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[209.132.180.67]) by mx.google.com with ESMTP id s9-v6si2111474pfm.85.2018.07.20.10.07.52; Fri, 20 Jul 2018 10:08:08 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=v3s23Plf; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388025AbeGTR41 (ORCPT + 99 others); Fri, 20 Jul 2018 13:56:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:55278 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731939AbeGTR41 (ORCPT ); Fri, 20 Jul 2018 13:56:27 -0400 Received: from mail-wr1-f44.google.com (mail-wr1-f44.google.com [209.85.221.44]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5241E20858 for ; Fri, 20 Jul 2018 17:07:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1532106436; bh=+pX2XRouS9SwWpu4ilvc/t4Fjx4URm7cKVPnPh2z8/8=; h=In-Reply-To:References:From:Date:Subject:To:Cc:From; b=v3s23Plf8n3vgWfginoABK+/I3Yrtf1sFncDddl+rpMVgiS9oNRKYoBfSjhj5exje wP+nau5Dqjffi530+TxgOrEQP5kL2t5b6V/+2gj6hicy9Msosx4GDrlMAtPCKw3pgg 5dn7IyvNxxoMIdXbBtZ66MoEIkLJAVYR99B5Auf4= Received: by mail-wr1-f44.google.com with SMTP id a3-v6so11957451wrt.2 for ; Fri, 20 Jul 2018 10:07:16 -0700 (PDT) X-Gm-Message-State: AOUpUlGG4/2IO+KJWs4BDaQ2nx6zlvQMpMcdDXa6yx+f3xsn68+LXUQj y8+RHcNOfiGpCdV2RIQKCAZF4eGv5A07Y3GjXwbHAQ== X-Received: by 2002:adf:fe42:: with SMTP id m2-v6mr1984651wrs.171.1532106434752; Fri, 20 Jul 2018 10:07:14 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:a1c:d548:0:0:0:0:0 with HTTP; Fri, 20 Jul 2018 10:06:54 -0700 (PDT) In-Reply-To: <1532103744-31902-2-git-send-email-joro@8bytes.org> References: <1532103744-31902-1-git-send-email-joro@8bytes.org> <1532103744-31902-2-git-send-email-joro@8bytes.org> From: Andy Lutomirski Date: Fri, 20 Jul 2018 10:06:54 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 1/3] perf/core: Make sure the ring-buffer is mapped in all page-tables To: Joerg Roedel Cc: Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , X86 ML , LKML , Linux-MM , Linus Torvalds , Andy Lutomirski , Dave Hansen , Josh Poimboeuf , Juergen Gross , Peter Zijlstra , Borislav Petkov , Jiri Kosina , Boris Ostrovsky , Brian Gerst , David Laight , Denys Vlasenko , Eduardo Valentin , Greg KH , Will Deacon , "Liguori, Anthony" , Daniel Gruss , Hugh Dickins , Kees Cook , Andrea Arcangeli , Waiman Long , Pavel Machek , "David H . Gutteridge" , Joerg Roedel , Arnaldo Carvalho de Melo , Alexander Shishkin , Jiri Olsa , Namhyung Kim 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 > On Jul 20, 2018, at 6:22 AM, Joerg Roedel wrote: > > From: Joerg Roedel > > The ring-buffer is accessed in the NMI handler, so we better > avoid faulting on it. Sync the vmalloc range with all > page-tables in system to make sure everyone has it mapped. > > This fixes a WARN_ON_ONCE() that can be triggered with PTI > enabled on x86-32: > > WARNING: CPU: 4 PID: 0 at arch/x86/mm/fault.c:320 vmalloc_fault+0x220/0x230 > > This triggers because with PTI enabled on an PAE kernel the > PMDs are no longer shared between the page-tables, so the > vmalloc changes do not propagate automatically. It seems like it would be much more robust to fix the vmalloc_fault() code instead.