From: "Michael S. Tsirkin" <mst@mellanox.co.il>
To: Linus Torvalds <torvalds@osdl.org>
Cc: Hugh Dickins <hugh@veritas.com>,
Gleb Natapov <gleb@minantech.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Petr Vandrovec <vandrove@vc.cvut.cz>,
Nick Piggin <nickpiggin@yahoo.com.au>,
Badari Pulavarty <pbadari@us.ibm.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
openib-general@openib.org
Subject: Re: madvise MADV_DONTFORK/MADV_DOFORK
Date: Mon, 13 Feb 2006 21:20:46 +0200 [thread overview]
Message-ID: <20060213192046.GD12458@mellanox.co.il> (raw)
In-Reply-To: <Pine.LNX.4.64.0602131104460.3691@g5.osdl.org>
Quoting Linus Torvalds <torvalds@osdl.org>:
> >
> > Add madvise options to control whether memory range is inherited across fork.
> > Useful e.g. for when hardware is doing DMA from/into these pages.
> >
> > Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
> >
> > - if (mpnt->vm_flags & VM_DONTCOPY) {
> > + if (mpnt->vm_flags & (VM_DONTCOPY | VM_DONTFORK)) {
>
> Why?
>
> That VM_DONTCOPY _is_ DONTFORK.
>
> Don't add a new useless DONTFORK that doesn't have any value.
When this was last discussed, Hugh Dickins said:
> If a driver sets VM_DONTCOPY, it's likely to be because the driver knows it'll
> cause some nastiness (memory corruption, memory leak, lockup...) if it were
> copied. The memory belongs to the driver, it's letting the process have a
> window on it. I don't think we should now let the process overrule it.
Here's a pointer to the relevant discussion:
http://lkml.org/lkml/2005/11/3/112
--
Michael S. Tsirkin
Staff Engineer, Mellanox Technologies
prev parent reply other threads:[~2006-02-13 19:19 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-02-13 15:41 Michael S. Tsirkin
2006-02-13 18:23 ` Hugh Dickins
2006-02-13 19:02 ` Michael S. Tsirkin
2006-02-14 6:51 ` Gleb Natapov
2006-02-13 19:04 ` [openib-general] " Roland Dreier
2006-02-13 19:05 ` Linus Torvalds
2006-02-13 19:16 ` [openib-general] " Roland Dreier
2006-02-13 19:34 ` Linus Torvalds
2006-02-13 19:50 ` Hugh Dickins
2006-02-13 21:09 ` Michael S. Tsirkin
2006-02-13 21:57 ` Hugh Dickins
2006-02-13 22:09 ` Michael S. Tsirkin
2006-02-13 22:54 ` Hugh Dickins
2006-02-13 23:01 ` [PATCH] " Michael S. Tsirkin
2006-02-13 23:44 ` Hugh Dickins
2006-02-13 22:27 ` [openib-general] " Linus Torvalds
2006-02-13 22:55 ` Michael S. Tsirkin
2006-02-13 23:01 ` Hugh Dickins
2006-02-13 23:35 ` [PATCH] " Michael S. Tsirkin
2006-02-15 4:31 ` Nick Piggin
2006-02-15 6:09 ` Roland Dreier
2006-02-15 6:16 ` Andrew Morton
2006-02-15 6:34 ` [PATCH] Fix up MADV_DONTFORK/MADV_DOFORK definitions Roland Dreier
2006-02-15 6:48 ` Gleb Natapov
2006-02-15 7:06 ` Nick Piggin
2006-02-15 7:31 ` Bernd Eckenfels
2006-02-15 8:18 ` Michael S. Tsirkin
2006-02-15 8:13 ` [PATCH] madvise MADV_DONTFORK/MADV_DOFORK Michael S. Tsirkin
2006-02-13 20:05 ` Michael S. Tsirkin
2006-02-13 19:20 ` Michael S. Tsirkin [this message]
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