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[PATCH] unpaged: ZERO_PAGE in VM_UNPAGED

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It's strange enough to be looking out for anonymous pages in VM_UNPAGED areas,
let's not insert the ZERO_PAGE there - though whether it would matter will
depend on what we decide about ZERO_PAGE refcounting.

But whereas do_anonymous_page may (exceptionally) be called on a VM_UNPAGED
area, do_no_page should never be: just BUG_ON.

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 21:32:19 -08:00 committed by Linus Torvalds
parent ee498ed730
commit f57e88a8d8
2 changed files with 13 additions and 3 deletions
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2
drivers/char/mem.c
View File

@ -591,7 +591,7 @@ static inline size_t read_zero_pagealigned(char __user * buf, size_t size)
if (vma->vm_start > addr || (vma->vm_flags & VM_WRITE) == 0)
goto out_up;
if (vma->vm_flags & (VM_SHARED | VM_HUGETLB))
if (vma->vm_flags & (VM_SHARED | VM_HUGETLB | VM_UNPAGED))
break;
count = vma->vm_end - addr;
if (count > size)

14
mm/memory.c
View File

@ -1812,7 +1812,16 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
spinlock_t *ptl;
pte_t entry;
if (write_access) {
/*
* A VM_UNPAGED vma will normally be filled with present ptes
* by remap_pfn_range, and never arrive here; but it might have
* holes, or if !VM_DONTEXPAND, mremap might have expanded it.
* It's weird enough handling anon pages in unpaged vmas, we do
* not want to worry about ZERO_PAGEs too (it may or may not
* matter if their counts wrap): just give them anon pages.
*/
if (write_access || (vma->vm_flags & VM_UNPAGED)) {
/* Allocate our own private page. */
pte_unmap(page_table);
@ -1887,6 +1896,7 @@ static int do_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
int anon = 0;
pte_unmap(page_table);
BUG_ON(vma->vm_flags & VM_UNPAGED);
if (vma->vm_file) {
mapping = vma->vm_file->f_mapping;
@ -1962,7 +1972,7 @@ retry:
inc_mm_counter(mm, anon_rss);
lru_cache_add_active(new_page);
page_add_anon_rmap(new_page, vma, address);
} else if (!(vma->vm_flags & VM_UNPAGED)) {
} else {
inc_mm_counter(mm, file_rss);
page_add_file_rmap(new_page);
}