From: Rik van Riel <riel@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, mhocko@kernel.org,
mike.kravetz@oracle.com, linux-mm@kvack.org, fweimer@redhat.com,
colm@allcosts.net, keescook@chromium.org, luto@amacapital.net,
wad@chromium.org, mingo@kernel.org, kirill@shutemov.name,
dave.hansen@intel.com, linux-api@vger.kernel.org,
torvalds@linux-foundation.org, willy@infradead.org
Subject: Re: [PATCH 2/2] mm,fork: introduce MADV_WIPEONFORK
Date: Tue, 15 Aug 2017 22:18:19 -0400 [thread overview]
Message-ID: <1502849899.6577.66.camel@redhat.com> (raw)
In-Reply-To: <20170815155114.ff9f4164eed28bf02db48fbb@linux-foundation.org>
On Tue, 2017-08-15 at 15:51 -0700, Andrew Morton wrote:
> On Fri, 11 Aug 2017 17:28:29 -0400 riel@redhat.com wrote:
>
> > A further complication is the proliferation of clone flags,
> > programs bypassing glibc's functions to call clone directly,
> > and programs calling unshare, causing the glibc pthread_atfork
> > hook to not get called.
> >
> > It would be better to have the kernel take care of this
> > automatically.
>
> I'll add "The patch also adds MADV_KEEPONFORK, to undo the effects of
> a
> prior MADV_WIPEONFORK." here.
>
> I guess it isn't worth mentioning that these things can cause VMA
> merges and splits.
That's the same as every other Linux specific madvise operation.
> > --- a/mm/madvise.c
> > +++ b/mm/madvise.c
> > @@ -80,6 +80,17 @@ static long madvise_behavior(struct
> > vm_area_struct *vma,
> > }
> > new_flags &= ~VM_DONTCOPY;
> > break;
> > + case MADV_WIPEONFORK:
> > + /* MADV_WIPEONFORK is only supported on anonymous
> > memory. */
> > + if (vma->vm_file || vma->vm_flags & VM_SHARED) {
> > + error = -EINVAL;
> > + goto out;
> > + }
> > + new_flags |= VM_WIPEONFORK;
> > + break;
> > + case MADV_KEEPONFORK:
> > + new_flags &= ~VM_WIPEONFORK;
> > + break;
> > case MADV_DONTDUMP:
> > new_flags |= VM_DONTDUMP;
> > break;
>
> It seems odd to permit MADV_KEEPONFORK against other-than-anon vmas?
Given that the only way to set VM_WIPEONFORK is through
MADV_WIPEONFORK, calling MADV_KEEPONFORK on an
other-than-anon vma would be equivalent to a noop.
If new_flags == vma->vm_flags, madvise_behavior() will
immediately exit.
next prev parent reply other threads:[~2017-08-16 2:18 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-11 21:28 [PATCH v4 0/2] mm,fork,security: introduce MADV_WIPEONFORK riel
2017-08-11 21:28 ` [PATCH 1/2] x86,mpx: make mpx depend on x86-64 to free up VMA flag riel
2017-08-11 21:28 ` [PATCH 2/2] mm,fork: introduce MADV_WIPEONFORK riel
2017-08-15 22:51 ` Andrew Morton
2017-08-16 2:18 ` Rik van Riel [this message]
2017-08-17 22:50 ` Andrew Morton
2017-08-18 16:28 ` Rik van Riel
2017-08-18 18:15 ` Andrew Morton
2017-08-19 0:02 ` Rik van Riel
2017-08-18 17:25 ` Mike Kravetz
-- strict thread matches above, loose matches on Subject: below --
2017-08-11 19:19 [PATCH v3 0/2] mm,fork,security: " riel
2017-08-11 19:19 ` [PATCH 2/2] mm,fork: " riel
2017-08-11 19:42 ` Linus Torvalds
2017-08-11 20:27 ` Rik van Riel
2017-08-11 20:50 ` Linus Torvalds
2017-08-06 14:04 [PATCH v2 0/2] mm,fork,security: " riel
2017-08-06 14:04 ` [PATCH 2/2] mm,fork: " riel
2017-08-10 15:23 ` Michal Hocko
2017-08-11 15:23 ` Rik van Riel
2017-08-11 16:36 ` Mike Kravetz
2017-08-11 16:59 ` Rik van Riel
2017-08-11 17:07 ` Mike Kravetz
2017-08-04 19:07 [PATCH 0/2] mm,fork,security: " riel
2017-08-04 19:07 ` [PATCH 2/2] mm,fork: " riel
2017-08-04 23:09 ` Mike Kravetz
2017-08-05 14:05 ` Rik van Riel
2017-08-14 15:45 ` kbuild test robot
2017-08-04 19:01 [PATCH 0/2] mm,fork: MADV_WIPEONFORK - an empty VMA in the child riel
2017-08-04 19:01 ` [PATCH 2/2] mm,fork: introduce MADV_WIPEONFORK riel
2017-08-05 18:46 ` kbuild test robot
2017-08-05 19:33 ` kbuild test robot
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