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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 37689C4321E for ; Fri, 7 Sep 2018 21:43:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EB2EC20844 for ; Fri, 7 Sep 2018 21:43:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EB2EC20844 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org 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 S1730880AbeIHC0W (ORCPT ); Fri, 7 Sep 2018 22:26:22 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:56894 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729993AbeIHC0W (ORCPT ); Fri, 7 Sep 2018 22:26:22 -0400 Received: from localhost (ip-213-127-74-90.ip.prioritytelecom.net [213.127.74.90]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id E0C26BBF; Fri, 7 Sep 2018 21:43:25 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Will Deacon , "Peter Zijlstra (Intel)" , Rik van Riel , Nicholas Piggin , David Miller , Martin Schwidefsky , Michael Ellerman , stable@kernel.org, Linus Torvalds Subject: [PATCH 3.18 17/29] mm/tlb: Remove tlb_remove_table() non-concurrent condition Date: Fri, 7 Sep 2018 23:10:38 +0200 Message-Id: <20180907210910.759447458@linuxfoundation.org> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180907210909.523240901@linuxfoundation.org> References: <20180907210909.523240901@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Peter Zijlstra commit a6f572084fbee8b30f91465f4a085d7a90901c57 upstream. 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(). Fixes: 267239116987 ("mm, powerpc: move the RCU page-table freeing into generic code") Reported-by: Will Deacon Signed-off-by: Peter Zijlstra (Intel) Acked-by: Rik van Riel Acked-by: Will Deacon Cc: Nicholas Piggin Cc: David Miller Cc: Martin Schwidefsky Cc: Michael Ellerman Cc: stable@kernel.org Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/memory.c | 9 --------- 1 file changed, 9 deletions(-) --- a/mm/memory.c +++ b/mm/memory.c @@ -359,15 +359,6 @@ void tlb_remove_table(struct mmu_gather { struct mmu_table_batch **batch = &tlb->batch; - /* - * When there's less then two users of this mm there cannot be a - * concurrent page-table walk. - */ - if (atomic_read(&tlb->mm->mm_users) < 2) { - __tlb_remove_table(table); - return; - } - if (*batch == NULL) { *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN); if (*batch == NULL) {