From: Roland Dreier <roland@topspin.com>
To: Manfred Spraul <manfred@colorfullife.com>
Cc: Eli Cohen <mlxk@mellanox.co.il>, linux-kernel@vger.kernel.org
Subject: Re: locking user space memory in kernel
Date: 21 Mar 2004 08:40:37 -0800 [thread overview]
Message-ID: <52u10i2lx6.fsf@topspin.com> (raw)
In-Reply-To: <405D7D2F.9050507@colorfullife.com>
Manfred> I think just get_user_pages() should be sufficient: the
Manfred> pages won't be swapped out. You don't need to set
Manfred> VM_LOCKED in vma->vm_flags to prevent the swap out. In
Manfred> the worst case, the pte is cleared a that will cause a
Manfred> soft page fault, but the physical address won't
Manfred> change. Multiple get_user_pages() calls on overlapping
Manfred> regions are ok, the page count is an atomic_t, at least
Manfred> 24-bit large.
There is one case that we ran into where the physical address can
change: if a process does a fork() and then triggers COW.
- Roland
next prev parent reply other threads:[~2004-03-21 16:40 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-03-21 11:31 locking user space memory in kernel Manfred Spraul
2004-03-21 14:12 ` Manfred Spraul
2004-03-21 16:40 ` Roland Dreier [this message]
2004-03-21 17:15 ` Manfred Spraul
2004-03-21 18:18 ` Roland Dreier
2004-03-22 13:15 ` Eli Cohen
2004-03-22 15:22 ` Eli Cohen
2004-03-22 19:34 ` Manfred Spraul
-- strict thread matches above, loose matches on Subject: below --
2004-04-08 6:20 Ross Dickson
2004-04-08 0:45 Libor Michalek
2004-04-08 5:22 ` Manfred Spraul
2004-03-21 11:18 Eli Cohen
2004-03-21 11:35 ` Arjan van de Ven
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