(Added lkml to CC:)
What happens:
When I do memory offline on ia64/NUMA box, __set_page_dirty_buffers() printed
out WARNINGS because the page under migration is not up-to-date.
Following is my investigation.
Assume 16k pages / 4 buffers of 4096bytes block (ext3).
4 buffers on a page of ext3.
At page offlining, we can find a page which is not up-to-date.
But all buffers of the page seems up-to-date.
buffers on a page by prink().
buffer 0, block_nr= some vaule, state= BH_uptodate | BH_Req| BH_Mapped
buffer 1, block_nr= -1, state= BH_uptodate
buffer 2, block_nr= -1, state= BH_uptodate
buffer 3, block_nr= -1, state= BH_uptodate
It seems no I/O for 3 buffers. It's because the page is the last page of inode
and blocks for buffer[1,2,3] is not assgined.
(maybe BH_uptodate is set by block_write_full_page().
Adding below check can hide the warning....but I can't say this is correct.
Can we set this page dirty silently in this case ?
===
+
+static int check_fragment_page(struct page *page, struct address_space *mapping
)
+{
+ struct inode *inode = mapping->host;
+ unsigned long lastblock, coverblock;
+
+ if (!page_has_buffers(page))
+ return 0;
+
+ lastblock = (i_size_read(inode) - 1) >> inode->i_blkbits;
+ coverblock = (page->index + 1) << (PAGE_SHIFT - inode->i_blkbits);
+
+ return coverblock > lastblock;
+}
+
+
+
static int __set_page_dirty(struct page *page,
struct address_space *mapping, int warn)
{
@@ -717,7 +734,9 @@ static int __set_page_dirty(struct page
write_lock_irq(&mapping->tree_lock);
if (page->mapping) { /* Race with truncate? */
- WARN_ON_ONCE(warn && !PageUptodate(page));
+ WARN_ON_ONCE(warn
+ && !PageUptodate(page)
+ && !check_fragment_page(page, mapping));
if (mapping_cap_account_dirty(mapping)) {
__inc_zone_page_state(page, NR_FILE_DIRTY);
==
Thanks,
-Kame
--
