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 X-Spam-Level: X-Spam-Status: No, score=-9.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0DF17C38A2B for ; Thu, 16 Apr 2020 15:46:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D322422244 for ; Thu, 16 Apr 2020 15:46:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Sc6BiJMI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2896197AbgDPPqQ (ORCPT ); Thu, 16 Apr 2020 11:46:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49070 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S2442555AbgDPPqN (ORCPT ); Thu, 16 Apr 2020 11:46:13 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9613CC061A0C for ; Thu, 16 Apr 2020 08:46:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description; bh=kMLTih8CX/GbD68c1YCwFJOmEFKi+9QpHvxsolCFJz4=; b=Sc6BiJMIFfeDtTxK3dZEyjKYGF 21+2xVXAwK0Hl6SI+MezZyD1Je9z5982qOQBkRo1ip6Cv3ygeeNpdH18EG/WbsJHUgeVvkgooZSUM J2lrSueDn4CjTNT4mm9Q77ixHQa5L0LhC8ZHsKPTXS9SDbKrynU820RlJigqZQ3P+tos9Vv8CnGN7 LUtFeN+KLIe3sNVZnrPIinCYpGCi9DzZGZb1dVqtwCRL+iFkv630+s50BGLOG+64eTBtLVQJ71JpV uH4IVBydJBRsPI1GUBl1/up5EkFQicGIDxWI9/AdX1lAS9NamrbMJY726ERwElcQtexNmy42tFktN M9pN7P+Q==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jP6iN-00006X-Fp; Thu, 16 Apr 2020 15:46:07 +0000 From: Matthew Wilcox To: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Cc: "Matthew Wilcox (Oracle)" Subject: [PATCH v2 3/5] mm: Convert writeback BUG to WARN_ON Date: Thu, 16 Apr 2020 08:46:04 -0700 Message-Id: <20200416154606.306-4-willy@infradead.org> X-Mailer: git-send-email 2.21.1 In-Reply-To: <20200416154606.306-1-willy@infradead.org> References: <20200416154606.306-1-willy@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: "Matthew Wilcox (Oracle)" If this BUG() ever triggers, we'll have a dead system with no particular information. Dumping the page will give us a fighting chance of debugging the problem, and I think it's safe for us to just continue if we try to clear the writeback bit on a page which already has the writeback bit clear. Signed-off-by: Matthew Wilcox (Oracle) --- mm/filemap.c | 4 +--- mm/page-writeback.c | 5 +++++ 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index b7c5d2402370..401b24d980ba 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1293,9 +1293,7 @@ void end_page_writeback(struct page *page) rotate_reclaimable_page(page); } - if (!test_clear_page_writeback(page)) - BUG(); - + test_clear_page_writeback(page); smp_mb__after_atomic(); wake_up_page(page, PG_writeback); } diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 7326b54ab728..ebaf0d8263a6 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -2718,6 +2718,11 @@ int test_clear_page_writeback(struct page *page) struct lruvec *lruvec; int ret; + if (WARN_ON(!PageWriteback(page))) { + dump_page(page, "!writeback"); + return false; + } + memcg = lock_page_memcg(page); lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page)); if (mapping && mapping_use_writeback_tags(mapping)) { -- 2.25.1