Messages in this thread | | | Date | Thu, 17 Nov 2005 15:52:30 -0800 (PST) | Subject | Re: [PATCH 07/11] unpaged: COW on VM_UNPAGED | From | "David S. Miller" <> |
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From: Hugh Dickins <hugh@veritas.com> Date: Thu, 17 Nov 2005 19:37:23 +0000 (GMT)
> Remove the BUG_ON(vma->vm_flags & VM_UNPAGED) from do_wp_page, and let > it do Copy-On-Write without touching the VM_UNPAGED's page counts - but > this is incomplete, because the anonymous page it inserts will itself > need to be handled, here and in other functions - next patch. > > We still don't copy the page if the pfn is invalid, because the > copy_user_highpage interface does not allow it. But that's not been > a problem in the past: can be added in later if the need arises. > > Signed-off-by: Hugh Dickins <hugh@veritas.com>
Do we even need this? It is a very serious question...
The cases I've seen, and am aware of, I documented in a previous mail and those involve MAP_PRIVATE maps of /dev/mem or other similar fixed page mapping devices.
Which case truly needs COW faults on VM_RESERVED memory which isn't an application bug of some sort? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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