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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 BC5C3C43331 for ; Thu, 2 Apr 2020 16:38:59 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 865132074D for ; Thu, 2 Apr 2020 16:38:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="XBnfkt6B" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 865132074D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject: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=/1F6Kv42p1FZkh//6IFhTAMh7LDadCTgQAQTkH8nnmI=; b=XBnfkt6B155fr9 Rsx8cToX2Tv+kJQXnQIHIzf8FSlbmcWyuUyO0313su2ob7YAnP5bTty2Sz0SVpafGsE0JRufAA+Pp MBNCQTYlPmAbE5h+bXH9KfE3RujL5qxRyZ5rS5b3z1aC5RiCrx724ncZFw3mQdE5cc+OwextQR99H TPinEWoGSsNFksVL9gfvuNUgaCeA96e71auWNLa6H+M6im4S/sYzGVHo6cHU9RLwPwBDOZthBVSLC UMComik2MKp3sOAdNUwpwubabl0EjCJc5mVsMPONBm12fbpdB7YNX2MOhDE0smP6bhrJqpTlyOu6z LtHOASTptUCNO/MPddtw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jK2rr-0007ba-1P; Thu, 02 Apr 2020 16:38:59 +0000 Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jK2rk-0007bD-EF; Thu, 02 Apr 2020 16:38:52 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 7F0B03056DE; Thu, 2 Apr 2020 18:38:49 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 423372B0DE293; Thu, 2 Apr 2020 18:38:49 +0200 (CEST) Date: Thu, 2 Apr 2020 18:38:49 +0200 From: Peter Zijlstra To: Zhenyu Ye Subject: Re: [RFC PATCH v5 4/8] mm: tlb: Pass struct mmu_gather to flush_pmd_tlb_range Message-ID: <20200402163849.GM20713@hirez.programming.kicks-ass.net> References: <20200331142927.1237-1-yezhenyu2@huawei.com> <20200331142927.1237-5-yezhenyu2@huawei.com> <20200331151331.GS20730@hirez.programming.kicks-ass.net> <20200401122004.GE20713@hirez.programming.kicks-ass.net> <53675fb9-21c7-5309-07b8-1bbc1e775f9b@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <53675fb9-21c7-5309-07b8-1bbc1e775f9b@huawei.com> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, catalin.marinas@arm.com, linux-mm@kvack.org, guohanjun@huawei.com, will@kernel.org, linux-arch@vger.kernel.org, yuzhao@google.com, corbet@lwn.net, maz@kernel.org, steven.price@arm.com, arm@kernel.org, Dave.Martin@arm.com, arnd@arndb.de, suzuki.poulose@arm.com, npiggin@gmail.com, zhangshaokun@hisilicon.com, broonie@kernel.org, rostedt@goodmis.org, prime.zeng@hisilicon.com, kuhn.chenqun@huawei.com, tglx@linutronix.de, linux-arm-kernel@lists.infradead.org, xiexiangyou@huawei.com, tony.luck@intel.com, vgupta@synopsys.com, linux-kernel@vger.kernel.org, aneesh.kumar@linux.ibm.com, akpm@linux-foundation.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Apr 02, 2020 at 07:24:04PM +0800, Zhenyu Ye wrote: > Thanks for your detailed explanation. I notice that you used > `tlb_end_vma` replace `flush_tlb_range`, which will call `tlb_flush`, > then finally call `flush_tlb_range` in generic code. However, some > architectures define tlb_end_vma|tlb_flush|flush_tlb_range themselves, > so this may cause problems. > > For example, in s390, it defines: > > #define tlb_end_vma(tlb, vma) do { } while (0) > > And it doesn't define it's own flush_pmd_tlb_range(). So there will be > a mistake if we changed flush_pmd_tlb_range() using tlb_end_vma(). > > Is this really a problem or something I understand wrong ? If tlb_end_vma() is a no-op, then tlb_finish_mmu() will do: tlb_flush_mmu() -> tlb_flush_mmu_tlbonly() -> tlb_flush() And s390 has tlb_flush(). If tlb_end_vma() is not a no-op and it calls tlb_flush_mmu_tlbonly(), then tlb_finish_mmu()'s invocation of tlb_flush_mmu_tlbonly() will terniate early due o no flags set. IOW, it should all just work. FYI the whole tlb_{start,end}_vma() thing is a only needed when the architecture doesn't implement tlb_flush() and instead default to using flush_tlb_range(), at which point we need to provide a 'fake' vma. At the time I audited all architectures and they only look at VM_EXEC (to do $I invalidation) and VM_HUGETLB (for pmd level invalidations), but I forgot which architectures that were. But that is all legacy code; eventually we'll get all archs a native tlb_flush() and this can go away. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel