From: Michal Hocko <mhocko@kernel.org>
To: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>,
Joel Stanley <joel@jms.id.au>,
Stephen Rothwell <sfr@canb.auug.org.au>,
Andrew Morton <akpm@linux-foundation.org>,
Linux-Next Mailing List <linux-next@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Russell King <linux@armlinux.org.uk>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Abdul Haleem <abdhalee@linux.vnet.ibm.com>,
Ralf Baechle <ralf@linux-mips.org>,
"James E.J. Bottomley" <jejb@parisc-linux.org>,
Helge Deller <deller@gmx.de>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Rich Felker <dalias@libc.org>,
"David S. Miller" <davem@davemloft.net>,
Chris Zankel <chris@zankel.net>,
Max Filippov <jcmvbkbc@gmail.com>,
linux-arm-kernel@lists.infradead.org, linuxppc-dev@lis
Subject: Re: linux-next: Tree for Nov 7
Date: Tue, 14 Nov 2017 08:07:48 +0100 [thread overview]
Message-ID: <20171114070748.in5zdc4giqbxowjy@dhcp22.suse.cz> (raw)
In-Reply-To: <c52fa249-9583-18a2-cbac-28abfb23d5a5@oracle.com>
On Mon 13-11-17 09:35:22, Khalid Aziz wrote:
> On 11/13/2017 09:06 AM, Michal Hocko wrote:
> > OK, so this one should take care of the backward compatibility while
> > still not touching the arch code
> > ---
> > commit 39ff9bf8597e79a032da0954aea1f0d77d137765
> > Author: Michal Hocko <mhocko@suse.com>
> > Date: Mon Nov 13 17:06:24 2017 +0100
> >
> > mm: introduce MAP_FIXED_SAFE
> > MAP_FIXED is used quite often but it is inherently dangerous because it
> > unmaps an existing mapping covered by the requested range. While this
> > might be might be really desidered behavior in many cases there are
> > others which would rather see a failure than a silent memory corruption.
> > Introduce a new MAP_FIXED_SAFE flag for mmap to achive this behavior.
> > It is a MAP_FIXED extension with a single exception that it fails with
> > ENOMEM if the requested address is already covered by an existing
> > mapping. We still do rely on get_unmaped_area to handle all the arch
> > specific MAP_FIXED treatment and check for a conflicting vma after it
> > returns.
> > Signed-off-by: Michal Hocko <mhocko@suse.com>
> >
> > ...... deleted .......
> > diff --git a/mm/mmap.c b/mm/mmap.c
> > index 680506faceae..aad8d37f0205 100644
> > --- a/mm/mmap.c
> > +++ b/mm/mmap.c
> > @@ -1358,6 +1358,10 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
> > if (mm->map_count > sysctl_max_map_count)
> > return -ENOMEM;
> > + /* force arch specific MAP_FIXED handling in get_unmapped_area */
> > + if (flags & MAP_FIXED_SAFE)
> > + flags |= MAP_FIXED;
> > +
> > /* Obtain the address to map to. we verify (or select) it and ensure
> > * that it represents a valid section of the address space.
> > */
>
> Do you need to move this code above:
>
> if (!(flags & MAP_FIXED))
> addr = round_hint_to_min(addr);
>
> /* Careful about overflows.. */
> len = PAGE_ALIGN(len);
> if (!len)
> return -ENOMEM;
>
> Not doing that might mean the hint address will end up being rounded for
> MAP_FIXED_SAFE which would change the behavior from MAP_FIXED.
Yes, I will move it.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2017-11-14 7:07 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-07 5:22 linux-next: Tree for Nov 7 Stephen Rothwell
2017-11-07 22:22 ` Joel Stanley
2017-11-08 14:20 ` Michal Hocko
2017-11-10 12:30 ` Michal Hocko
2017-11-12 1:08 ` Joel Stanley
2017-11-13 9:20 ` Michal Hocko
2017-11-13 9:34 ` Russell King - ARM Linux
2017-11-13 9:42 ` Michal Hocko
2017-11-13 11:34 ` Michael Ellerman
2017-11-13 12:00 ` Michal Hocko
2017-11-13 15:16 ` Michal Hocko
2017-11-13 15:48 ` Russell King - ARM Linux
2017-11-13 15:59 ` Michal Hocko
2017-11-13 15:49 ` Michal Hocko
2017-11-13 16:06 ` Michal Hocko
2017-11-13 16:35 ` Khalid Aziz
2017-11-14 7:07 ` Michal Hocko [this message]
2017-11-14 9:18 ` Michael Ellerman
2017-11-14 9:29 ` Michal Hocko
2017-11-14 9:02 ` Michael Ellerman
2017-11-14 8:54 ` Michael Ellerman
2017-11-14 9:04 ` Michal Hocko
2017-11-14 14:52 ` Khalid Aziz
2017-11-13 14:11 ` Michal Hocko
2017-11-13 15:09 ` Russell King - ARM Linux
2017-11-13 15:31 ` Michal Hocko
2017-11-14 0:03 ` Andrew Morton
2017-11-14 0:36 ` Stephen Rothwell
-- strict thread matches above, loose matches on Subject: below --
2023-11-07 1:17 Stephen Rothwell
2022-11-07 3:44 Stephen Rothwell
2019-11-07 8:07 Stephen Rothwell
2018-11-07 3:16 Stephen Rothwell
2013-11-07 7:31 Stephen Rothwell
2012-11-07 5:15 Stephen Rothwell
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