[30/36] Add VM_BUG_ONs to check for correct page order

clameter
2007-08-28T19:16:34Z

[-- Attachment #1: 0030-Add-VM_BUG_ONs-to-check-for-correct-page-order.patch --]
[-- Type: text/plain, Size: 3916 bytes --]

Before allowing different page orders it may be wise to get some checkpoints
in at various places. Checkpoints will help debugging whenever a wrong order
page shows up in a mapping. Helps when converting new filesystems to utilize
larger pages.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
---
fs/buffer.c | 1 +
mm/filemap.c | 18 +++++++++++++++---
2 files changed, 16 insertions(+), 3 deletions(-)

Index: linux-2.6/fs/buffer.c
===================================================================
--- linux-2.6.orig/fs/buffer.c 2007-08-27 20:52:34.000000000 -0700
+++ linux-2.6/fs/buffer.c 2007-08-27 21:09:19.000000000 -0700
@@ -893,6 +893,7 @@ struct buffer_head *alloc_page_buffers(s
long offset;
unsigned int page_size = page_cache_size(page->mapping);

+ BUG_ON(size > page_size);
try_again:
head = NULL;
offset = page_size;
Index: linux-2.6/mm/filemap.c
===================================================================
--- linux-2.6.orig/mm/filemap.c 2007-08-27 21:08:04.000000000 -0700
+++ linux-2.6/mm/filemap.c 2007-08-27 21:09:19.000000000 -0700
@@ -128,6 +128,7 @@ void remove_from_page_cache(struct page
struct address_space *mapping = page->mapping;

BUG_ON(!PageLocked(page));
+ VM_BUG_ON(mapping_order(mapping) != compound_order(page));

write_lock_irq(&mapping->tree_lock);
__remove_from_page_cache(page);
@@ -269,6 +270,7 @@ int wait_on_page_writeback_range(struct
if (page->index > end)
continue;

+ VM_BUG_ON(mapping_order(mapping) != compound_order(page));
wait_on_page_writeback(page);
if (PageError(page))
ret = -EIO;
@@ -440,6 +442,7 @@ int add_to_page_cache(struct page *page,
{
int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);

+ VM_BUG_ON(mapping_order(mapping) != compound_order(page));
if (error == 0) {
write_lock_irq(&mapping->tree_lock);
error = radix_tree_insert(&mapping->page_tree, offset, page);
@@ -599,8 +602,10 @@ struct page * find_get_page(struct addre

read_lock_irq(&mapping->tree_lock);
page = radix_tree_lookup(&mapping->page_tree, offset);
- if (page)
+ if (page) {
+ VM_BUG_ON(mapping_order(mapping) != compound_order(page));
page_cache_get(page);
+ }
read_unlock_irq(&mapping->tree_lock);
return page;
}
@@ -625,6 +630,7 @@ struct page *find_lock_page(struct addre
repeat:
page = radix_tree_lookup(&mapping->page_tree, offset);
if (page) {
+ VM_BUG_ON(mapping_order(mapping) != compound_order(page));
page_cache_get(page);
if (TestSetPageLocked(page)) {
read_unlock_irq(&mapping->tree_lock);
@@ -715,8 +721,10 @@ unsigned find_get_pages(struct address_s
read_lock_irq(&mapping->tree_lock);
ret = radix_tree_gang_lookup(&mapping->page_tree,
(void **)pages, start, nr_pages);
- for (i = 0; i < ret; i++)
+ for (i = 0; i < ret; i++) {
+ VM_BUG_ON(mapping_order(mapping) != compound_order(pages[i]));
page_cache_get(pages[i]);
+ }
read_unlock_irq(&mapping->tree_lock);
return ret;
}
@@ -746,6 +754,7 @@ unsigned find_get_pages_contig(struct ad
if (pages[i]->mapping == NULL || pages[i]->index != index)
break;

+ VM_BUG_ON(mapping_order(mapping) != compound_order(pages[i]));
page_cache_get(pages[i]);
index++;
}
@@ -774,8 +783,10 @@ unsigned find_get_pages_tag(struct addre
read_lock_irq(&mapping->tree_lock);
ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
(void **)pages, *index, nr_pages, tag);
- for (i = 0; i < ret; i++)
+ for (i = 0; i < ret; i++) {
+ VM_BUG_ON(mapping_order(mapping) != compound_order(pages[i]));
page_cache_get(pages[i]);
+ }
if (ret)
*index = pages[ret - 1]->index + 1;
read_unlock_irq(&mapping->tree_lock);
@@ -2233,6 +2244,7 @@ int try_to_release_page(struct page *pag
struct address_space * const mapping = page->mapping;

BUG_ON(!PageLocked(page));
+ VM_BUG_ON(mapping_order(mapping) != compound_order(page));
if (PageWriteback(page))
return 0;

--