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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 3BCB9C4321D for ; Thu, 23 Aug 2018 13:40:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EC63E208FA for ; Thu, 23 Aug 2018 13:40:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EC63E208FA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731351AbeHWRKb (ORCPT ); Thu, 23 Aug 2018 13:10:31 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:46588 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730895AbeHWRKa (ORCPT ); Thu, 23 Aug 2018 13:10:30 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 5ABA1ED1; Thu, 23 Aug 2018 06:40:45 -0700 (PDT) Received: from brain-police (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id F340A3F675; Thu, 23 Aug 2018 06:40:43 -0700 (PDT) Date: Thu, 23 Aug 2018 14:40:41 +0100 From: Will Deacon To: Peter Zijlstra Cc: torvalds@linux-foundation.org, luto@kernel.org, x86@kernel.org, bp@alien8.de, riel@surriel.com, jannh@google.com, ascannell@google.com, dave.hansen@intel.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Nicholas Piggin , David Miller , Martin Schwidefsky , Michael Ellerman Subject: Re: [PATCH 2/4] mm/tlb: Remove tlb_remove_table() non-concurrent condition Message-ID: <20180823134041.GB1496@brain-police> References: <20180822153012.173508681@infradead.org> <20180822154046.772017055@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180822154046.772017055@infradead.org> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 22, 2018 at 05:30:14PM +0200, Peter Zijlstra wrote: > Will noted that only checking mm_users is incorrect; we should also > check mm_count in order to cover CPUs that have a lazy reference to > this mm (and could do speculative TLB operations). > > If removing this turns out to be a performance issue, we can > re-instate a more complete check, but in tlb_table_flush() eliding the > call_rcu_sched(). > > Cc: stable@kernel.org > Cc: Nicholas Piggin > Cc: David Miller > Cc: Will Deacon > Cc: Martin Schwidefsky > Cc: Michael Ellerman > Fixes: 267239116987 ("mm, powerpc: move the RCU page-table freeing into generic code") > Reported-by: Will Deacon > Signed-off-by: Peter Zijlstra (Intel) > --- > mm/memory.c | 9 --------- > 1 file changed, 9 deletions(-) Acked-by: Will Deacon Cheers, Will