From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Hugh Dickins <hughd@google.com>,
Ingo Korb <ingo.korb@tu-dortmund.de>, Ning Qu <quning@google.com>,
Dave Jones <davej@redhat.com>,
Sasha Levin <sasha.levin@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: PROBLEM: repeated remap_file_pages on tmpfs triggers bug on process exit
Date: Tue, 15 Jul 2014 14:54:56 +0300 (EEST) [thread overview]
Message-ID: <20140715115456.32886E00A3@blue.fi.intel.com> (raw)
In-Reply-To: <CALYGNiM3tQUCvSPxPbum5jkhNOPeKpAVL=x3ggFmZH-QaqULcA@mail.gmail.com>
Konstantin Khlebnikov wrote:
> On Tue, Jul 15, 2014 at 2:55 PM, Kirill A. Shutemov
> <kirill.shutemov@linux.intel.com> wrote:
> > Konstantin Khlebnikov wrote:
> >> It seems boundng logic in do_fault_around is wrong:
> >>
> >> start_addr = max(address & fault_around_mask(), vma->vm_start);
> >> off = ((address - start_addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
> >> pte -= off;
> >> pgoff -= off;
> >>
> >> Ok, off <= 511, but it might be bigger than pte offset in pte table.
> >
> > I don't see how it possible: fault_around_mask() cannot be more than 0x1ff000
> > (x86-64, fault_around_bytes == 2M). It means start_addr will be aligned to 2M
> > boundary in this case which is start of the page table pte belong to.
> >
> > Do I miss something?
>
> Nope, you're right. This fixes kernel crash but not the original problem.
>
> Problem is caused by calling do_fault_around for _non-linear_ faiult.
> In this case pgoff is shifted and might become negative during calculation.
> I'll send another patch.
I've got to the same conclusion. My patch is below.
next prev parent reply other threads:[~2014-07-15 11:55 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-14 12:58 Ingo Korb
2014-07-14 19:22 ` Hugh Dickins
2014-07-14 20:13 ` Konstantin Khlebnikov
2014-07-15 9:55 ` [PATCH] mm: fix faulting range in do_fault_around Konstantin Khlebnikov
2014-07-15 10:55 ` PROBLEM: repeated remap_file_pages on tmpfs triggers bug on process exit Kirill A. Shutemov
2014-07-15 11:33 ` Konstantin Khlebnikov
2014-07-15 11:54 ` Kirill A. Shutemov [this message]
2014-07-15 20:46 ` Hugh Dickins
2014-07-15 11:58 ` [PATCH] mm: do not call do_fault_around for non-linear fault Konstantin Khlebnikov
2014-07-15 15:29 ` Ingo Korb
2014-07-15 20:42 ` Andrew Morton
2014-07-15 21:07 ` Konstantin Khlebnikov
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=20140715115456.32886E00A3@blue.fi.intel.com \
--to=kirill.shutemov@linux.intel.com \
--cc=akpm@linux-foundation.org \
--cc=davej@redhat.com \
--cc=hughd@google.com \
--cc=ingo.korb@tu-dortmund.de \
--cc=koct9i@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=quning@google.com \
--cc=sasha.levin@oracle.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