From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-2313113-1516959027-2-15928818134670702552 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, FSL_HELO_FAKE 3.199, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='org', MailFrom='org' X-Spam-charsets: plain='us-ascii' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1516959026; b=aAdJZm+LCxppG/t2AsktsfI2IL3D0knrASKY/lS3fRovIRZ QfhhxMM7qncYhdM0tJfmhOFrf/Rt8YrdX304QAaYbvHY/N39DKguVSjZ6lrMCxX9 5skqbmAsoh5O5Vq75bg7DSsIQxlDSReMrfKM6ECG+hyBK+rO9ztOamGj7pkjdxfR lopb0B1znE0ds+ZSRKSnErMJjQAshU9915Nn8EuK5+hmy5n7TTm8kOfLioUuXXwZ 0w+eEKK4VrguQyBKUOCWD9hHP0VtpneXIC4EhggfPMVtn1gSrrbdHT2q1jB7vm61 CF7R3SMA+6Eb4aFEmTAP3TEmFjhM3I8w8O8T1jQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=date:from:to:cc:subject:message-id :references:mime-version:content-type:in-reply-to:sender :list-id; s=arctest; t=1516959026; bh=Z2MSog/IGhRvEkgBWclj9dZa1a erlCql9i7tBc65rT4=; b=KVKWBfbAVedqJfIU4xYR6C+L23/aZqe9o6BzbdJBLs ZIlUqwlQNn8zjAiau4GdV8utj/w1gjFXvxm0l1Qz/+iVhaKKbt1wr3X+B4+gWEZb RxVFaV9cyDt8Rfy4cmU19PpbKR8JVsHSPZ6u6v305FNIceQUZwL/V+WQFt/5fILp Qtay+q7LcjQb/7k0FNbEkhrNLWt7ZMfJLldygQwAmVbeKhQw3hHz8204/L1FOk/r 0buicHZMFRCsFjnFHnm+0/x+L1YysoEYS3BVNAfnOD5mrKu1ksGyEuGE8/IFuK2z IZuxyligdyT8zrGJjiYxt5KlYKrDR8u3eCmTKvN9NuHg== ARC-Authentication-Results: i=1; mx2.messagingengine.com; arc=none (no signatures found); dkim=fail (message has been altered; 2048-bit rsa key sha256) header.d=gmail.com header.i=@gmail.com header.b=TvPGB3RN x-bits=2048 x-keytype=rsa x-algorithm=sha256 x-selector=20161025; dmarc=none (p=none,has-list-id=yes,d=none) header.from=kernel.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=orgdomain_pass; x-google-dkim=fail (message has been altered; 2048-bit rsa key) header.d=1e100.net header.i=@1e100.net header.b=oPitz2r9; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=kernel.org header.result=pass header_is_org_domain=yes Authentication-Results: mx2.messagingengine.com; arc=none (no signatures found); dkim=fail (message has been altered; 2048-bit rsa key sha256) header.d=gmail.com header.i=@gmail.com header.b=TvPGB3RN x-bits=2048 x-keytype=rsa x-algorithm=sha256 x-selector=20161025; dmarc=none (p=none,has-list-id=yes,d=none) header.from=kernel.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=orgdomain_pass; x-google-dkim=fail (message has been altered; 2048-bit rsa key) header.d=1e100.net header.i=@1e100.net header.b=oPitz2r9; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=kernel.org header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752652AbeAZJaN (ORCPT ); Fri, 26 Jan 2018 04:30:13 -0500 Received: from mail-wm0-f67.google.com ([74.125.82.67]:35404 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752402AbeAZJaL (ORCPT ); Fri, 26 Jan 2018 04:30:11 -0500 X-Google-Smtp-Source: AH8x226M85DdTt9peSakgwy7lYxEE8jukEgkTLPom5tUgFE+wsmlRAGg0Gouj15EGuyGuSFStQPHLQ== Date: Fri, 26 Jan 2018 10:30:07 +0100 From: Ingo Molnar To: Andy Lutomirski Cc: Dave Hansen , Konstantin Khlebnikov , X86 ML , Borislav Petkov , Neil Berrington , LKML , stable , "Kirill A. Shutemov" Subject: Re: [PATCH v2 1/2] x86/mm/64: Fix vmapped stack syncing on very-large-memory 4-level systems Message-ID: <20180126093006.n55q4dkkrexymsji@gmail.com> References: <346541c56caed61abbe693d7d2742b4a380c5001.1516914529.git.luto@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170609 (1.8.3) Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: * Andy Lutomirski wrote: > What I'd really like to see is an entirely different API. Maybe: > > typedef struct { > opaque, but probably includes: > int depth; /* 0 is root */ > void *table; > } ptbl_ptr; > > ptbl_ptr root_table = mm_root_ptbl(mm); > > set_ptbl_entry(root_table, pa, prot); > > /* walk tables */ > ptbl_ptr pt = ...; > ptentry_ptr entry; > while (ptbl_has_children(pt)) { > pt = pt_next(pt, addr); > } > entry = pt_entry_at(pt, addr); > /* do something with entry */ > > etc. > > Now someone can add a sixth level without changing every code path in > the kernel that touches page tables. Iteration based page table lookups would be neat. A sixth level is unavoidable on x86-64 I think - we'll get there in a decade or so? The sixth level will also use up the last ~8 bits of virtual memory available on 64-bit. Thanks, Ingo