diff options
| author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2022-06-19 10:37:32 -0400 |
|---|---|---|
| committer | Matthew Wilcox (Oracle) <willy@infradead.org> | 2022-06-23 12:21:44 -0400 |
| commit | b653db77350c7307a513b81856fe53e94cf42446 (patch) | |
| tree | cb4f733ccff7026b5cd4eaa3220e282bcd90a07a | |
| parent | cb995f4eeba9d268fd4b56c2423ad6c1d1ea1b82 (diff) | |
mm: Clear page->private when splitting or migrating a page
In our efforts to remove uses of PG_private, we have found folios with
the private flag clear and folio->private not-NULL. That is the root
cause behind 642d51fb0775 ("ceph: check folio PG_private bit instead
of folio->private"). It can also affect a few other filesystems that
haven't yet reported a problem.
compaction_alloc() can return a page with uninitialised page->private,
and rather than checking all the callers of migrate_pages(), just zero
page->private after calling get_new_page(). Similarly, the tail pages
from split_huge_page() may also have an uninitialised page->private.
Reported-by: Xiubo Li <xiubli@redhat.com>
Tested-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
| -rw-r--r-- | mm/huge_memory.c | 1 | ||||
| -rw-r--r-- | mm/migrate.c | 1 |
2 files changed, 2 insertions, 0 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index f7248002dad9..834f288b3769 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2377,6 +2377,7 @@ static void __split_huge_page_tail(struct page *head, int tail, page_tail); page_tail->mapping = head->mapping; page_tail->index = head->index + tail; + page_tail->private = 0; /* Page flags must be visible before we make the page non-compound. */ smp_wmb(); diff --git a/mm/migrate.c b/mm/migrate.c index e51588e95f57..6c1ea61f39d8 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1106,6 +1106,7 @@ static int unmap_and_move(new_page_t get_new_page, if (!newpage) return -ENOMEM; + newpage->private = 0; rc = __unmap_and_move(page, newpage, force, mode); if (rc == MIGRATEPAGE_SUCCESS) set_page_owner_migrate_reason(newpage, reason); |