linux-mm.kvack.org archive mirror
 help / color / mirror / Atom feed
From: Andrew Morton <akpm@linux-foundation.org>
To: Robin Holt <holt@sgi.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
	linux-mm@kvack.org, Jack Steiner <steiner@sgi.com>
Subject: Re: [RFP 2/3] Fix unmap_vma() bug related to mmu_notifiers
Date: Fri, 29 Jan 2010 12:54:26 -0800	[thread overview]
Message-ID: <20100129125426.2cde0a5f.akpm@linux-foundation.org> (raw)
In-Reply-To: <20100128195634.355405000@alcatraz.americas.sgi.com>

On Thu, 28 Jan 2010 13:56:29 -0600
Robin Holt <holt@sgi.com> wrote:

> 
> unmap_vmas() can fail to correctly flush the TLB if a
> callout to mmu_notifier_invalidate_range_start() sleeps.
> The mmu_gather list is initialized prior to the callout. If it is reused
> while the thread is sleeping, the mm field may be invalid.
> 
> If the task migrates to a different cpu, the task may use the wrong
> mmu_gather.

I don't think that description is complete.

There might be ways in which we can prevent this task from being
migrated to another CPU, but that doesn't fix the problem because the
mmu_gather is a per-CPU resource and might get trashed if another task
is scheduled on THIS cpu, and uses its mmu_gather.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

  reply	other threads:[~2010-01-29 20:55 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-01-28 19:56 [RFP 0/3] Make mmu_notifier_invalidate_range_start able to sleep Robin Holt
2010-01-28 19:56 ` [RFP 1/3] srcu Robin Holt
2010-01-29 20:56   ` Andrew Morton
2010-02-01 19:06     ` Robin Holt
2010-01-28 19:56 ` [RFP 2/3] Fix unmap_vma() bug related to mmu_notifiers Robin Holt
2010-01-29 20:54   ` Andrew Morton [this message]
2010-02-01 19:07     ` Robin Holt
2010-01-28 19:56 ` [RFP 3/3] Make mmu_notifier_invalidate_range_start able to sleep Robin Holt
2010-01-28 21:31   ` Andrea Arcangeli
2010-01-29 12:37     ` Robin Holt
2010-01-29 21:08   ` Andrew Morton
2010-02-01 19:22     ` Robin Holt

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=20100129125426.2cde0a5f.akpm@linux-foundation.org \
    --to=akpm@linux-foundation.org \
    --cc=aarcange@redhat.com \
    --cc=holt@sgi.com \
    --cc=linux-mm@kvack.org \
    --cc=steiner@sgi.com \
    /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).