GitHub-Mirror/Star64_linux
2
0
Fork 0
mirror of https://github.com/Fishwaldo/Star64_linux.git synced 2025-06-20 05:31:15 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

[PATCH] unpaged: anon in VM_UNPAGED

Browse source 
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>
This commit is contained in:
Hugh Dickins 2005-11-21 21:32:18 -08:00 • committed by Linus Torvalds
parent 920fc356f5
commit ee498ed730
2 changed files with 46 additions and 24 deletions
Download patch file Download diff file Expand all files Collapse all files

7
mm/rmap.c
View file

@ -225,7 +225,9 @@ vma_address(struct page *page, struct vm_area_struct *vma)
/*
* At what user virtual address is page expected in vma? checking that the
* page matches the vma: currently only used by unuse_process, on anon pages.
* page matches the vma: currently only used on anon pages, by unuse_vma;
* and by extraordinary checks on anon pages in VM_UNPAGED vmas, taking
* care that an mmap of /dev/mem might window free and foreign pages.
*/
unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
{
@ -234,7 +236,8 @@ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
(void *)page->mapping - PAGE_MAPPING_ANON)
return -EFAULT;
} else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) {
if (vma->vm_file->f_mapping != page->mapping)
if (!vma->vm_file ||
vma->vm_file->f_mapping != page->mapping)
return -EFAULT;
} else
return -EFAULT;