From patchwork Fri Mar 18 00:50:03 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuansheng Liu X-Patchwork-Id: 12784740 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 00765C433EF for ; Fri, 18 Mar 2022 01:06:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231351AbiCRBHi (ORCPT ); Thu, 17 Mar 2022 21:07:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50958 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231346AbiCRBHh (ORCPT ); Thu, 17 Mar 2022 21:07:37 -0400 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B501F1AFE86 for ; Thu, 17 Mar 2022 18:06:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1647565579; x=1679101579; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=VWC6HUH11zHEaXwf+ALnIMxVDNWIX7ILw0OIDe/QfRw=; b=CY76ZgazjiIpS+QD8Iu2pA2ufAdBC3vmwgVAqp5EeUnf/5djiWV3H3YO mGeAwm93MYMjPirJKLqkg/AyGLt/YEirD2zYweDbrfx6grOZrxRJcsH4L uJgTkrs4PnEDUj8pLyLG76JhxW1IJDQgyyCzHlL1rj2I9EKc4wiWBKfsX L7QrlSA2LWyWeGtq4RTBrtMwLkL+zQIjWs/wKGKsX+hfyT6jZRmWDe1yu hGXvXecocfw37RHG5OKauadKb863KFhHWtfMwvTXXZkqbvFCwSmaRhY5I ltvMMZLdKKcUyIClO1vbpo5Q9bMqR9/h/AIJ3wAUHDvZYmLuSPAyiVOiJ Q==; X-IronPort-AV: E=McAfee;i="6200,9189,10289"; a="254575410" X-IronPort-AV: E=Sophos;i="5.90,190,1643702400"; d="scan'208";a="254575410" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2022 18:06:19 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.90,190,1643702400"; d="scan'208";a="647259586" Received: from cliu38-mobl3.sh.intel.com ([10.239.147.106]) by orsmga004.jf.intel.com with ESMTP; 17 Mar 2022 18:06:16 -0700 From: Chuansheng Liu To: jayalk@intworks.biz, daniel@ffwll.ch, deller@gmx.de Cc: linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, chuansheng.liu@intel.com, Thomas Zimmermann , Geert Uytterhoeven , Javier Martinez Canillas Subject: [PATCH v2] fbdev: defio: fix the pagelist corruption Date: Fri, 18 Mar 2022 08:50:03 +0800 Message-Id: <20220318005003.51810-1-chuansheng.liu@intel.com> X-Mailer: git-send-email 2.25.0.rc2 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org 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. V2: change "int i" to "unsigned int i" (Geert Uytterhoeven) Fixes: 105a940416fc ("fbdev/defio: Early-out if page is already enlisted") Cc: Thomas Zimmermann Cc: Geert Uytterhoeven Reviewed-by: Javier Martinez Canillas Reviewed-by: Thomas Zimmermann Signed-off-by: Chuansheng Liu --- 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..a1da54016c88 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; + unsigned 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);