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Staging
v0.8.1
https://github.com/torvalds/linux
02 December 2023, 22:23:51 UTC
Revision ee498ed730283e9cdfc8913f12b90a2246f1a8cc authored by Hugh Dickins on 22 November 2005, 05:32:18 UTC, committed by Linus Torvalds on 22 November 2005, 17:13:42 UTC 
[PATCH] unpaged: anon in VM_UNPAGED
 
copy_one_pte needs to copy the anonymous COWed pages in a VM_UNPAGED area,
zap_pte_range needs to free them, do_wp_page needs to COW them: just like
ordinary pages, not like the unpaged.

But recognizing them is a little subtle: because PageReserved is no longer a
condition for remap_pfn_range, we can now mmap all of /dev/mem (whether the
distro permits, and whether it's advisable on this or that architecture, is
another matter).  So if we can see a PageAnon, it may not be ours to mess with
(or may be ours from elsewhere in the address space).  I suspect there's an
entertaining insoluble self-referential problem here, but the page_is_anon
function does a good practical job, and MAP_PRIVATE PROT_WRITE VM_UNPAGED will
always be an odd choice.

In updating the comment on page_address_in_vma, noticed a potential NULL
dereference, in a path we don't actually take, but fixed it.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1 parent 920fc35
History
Tip revision: ee498ed730283e9cdfc8913f12b90a2246f1a8cc authored by Hugh Dickins on 22 November 2005, 05:32:18 UTC
[PATCH] unpaged: anon in VM_UNPAGED
Tip revision: ee498ed
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