On 7/16/19 5:07 AM, Vlastimil Babka wrote:
On 6/22/19 2:20 AM, Yang Shi wrote:
@@ -969,10 +975,21 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask,
/*
* page migration, thp tail pages can be passed.
*/
-static void migrate_page_add(struct page *page, struct list_head *pagelist,
+static int migrate_page_add(struct page *page, struct list_head *pagelist,
unsigned long flags)
{
struct page *head = compound_head(page);
+
+ /*
+ * Non-movable page may reach here. And, there may be
+ * temporaty off LRU pages or non-LRU movable pages.
+ * Treat them as unmovable pages since they can't be
+ * isolated, so they can't be moved at the moment. It
+ * should return -EIO for this case too.
+ */
+ if (!PageLRU(head) && (flags & MPOL_MF_STRICT))
+ return -EIO;
+
Hm but !PageLRU() is not the only way why queueing for migration can
fail, as can be seen from the rest of the function. Shouldn't all cases
be reported?
Do you mean the shared pages and isolation failed pages? I'm not sure
whether we should consider these cases break the semantics or not, so I
leave them as they are. But, strictly speaking they should be reported
too, at least for the isolation failed page.
Thanks,
Yang
/*
* Avoid migrating a page that is shared with others.
*/
@@ -984,6 +1001,8 @@ static void migrate_page_add(struct page *page, struct list_head *pagelist,
hpage_nr_pages(head));
}
}
+
+ return 0;
}
/* page allocation callback for NUMA node migration */
@@ -1186,9 +1205,10 @@ static struct page *new_page(struct page *page, unsigned long start)
}
#else
-static void migrate_page_add(struct page *page, struct list_head *pagelist,
+static int migrate_page_add(struct page *page, struct list_head *pagelist,
unsigned long flags)
{
+ return -EIO;
}
int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
