Hi,
Christoph Lameter wrote:
+int migrate_page_remove_references(struct page *newpage, struct page *page, int nr_refs)
+{
+ write_lock_irq(&mapping->tree_lock);
+
+ radix_pointer = (struct page **)radix_tree_lookup_slot(
+ &mapping->page_tree,
+ page_index(page));
+
+ if (!page->mapping ||
+ page_count(page) != nr_refs ||
+ *radix_pointer != page) {
+ write_unlock_irq(&mapping->tree_lock);
+ return 1;
+ }
I'm testing memory hot removing patch based on your patch.
I found a problem around the shmem,
but I'm not sure whether it can be problem on migration or not.
Problem is:
1. a page of shmem(tmpfs)'s generic file is in page-cache. assume page is diry.
2. When it passed to migrate_page(), it reaches pageout() in the middle of migrate_page().
3. pageout calls shmem_writepage(), and the page turns to be swap-cache page.
At this point, page->mapping becomes NULL (see move_to_swapcache())
4. pageout retunrs PAGE_SUCCESS.
5. Finaly, migrate_page() goes to redo.
6. retry
7. Because spwapper_space's a_ops->migratepage is not NULL,
"Avoid write back hook" in patch 7/7 is used.
+ if (mapping->a_ops->migratepage) {
+ rc = mapping->a_ops->migratepage(newpage, page);
+ goto unlock_both;
+ }
a_ops->migrate_page points to migrate_page() in mm/vmscan.c
8. migrate_page() try to replace radix tree entry in swapper_space.
9. Becasue page->mapping is NULL(becasue of 3), migrate_page_remove_references() fails.
I avoid above situation by following code in migrate_page_remove_references() now.
But I'm not sure whether this is sane fix or not.
> + if ((!PageSwapCache(page) && !page->mapping) ||
> + page_count(page) != nr_refs ||
> + *radix_pointer != page) {
> + write_unlock_irq(&mapping->tree_lock);
> + return 1;
> + }
-- Kame
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
