From patchwork Wed Aug 22 15:30:14 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Zijlstra X-Patchwork-Id: 10573025 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 736B617E0 for ; Wed, 22 Aug 2018 15:47:00 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 63F2E2B791 for ; Wed, 22 Aug 2018 15:47:00 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 57BAE2B7AA; Wed, 22 Aug 2018 15:47:00 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D98DD2B791 for ; Wed, 22 Aug 2018 15:46:59 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 004396B2521; Wed, 22 Aug 2018 11:46:59 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id ECF5D6B2522; Wed, 22 Aug 2018 11:46:58 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D70AB6B2523; Wed, 22 Aug 2018 11:46:58 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from mail-wm0-f71.google.com (mail-wm0-f71.google.com [74.125.82.71]) by kanga.kvack.org (Postfix) with ESMTP id 7ACA46B2521 for ; Wed, 22 Aug 2018 11:46:58 -0400 (EDT) Received: by mail-wm0-f71.google.com with SMTP id m129-v6so2086860wma.8 for ; Wed, 22 Aug 2018 08:46:58 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:message-id:user-agent:date:from :to:cc:subject:references:mime-version; bh=DtDo4cQQlYpJctQYVAg287e1LDGKHg+PXr5W1nBz53Q=; b=o2jm7dgGNjlprlmklYPK0kCblDyzNnKjXXbl8Iuofy3wGsdnKEtjuyMzOYuEzkjEqc /9uLO0TLphy6Cy0XPsyBCCccd3Y/8Wfk8tWlFVmL6idU81OXN4lPCGraeww+492vVoJH QfNZm26IBADGA6rhmmoOwwfnRK7wynD0m79ucIJj+RSGcAOUSFTKL/kwllVvU79/Ap0x 4nLPm7VSaag3tRiZil5Z2Zig1vJL4pz6XaxSLWKbfVIYfkGsS7HQo4uyB3uPWfqC5+X+ jcttuwZA3WaSfl/k7fHrv/bylp+IeeUYPqrjQwMMvS5GN7G3P2PtMhdCvHcNVh8j90uh 8kVg== X-Gm-Message-State: APzg51DrHBrx/VZkzg96OPKS3Xx6GielRJJNcAHcYCqSZ9L0PwNRJqPP 9gW49qTd3xMwx1b3UdyaFl5LOPjDdNndiGIM2HIrs40/SoT2JX0niRCDDOsrSvtzoHIV4yzRG7K StZMIUU6HjlOAk/d/AaWhe6mPFos370Dwvp5LnYG5LWAAmjH0IaqXg9iyg15DINowHg== X-Received: by 2002:a5d:4c45:: with SMTP id n5-v6mr10345766wrt.71.1534952818010; Wed, 22 Aug 2018 08:46:58 -0700 (PDT) X-Google-Smtp-Source: ANB0Vda+rnGr1RkWh0K4Asb3a0cXysXbi5dp4cdehMayKVzRzDqe5w5UHwp49FaXvmCy61GMXPBz X-Received: by 2002:a5d:4c45:: with SMTP id n5-v6mr10345742wrt.71.1534952817341; Wed, 22 Aug 2018 08:46:57 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1534952817; cv=none; d=google.com; s=arc-20160816; b=H/e8bRJOtj5fnx1F7I8i5WMHkZe+b1eUFUqbXv5rX2fCHEjFIvpeH1Zxdg4TwIAykH OQNOoNNGpkkGO2Oi0TupqjNSXyFmGprj5MsWhMG+dYoXiqOvgTdPvdKcCOL/1/kLHEcv P26OLlarzVmHkRAPXjEOV2hzU/BeRhzbfzW2Hn1KJyM5Ds/h+lz1XZPwNIQV6/bwpgT9 qJ2TgJxb6QsYSqfCrirKt5O3KPcodkOdnxiJ9dBquTdnJ35ueE/PF8fTYPOQ9elIVMk5 28eIEbNiLSdx2FCRLcEVk4LbKpCkfs/cyqAU3sbaZbBbcTMH29UZZ1CEWNgqzD5f3zRp u/jQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:references:subject:cc:to:from:date:user-agent :message-id:dkim-signature:arc-authentication-results; bh=DtDo4cQQlYpJctQYVAg287e1LDGKHg+PXr5W1nBz53Q=; b=pOhdpyBJUelPKQwYM7LUbs7ScEUXtyv1OY0wvCRk1830MIjnokMb13U53M8LnekHG0 n21He4nHGhKqS+a29Aw91nqkTyWW7hmNswBIYcH8nzm5IeXP7FMikRENCgIwKfytJqBW DS4zn+MZdFGRnSgLvfsV5VGHqR0S570F6THUWHDa3ioNWxbjNrs0KWVG/2+0a/Q5A9uJ KpPF1VOy3f/AojoUDCXT+xRgWvglbNb7/yXtKaUKsR/3boXC34+1WgYFJ6Yx+BRQjint zmy/3/ULs1iKUmVgw8up1vQwYdl3PmCLWDUtUkIH+o8zcEhrdEwK6UuC0k5uqvzBkPJ8 WXuQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@infradead.org header.s=merlin.20170209 header.b=AOQ8g0mF; spf=pass (google.com: best guess record for domain of peterz@infradead.org designates 2001:8b0:10b:1231::1 as permitted sender) smtp.mailfrom=peterz@infradead.org Received: from merlin.infradead.org (merlin.infradead.org. [2001:8b0:10b:1231::1]) by mx.google.com with ESMTPS id 64-v6si1699618wrf.122.2018.08.22.08.46.57 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 22 Aug 2018 08:46:57 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of peterz@infradead.org designates 2001:8b0:10b:1231::1 as permitted sender) client-ip=2001:8b0:10b:1231::1; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=merlin.20170209 header.b=AOQ8g0mF; spf=pass (google.com: best guess record for domain of peterz@infradead.org designates 2001:8b0:10b:1231::1 as permitted sender) smtp.mailfrom=peterz@infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-ID:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=DtDo4cQQlYpJctQYVAg287e1LDGKHg+PXr5W1nBz53Q=; b=AOQ8g0mFgDBL61alQiOuAyiDxh qqZq25A0DVaTD3yaYdSTSnEDjNmpw0WdTTRf42Yi9IMBX8j/O8lpk+AayLo6D9dDe+iH5JhnxZ493 n6VTifk+gF+9jwc27RckF1whb4ZVc+IeVJG8kM9iDdrgQm+ziYX/zSh/eevlYCzpJehiC0/bRWylx CijMfNi6t4TBllQhy81e3Q/O3jHPowDI55bNlkEQL3vX9BOVDqW0YR/7Q5fd5r+R7Sh1HL/pIxxjl 9NDmWTQcaIu8MgUCci7y134gKJUW+NxpVCNo+KYqZdwHk88xq56AM1Fu6KzbbA3NBBZ8GGuwFTalr ZOjj6vsg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fsVKN-0000WT-Ig; Wed, 22 Aug 2018 15:45:47 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id BD93D2024D723; Wed, 22 Aug 2018 17:45:44 +0200 (CEST) Message-ID: <20180822154046.772017055@infradead.org> User-Agent: quilt/0.65 Date: Wed, 22 Aug 2018 17:30:14 +0200 From: Peter Zijlstra To: torvalds@linux-foundation.org Cc: peterz@infradead.org, luto@kernel.org, x86@kernel.org, bp@alien8.de, will.deacon@arm.com, 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: [PATCH 2/4] mm/tlb: Remove tlb_remove_table() non-concurrent condition References: <20180822153012.173508681@infradead.org> MIME-Version: 1.0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP 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) Acked-by: Will Deacon --- mm/memory.c | 9 --------- 1 file changed, 9 deletions(-) --- a/mm/memory.c +++ b/mm/memory.c @@ -375,15 +375,6 @@ 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) {