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authorNick Piggin <nickpiggin@yahoo.com.au>2005-10-29 18:16:12 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-10-29 21:40:39 -0700
commitb5810039a54e5babf428e9a1e89fc1940fabff11 (patch)
tree835836cb527ec9bd525f93eb7e016f3dfb8c8ae2 /mm/filemap_xip.c
parentf9c98d0287de42221c624482fd4f8d485c98ab22 (diff)
downloadlinux-b5810039a54e5babf428e9a1e89fc1940fabff11.tar.gz
[PATCH] core remove PageReserved
Remove PageReserved() calls from core code by tightening VM_RESERVED handling in mm/ to cover PageReserved functionality. PageReserved special casing is removed from get_page and put_page. All setting and clearing of PageReserved is retained, and it is now flagged in the page_alloc checks to help ensure we don't introduce any refcount based freeing of Reserved pages. MAP_PRIVATE, PROT_WRITE of VM_RESERVED regions is tentatively being deprecated. We never completely handled it correctly anyway, and is be reintroduced in future if required (Hugh has a proof of concept). Once PageReserved() calls are removed from kernel/power/swsusp.c, and all arch/ and driver code, the Set and Clear calls, and the PG_reserved bit can be trivially removed. Last real user of PageReserved is swsusp, which uses PageReserved to determine whether a struct page points to valid memory or not. This still needs to be addressed (a generic page_is_ram() should work). A last caveat: the ZERO_PAGE is now refcounted and managed with rmap (and thus mapcounted and count towards shared rss). These writes to the struct page could cause excessive cacheline bouncing on big systems. There are a number of ways this could be addressed if it is an issue. Signed-off-by: Nick Piggin <npiggin@suse.de> Refcount bug fix for filemap_xip.c Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/filemap_xip.c')
-rw-r--r--mm/filemap_xip.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c
index 8c199f53773..9354ee279b1 100644
--- a/mm/filemap_xip.c
+++ b/mm/filemap_xip.c
@@ -174,6 +174,7 @@ __xip_unmap (struct address_space * mapping,
unsigned long address;
pte_t *pte;
pte_t pteval;
+ struct page *page = ZERO_PAGE(address);
spin_lock(&mapping->i_mmap_lock);
vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
@@ -185,15 +186,17 @@ __xip_unmap (struct address_space * mapping,
* We need the page_table_lock to protect us from page faults,
* munmap, fork, etc...
*/
- pte = page_check_address(ZERO_PAGE(address), mm,
- address);
+ pte = page_check_address(page, mm, address);
if (!IS_ERR(pte)) {
/* Nuke the page table entry. */
flush_cache_page(vma, address, pte_pfn(*pte));
pteval = ptep_clear_flush(vma, address, pte);
+ page_remove_rmap(page);
+ dec_mm_counter(mm, file_rss);
BUG_ON(pte_dirty(pteval));
pte_unmap(pte);
spin_unlock(&mm->page_table_lock);
+ page_cache_release(page);
}
}
spin_unlock(&mapping->i_mmap_lock);
@@ -228,7 +231,7 @@ xip_file_nopage(struct vm_area_struct * area,
page = mapping->a_ops->get_xip_page(mapping, pgoff*(PAGE_SIZE/512), 0);
if (!IS_ERR(page)) {
- return page;
+ goto out;
}
if (PTR_ERR(page) != -ENODATA)
return NULL;
@@ -249,6 +252,8 @@ xip_file_nopage(struct vm_area_struct * area,
page = ZERO_PAGE(address);
}
+out:
+ page_cache_get(page);
return page;
}