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=-3.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS autolearn=no 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 54725C388F7 for ; Sun, 8 Nov 2020 00:56:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0ABD0208FE for ; Sun, 8 Nov 2020 00:56:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604797008; bh=/261giqM3SGf4BphJk8rBUodxqpoAGphORKU+/3G2W0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=fb2uHxcE1HHLpRAc6LKph44LyUAA3k4ZVsSQD4yg4d1uq6xLSymd/hwYGkPWkQxI5 4PPi3XGXTt+lCkahvbM36q3PAJaC4/f8BrcWG0yw9KgpNaJ3C6wDUfA2tDMyiTR3Cb XAhGyobMT8zuksI35iUsfNVdLmUbrk9GuW3I/5/w= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726470AbgKHA4r (ORCPT ); Sat, 7 Nov 2020 19:56:47 -0500 Received: from mail.kernel.org ([198.145.29.99]:46080 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725838AbgKHA4q (ORCPT ); Sat, 7 Nov 2020 19:56:46 -0500 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2727520885; Sun, 8 Nov 2020 00:56:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604797006; bh=/261giqM3SGf4BphJk8rBUodxqpoAGphORKU+/3G2W0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=xwxjPDl+XMKb88dppa9KT+Klv8aXbRwQ9UGlyqntIQflE109bvZuC45A7d+VPQSkP HlaRq/4a0y7UT/eq66pLNjY31kTs3c/Oe55Q7eIP0wyTXMGzGwyVV++cJEmvTutyvv hDDjFCRLopKIALYmz5iaDG/uEfbBN4f5SlzK+O/U= Date: Sat, 7 Nov 2020 16:56:45 -0800 From: Andrew Morton To: Stefan Agner Cc: minchan@kernel.org, ngupta@vflare.org, sergey.senozhatsky.work@gmail.com, sjenning@linux.vnet.ibm.com, gregkh@linuxfoundation.org, arnd@arndb.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/zsmalloc: include sparsemem.h for MAX_PHYSMEM_BITS Message-Id: <20201107165645.1b139b595b6b64feaca61bcb@linux-foundation.org> In-Reply-To: References: X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 7 Nov 2020 16:22:06 +0100 Stefan Agner wrote: > Most architectures define MAX_PHYSMEM_BITS in asm/sparsemem.h and don't > include it in asm/pgtable.h. Include asm/sparsemem.h directly to get > the MAX_PHYSMEM_BITS define on all architectures. > > This fixes a crash when accessing zram on 32-bit ARM platform with LPAE and > more than 4GB of memory: > Unable to handle kernel NULL pointer dereference at virtual address 00000000 Mysterious. Presumably without this include, some compilation unit is picking up the wrong value of MAX_PHYSMEM_BITS? But I couldn't actually see where/how this occurs. Can you please explain further?