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 36E27C54E60 for ; Thu, 14 Mar 2024 17:01:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 91093800CA; Thu, 14 Mar 2024 13:01:05 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8C0B2800B4; Thu, 14 Mar 2024 13:01:05 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7AFD0800CA; Thu, 14 Mar 2024 13:01:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 6D1F7800B4 for ; Thu, 14 Mar 2024 13:01:05 -0400 (EDT) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id D04501216DA for ; Thu, 14 Mar 2024 17:01:04 +0000 (UTC) X-FDA: 81896259648.07.4CA7BC5 Received: from gentwo.org (gentwo.org [62.72.0.81]) by imf22.hostedemail.com (Postfix) with ESMTP id C6AFEC002F for ; Thu, 14 Mar 2024 17:01:02 +0000 (UTC) Authentication-Results: imf22.hostedemail.com; dkim=none; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=linux.com (policy=none); spf=softfail (imf22.hostedemail.com: 62.72.0.81 is neither permitted nor denied by domain of cl@linux.com) smtp.mailfrom=cl@linux.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1710435663; 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; bh=jvtJ7LF8w/3Xbr15t+lzrOxGf5qDBW+D14Iqi8xCy1c=; b=acxgvRhY8z59PBKtPHe/POhV58wo3SqXsny92r8nX3cRzsIoNhA//36LZ/SiXhNkFeHk1Y 5VH+p+ohiITlAOkDtddRAJQ/NwSlUEz91cPflJojGIc1nKSWFabSgmGoHibcnecdy17ZrJ L1wsjWlHDv7vpsLaDXPmPrZ61UhRSmk= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=none; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=linux.com (policy=none); spf=softfail (imf22.hostedemail.com: 62.72.0.81 is neither permitted nor denied by domain of cl@linux.com) smtp.mailfrom=cl@linux.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1710435663; a=rsa-sha256; cv=none; b=lhEuBqVCf+v2TcXoyEJbLjO4/ZtmyTeySVitkQa6eQXv34NgceYhhDo83EJjsdjkhq6Rwa HLPLVvm3kB+4q4Jpo7l4JBGGHwcEjDtCuNBGsO7f9ZYSBUNPOTeftcnTwawF2/xU8jXPnx Z2zZVPujY+MjrsYZWzuMmvJVWWYepsk= Received: by gentwo.org (Postfix, from userid 1003) id 08A9040AB2; Thu, 14 Mar 2024 10:01:01 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by gentwo.org (Postfix) with ESMTP id 0604D40AAD; Thu, 14 Mar 2024 10:01:01 -0700 (PDT) Date: Thu, 14 Mar 2024 10:01:01 -0700 (PDT) From: "Christoph Lameter (Ampere)" To: "Russell King (Oracle)" cc: Marek Szyprowski , Catalin Marinas , Sudeep Holla , Mark Rutland , "linux-pm@vger.kernel.org" , "Rafael J. Wysocki" , Viresh Kumar , Will Deacon , Jonathan.Cameron@huawei.com, Matteo.Carlini@arm.com, Valentin.Schneider@arm.com, akpm@linux-foundation.org, anshuman.khandual@arm.com, Eric Mackay , dave.kleikamp@oracle.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, robin.murphy@arm.com, vanshikonda@os.amperecomputing.com, yang@os.amperecomputing.com, Nishanth Menon , Stephen Boyd Subject: Re: [PATCH v3] ARM64: Dynamically allocate cpumasks and increase supported CPUs to 512 In-Reply-To: Message-ID: References: <9352f410-9dad-ac89-181a-b3cfc86176b8@linux.com> <432c1980-b00f-4b07-9e24-0bec52ccb5d6@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset=US-ASCII X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: C6AFEC002F X-Stat-Signature: c3ab1sbbg88zme44mz4y45ocsgexyimo X-HE-Tag: 1710435662-894750 X-HE-Meta: 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 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: List-Subscribe: List-Unsubscribe: On Thu, 14 Mar 2024, Russell King (Oracle) wrote: >> It is really surprising that this didn't blow up for anyone else so >> far... This means that the $subject patch is fine. > > Wow. I guess we've been lucky with that allocation hitting memory > containing zeros. Well done at tracking it down! It would have blown up with slub_debug because that includes poisoning the contents of all allocations via the slab allocator. Why did that not occur? We should have seen a backtrace with data in registers etc showing poisoning values for an unitialized object. Note that this was indeed triggered by OFFSTACK because (z)alloc_cpumask_var() only generates a kmalloc allocation if that option is set. The config option was never set before my patch was applied on ARM64.