linux-fsdevel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Matthew Wilcox <willy@infradead.org>
To: Boaz Harrosh <boazh@netapp.com>
Cc: Jeff Moyer <jmoyer@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Rik van Riel <riel@redhat.com>, Jan Kara <jack@suse.cz>,
	Matthew Wilcox <mawilcox@microsoft.com>,
	Amit Golander <Amit.Golander@netapp.com>
Subject: Re: [PATCH] mm: Add new vma flag VM_LOCAL_CPU
Date: Mon, 14 May 2018 12:15:51 -0700	[thread overview]
Message-ID: <20180514191551.GA27939@bombadil.infradead.org> (raw)
In-Reply-To: <0efb5547-9250-6b6c-fe8e-cf4f44aaa5eb@netapp.com>

On Mon, May 14, 2018 at 08:28:01PM +0300, Boaz Harrosh wrote:
> On a call to mmap an mmap provider (like an FS) can put
> this flag on vma->vm_flags.
> 
> The VM_LOCAL_CPU flag tells the Kernel that the vma will be used
> from a single-core only, and therefore invalidation (flush_tlb) of
> PTE(s) need not be a wide CPU scheduling.

I still don't get this.  You're opening the kernel up to being exploited
by any application which can persuade it to set this flag on a VMA.

> NOTE: This vma (VM_LOCAL_CPU) is never used during a page_fault. It is
> always used in a synchronous way from a thread pinned to a single core.

It's not a question of how your app is going to use this flag.  It's a
question about how another app can abuse this flag (or how your app is
going to be exploited to abuse this flag) to break into the kernel.

  parent reply	other threads:[~2018-05-14 19:15 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-14 17:28 [PATCH] mm: Add new vma flag VM_LOCAL_CPU Boaz Harrosh
2018-05-14 18:26 ` Boaz Harrosh
2018-05-15  7:08   ` Christoph Hellwig
2018-05-15 10:45     ` Boaz Harrosh
2018-05-14 19:15 ` Matthew Wilcox [this message]
2018-05-14 19:37   ` Boaz Harrosh
2018-05-15  0:41     ` Matthew Wilcox
2018-05-15 10:43       ` Boaz Harrosh
2018-05-15 11:11         ` Matthew Wilcox
2018-05-15 11:41           ` Boaz Harrosh
2018-05-15 12:03             ` Matthew Wilcox
2018-05-15 13:29               ` Boaz Harrosh
2018-05-15 13:50                 ` Matthew Wilcox
2018-05-15 14:10                   ` Boaz Harrosh
2018-05-15 14:18                     ` Matthew Wilcox
2018-05-15 14:30                       ` Boaz Harrosh
2018-05-15 12:09             ` Peter Zijlstra
2018-05-15 12:31               ` Boaz Harrosh
2018-05-15 11:47         ` Peter Zijlstra
2018-05-15 12:01           ` Boaz Harrosh
2018-05-15 12:07         ` Mark Rutland
2018-05-15 12:35           ` Peter Zijlstra
2018-05-15 13:19           ` Boaz Harrosh
2018-05-18 14:14         ` Christopher Lameter
2018-05-22 16:05           ` Boaz Harrosh
2018-05-22 16:18             ` Dave Hansen
2018-05-22 16:46               ` Christopher Lameter
2018-05-22 16:56                 ` Peter Zijlstra
2018-05-22 17:03                 ` Dave Hansen
2018-05-22 17:35                   ` Christopher Lameter
2018-05-22 17:51                   ` Matthew Wilcox
2018-05-23 17:30                     ` Dave Hansen
2018-05-23 17:46                       ` Nadav Amit
2018-05-23 18:10             ` Mark Rutland
2018-05-14 21:49 ` Andrew Morton
2018-05-15  0:44   ` Matthew Wilcox
2018-05-15 11:54     ` Boaz Harrosh
2018-05-15 13:24       ` Boaz Harrosh
2018-05-15 14:17       ` Peter Zijlstra
2018-05-15 14:36         ` Boaz Harrosh
2018-05-15 14:19 ` Dave Hansen

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=20180514191551.GA27939@bombadil.infradead.org \
    --to=willy@infradead.org \
    --cc=Amit.Golander@netapp.com \
    --cc=akpm@linux-foundation.org \
    --cc=boazh@netapp.com \
    --cc=dave.hansen@linux.intel.com \
    --cc=hpa@zytor.com \
    --cc=jack@suse.cz \
    --cc=jmoyer@redhat.com \
    --cc=kirill.shutemov@linux.intel.com \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mawilcox@microsoft.com \
    --cc=mingo@redhat.com \
    --cc=peterz@infradead.org \
    --cc=riel@redhat.com \
    --cc=tglx@linutronix.de \
    --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
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).