From mboxrd@z Thu Jan 1 00:00:00 1970 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 DC4E7C43334 for ; Tue, 7 Jun 2022 22:31:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1382323AbiFGWaD (ORCPT ); Tue, 7 Jun 2022 18:30:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54462 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1380819AbiFGVRA (ORCPT ); Tue, 7 Jun 2022 17:17:00 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CCF4014D11; Tue, 7 Jun 2022 11:57:45 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6A6156156D; Tue, 7 Jun 2022 18:57:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 74836C385A2; Tue, 7 Jun 2022 18:57:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1654628264; bh=llGja+X4n31hJKn0deRxlhzf0jQ73Msyq0QGEx0Miko=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yj7gN2GxexagHeJiuI1KL5CTz4Op8ZSJxvbkRF5zfy/ygmPE6I+C3GckdHS0D91HI DidBllu95RduezUnrCm0mkz8dcpzlW1L0olEIZHitmf/JaN1+q4PzsxHKGxotju4mW NeYcnF7le05UNGAZID2Hl/V2Sh5s23seFeLPrUlk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Chuansheng Liu , Thomas Zimmermann , Geert Uytterhoeven , Javier Martinez Canillas , Sasha Levin Subject: [PATCH 5.18 266/879] fbdev: defio: fix the pagelist corruption Date: Tue, 7 Jun 2022 18:56:24 +0200 Message-Id: <20220607165010.570589106@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220607165002.659942637@linuxfoundation.org> References: <20220607165002.659942637@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Chuansheng Liu [ Upstream commit 856082f021a28221db2c32bd0531614a8382be67 ] 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) Signed-off-by: Chuansheng Liu 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: Thomas Zimmermann Link: https://patchwork.freedesktop.org/patch/msgid/20220318005003.51810-1-chuansheng.liu@intel.com Signed-off-by: Sasha Levin --- 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 842c66b3e33d..6aaf6d0abf39 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; @@ -213,6 +212,8 @@ 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); @@ -220,6 +221,12 @@ 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); -- 2.35.1