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 90057C4345F for ; Wed, 1 May 2024 10:05:08 +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-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID: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=GU/SKRvbeonTJMUTjwF7K5qUGmjOARC/5kkzVGPGHjw=; b=Uq3g1SYrCls6Yt OXY+FaVoa1Mq2hoM1dGaE/z7ATZ9ZE3VImCjqcazkIgfEoO5tosOtHcvp5e3rAuHoGDwJ8RWMPZde FFNTjptUeinauenrmLlNgJTSRVwfg2BRmWq0H5Tm3qny+Io3Qt9Zox0rywsw5tSEaoFqR6UU6MxOH SnYrjatBxFL/APDIRtselz7OwxlK4+3B13VhsvFdW8xCGNK6SCfs+kCuPEGzwXAyIB19hNr7JyZoq u+9uWgXRv27BxKp1nG+9yOL7uG8ZQ6mraRoA3Rc7TEjv6p/5OCoJQPENs58RhmHWN2GaYAvWfvzeK 1ZJVolceFDL2oxuRXKyQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1s26pd-000000092zu-0TJq; Wed, 01 May 2024 10:04:57 +0000 Received: from sin.source.kernel.org ([2604:1380:40e1:4800::1]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1s26pZ-000000092zF-3cGe for linux-arm-kernel@lists.infradead.org; Wed, 01 May 2024 10:04:55 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id 2486ECE12A4; Wed, 1 May 2024 10:04:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3DA12C113CC; Wed, 1 May 2024 10:04:47 +0000 (UTC) Date: Wed, 1 May 2024 11:04:44 +0100 From: Catalin Marinas To: Ryan Roberts Cc: Will Deacon , Mark Rutland , Anshuman Khandual , Andrew Morton , Zi Yan , "Aneesh Kumar K.V" , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2] arm64/mm: pmd_mkinvalid() must handle swap pmds Message-ID: References: <20240430133138.732088-1-ryan.roberts@arm.com> <171449974870.639201.3165060270571039049.b4-ty@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240501_030454_105978_D1B84798 X-CRM114-Status: GOOD ( 20.85 ) 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-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, May 01, 2024 at 09:05:17AM +0100, Ryan Roberts wrote: > On 30/04/2024 18:57, Catalin Marinas wrote: > > On Tue, 30 Apr 2024 14:31:38 +0100, Ryan Roberts wrote: > >> __split_huge_pmd_locked() can be called for a present THP, devmap or > >> (non-present) migration entry. It calls pmdp_invalidate() > >> unconditionally on the pmdp and only determines if it is present or not > >> based on the returned old pmd. > >> > >> But arm64's pmd_mkinvalid(), called by pmdp_invalidate(), > >> unconditionally sets the PMD_PRESENT_INVALID flag, which causes future > >> pmd_present() calls to return true - even for a swap pmd. Therefore any > >> lockless pgtable walker could see the migration entry pmd in this state > >> and start interpretting the fields (e.g. pmd_pfn()) as if it were > >> present, leading to BadThings (TM). GUP-fast appears to be one such > >> lockless pgtable walker. > >> > >> [...] > > > > Applied to arm64 (for-next/fixes), thanks! It should land in 6.9-rc7. I > > removed the debug/test code, please send it as a separate patch for > > 6.10. > > Thanks Catalin! I'm guessing this will turn up in today's linux-next, so if I > send the tests today and Andrew puts them straight in mm-unstable (which will > goto linux-next) there is no risk that the tests are there without the fix? Or > do I need to hold off until the fix is in v6.9-rc7? It looks like we don't push for-next/fixes to linux-next, it's short-lived usually, it ends up upstream quickly. I can send the pull request later today, should turn up in mainline by tomorrow. You can add a note to your patch for Andrew that it will fail on arm64 until the fix ends up upstream. It's a matter of a couple of days anyway. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel