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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C521EC0015E for ; Sun, 23 Jul 2023 01:57:00 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 35F866B0072; Sat, 22 Jul 2023 21:57:00 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 30F956B0074; Sat, 22 Jul 2023 21:57:00 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1FD826B0075; Sat, 22 Jul 2023 21:57:00 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 0AEF26B0072 for ; Sat, 22 Jul 2023 21:57:00 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id CBE22B1BE9 for ; Sun, 23 Jul 2023 01:56:59 +0000 (UTC) X-FDA: 81041213358.14.1672E5C Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf23.hostedemail.com (Postfix) with ESMTP id 8736314000B for ; Sun, 23 Jul 2023 01:56:57 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=fd471AmZ; dmarc=none; spf=none (imf23.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1690077418; a=rsa-sha256; cv=none; b=P5YjfKWGi6yCARyCa/FVCkxvET2MmP4uAJQhjU7axgsLryo/a+S+wBtbJC5EELBRRav8UM bWdpeD3x79orEolFzCkJeDroZTTFYhJ+sJBzYkkrmJDyeuS8FHOzFMlxXs4Kx1mblIge2c 5nTXflV344UFnshgClBdQRwIKIDzVi8= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=fd471AmZ; dmarc=none; spf=none (imf23.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1690077418; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=44TAO7fZz6hxR8n6K1VxaF5RLJ5K1lVta2e75naOYuI=; b=DqzUzExtPbAXjBGRKqzb1lpIi5KsJwIqFD2LTaGThcP75/a3HpiF2XNbc32v0LaguKCGqE EZK3iHUIwA+g0ZHr+ajDqUljUAOOrrNqgRZSHxxz5SLsR3SdK1fvI3j/MZ0HSLWaEAKFZl 2b/UrSJutGZNXSk8hs5DcBBjk2SSLKI= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=44TAO7fZz6hxR8n6K1VxaF5RLJ5K1lVta2e75naOYuI=; b=fd471AmZbL4iL4EAIRqJ6GRP4x 1DRBJMV05Hv8AtPWVzmT5MKc2o9+fg/k5Tzv82JBd/Y4PwAOIreWpiNU03lRIyz+2opZg3LQ6mRW0 AbfzfVl9af5hZ5ig33UqNxgBP0g6dVgv8QYoqMzcScH2CRzSHEU/qraRu4zwaoHUdWvhh3XPhsZ01 Yd/8N0SkiwOOGKfBRGuMAOZluMw52E4zd3lRM/TVhuKIgdTiX9k6AWqOZRZWsnO6GIbFfEz/Zk1U4 vHUH0/OHR6Q4StDW01CP6YIsl6DD0JU70A5nZG+/oAUnQYzix4NizMqw3+z7NDsx90DuW49x5222B TpnUF3+A==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qNOL5-002bdT-7n; Sun, 23 Jul 2023 01:56:51 +0000 Date: Sun, 23 Jul 2023 02:56:51 +0100 From: Matthew Wilcox To: Pasha Tatashin Cc: akpm@linux-foundation.org, corbet@lwn.net, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, rick.p.edgecombe@intel.com Subject: Re: [PATCH v2 1/3] mm/page_table_check: Do WARN_ON instead of BUG_ON Message-ID: References: <20230722231508.1030269-1-pasha.tatashin@soleen.com> <20230722231508.1030269-2-pasha.tatashin@soleen.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230722231508.1030269-2-pasha.tatashin@soleen.com> X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 8736314000B X-Stat-Signature: iku1qc57qm13sfk1gsmurft6i4c5waug X-HE-Tag: 1690077417-164212 X-HE-Meta: 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 QPRE+QQa J8UvOw0Z6HOS7kqsoE6c+m2w4jgjBDhTH8hUzDRVocZYBmZI35kd0Njv2/fQpxXkqP25ITJhqVkwMRp9THq1GljK9vr0iSJ+UhMogAbkKIc49QA7sN9J6apyF/JuOC0a6XI8UiPDG7vF/7Ig2kiAGtYAnQ8ncNukDAzqVMv/5gVFCJDI/hRAUH3KirQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, Jul 22, 2023 at 11:15:06PM +0000, Pasha Tatashin wrote: > static struct page_table_check *get_page_table_check(struct page_ext *page_ext) > { > - BUG_ON(!page_ext); > + PAGE_TABLE_CHECK_WARN(!page_ext); > + > return (void *)(page_ext) + page_table_check_ops.offset; > } [...] > @@ -137,15 +144,15 @@ void __page_table_check_zero(struct page *page, unsigned int order) > struct page_ext *page_ext; > unsigned long i; > > - BUG_ON(PageSlab(page)); > + PAGE_TABLE_CHECK_WARN(PageSlab(page)); > > page_ext = page_ext_get(page); > - BUG_ON(!page_ext); > + PAGE_TABLE_CHECK_WARN(!page_ext); > for (i = 0; i < (1ul << order); i++) { > struct page_table_check *ptc = get_page_table_check(page_ext); Seems like we're going to warn about !page_ext twice? Or more than twice -- once per tail page? But then we'll crash because page_ext was NULL and offset was small?