LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Ingo Molnar <mingo@kernel.org>
To: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>,
	Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
	X86 ML <x86@kernel.org>, Borislav Petkov <bp@alien8.de>,
	Neil Berrington <neil.berrington@datacore.com>,
	LKML <linux-kernel@vger.kernel.org>,
	stable <stable@vger.kernel.org>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH v2 1/2] x86/mm/64: Fix vmapped stack syncing on very-large-memory 4-level systems
Date: Fri, 26 Jan 2018 10:30:07 +0100
Message-ID: <20180126093006.n55q4dkkrexymsji@gmail.com> (raw)
In-Reply-To: <CALCETrVwJCL=QTRT70b8u3p8xOXUiC7_Mkz45Bi3M9-vYgXWtg@mail.gmail.com>

* Andy Lutomirski <luto@kernel.org> 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

  reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-25 21:12 [PATCH v2 0/2] x86/mm/64: vmalloc pgd synchronization cleanups/fixes Andy Lutomirski
2018-01-25 21:12 ` [PATCH v2 1/2] x86/mm/64: Fix vmapped stack syncing on very-large-memory 4-level systems Andy Lutomirski
2018-01-25 21:49   ` Dave Hansen
2018-01-25 22:00     ` Andy Lutomirski
2018-01-26  9:30       ` Ingo Molnar [this message]
2018-01-26 18:54       ` Kirill A. Shutemov
2018-01-26 15:06   ` [tip:x86/urgent] " tip-bot for Andy Lutomirski
2018-01-26 18:51   ` [PATCH v2 1/2] " Kirill A. Shutemov
2018-01-26 19:02     ` Andy Lutomirski
2018-01-26 20:50       ` Kirill A. Shutemov
2018-01-25 21:12 ` [PATCH v2 2/2] x86/mm/64: Tighten up vmalloc_fault() sanity checks on 5-level kernels Andy Lutomirski
2018-01-26 15:07   ` [tip:x86/urgent] " tip-bot for Andy Lutomirski

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180126093006.n55q4dkkrexymsji@gmail.com \
    --to=mingo@kernel.org \
    --cc=bp@alien8.de \
    --cc=dave.hansen@intel.com \
    --cc=khlebnikov@yandex-team.ru \
    --cc=kirill.shutemov@linux.intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@kernel.org \
    --cc=neil.berrington@datacore.com \
    --cc=stable@vger.kernel.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
	git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git
	git clone --mirror https://lore.kernel.org/lkml/9 lkml/git/9.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git