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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CB1B1C54E5D for ; Thu, 14 Mar 2024 17:01:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:Message-ID:In-Reply-To: Subject:cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=laa5rmTR9YzA7OHEq+ktTVA/tdNddBWW9uDlH0STbsg=; b=1JFWtan0PIXCUFyWYrk0pp7e1s 9Gw6zbOzGRJbTaywzdre7X9rIC0Qq3SdugMiUYvt1T1Id2YJmLdSoqVhUeZzvc4Voeqs0wwOaB6s/ FcidlTmmKAWXU+iUpoJJtvOvkPPDysqYhXJFvoEw/vp27zKUXXTCOivfwDlxP8U2s6Tjfa9pSWszq 3xycp8ijYgFTVOQhfrETuBYuEVnBa42BIOTHfSdrf9y8bNvp9EOSw4OHTC6OrqZ70NyIgfWPXA56Q mhq0mzbF49Z9x9ILZVHEdOlsvrq0BsE2PNvqtB+hWE93l2ChX9fRkDduz6We+6zCfbp+Mrw3IZSX5 xa9c4G2w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rkoS2-0000000F4f0-2vO1; Thu, 14 Mar 2024 17:01:06 +0000 Received: from gentwo.org ([2a02:4780:10:3cd9::1]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rkoRz-0000000F4eA-10Es for linux-arm-kernel@lists.infradead.org; Thu, 14 Mar 2024 17:01:05 +0000 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240314_100103_327396_6761FF8C X-CRM114-Status: UNSURE ( 8.92 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel