.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c index 98b0f23bf5e2..eafb66ca4f28 100644 --- a/drivers/video/fbdev/core/fb_defio.c +++ b/drivers/video/fbdev/core/fb_defio.c @@ -59,7 +59,6 @@ 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; @@ -220,6 +219,8 @@ static void fb_deferred_io_work(struct work_struct *work) void fb_deferred_io_init(struct fb_info *info) { struct fb_deferred_io *fbdefio = info->fbdefio; + struct page *page; + int i; BUG_ON(!fbdefio); mutex_init(&fbdefio->lock); @@ -227,6 +228,12 @@ void fb_deferred_io_init(struct fb_info *info) INIT_LIST_HEAD(&fbdefio->pagelist); if (fbdefio->delay == 0) /* set a default of 1 s */ fbdefio->delay = HZ; + + /* initialize all the page lists one time */ + for (i = 0; i < info->fix.smem_len; i += PAGE_SIZE) { + page = fb_deferred_io_page(info, i); + INIT_LIST_HEAD(&page->lru); + } } EXPORT_SYMBOL_GPL(fb_deferred_io_init);