On 6/19/22 11:49 AM, Matthew Wilcox wrote:
On Mon, Jun 13, 2022 at 08:48:40AM +0800, Xiubo Li wrote:
On 6/10/22 11:40 PM, Jeff Layton wrote:
Willy requested that we change this back to warning on folio->private
being non-NULl. He's trying to kill off the PG_private flag, and so we'd
like to catch where it's non-NULL.
Add a VM_WARN_ON_FOLIO (since it doesn't exist yet) and change over to
using that instead of VM_BUG_ON_FOLIO along with testing the ->private
pointer.
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/ceph/addr.c | 2 +-
include/linux/mmdebug.h | 9 +++++++++
2 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index b43cc01a61db..b24d6bdb91db 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -122,7 +122,7 @@ static bool ceph_dirty_folio(struct address_space *mapping, struct folio *folio)
* Reference snap context in folio->private. Also set
* PagePrivate so that we get invalidate_folio callback.
*/
- VM_BUG_ON_FOLIO(folio_test_private(folio), folio);
+ VM_WARN_ON_FOLIO(folio->private, folio);
folio_attach_private(folio, snapc);
return ceph_fscache_dirty_folio(mapping, folio);
I found a couple of places where page->private needs to be NULLed out.
Neither of them are Ceph's fault. I decided that testing whether
folio->private and PG_private are in agreement was better done in
folio_unlock() than in any of the other potential places we could
check for it.
Hi Willy,
Cool. I will test this patch today. Thanks!
-- Xiubo
diff --git a/mm/filemap.c b/mm/filemap.c
index 8ef861297ffb..acef71f75e78 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1535,6 +1535,9 @@ void folio_unlock(struct folio *folio)
BUILD_BUG_ON(PG_waiters != 7);
BUILD_BUG_ON(PG_locked > 7);
VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
+ VM_BUG_ON_FOLIO(!folio_test_private(folio) &&
+ !folio_test_swapbacked(folio) &&
+ folio_get_private(folio), folio);
if (clear_bit_unlock_is_negative_byte(PG_locked, folio_flags(folio, 0)))
folio_wake_bit(folio, PG_locked);
}
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2e2a8b5bc567..af0751a79c19 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2438,6 +2438,7 @@ 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 eb62e026c501..fa8e36e74f0d 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1157,6 +1157,8 @@ static int unmap_and_move(new_page_t get_new_page,
newpage = get_new_page(page, private);
if (!newpage)
return -ENOMEM;
+ BUG_ON(compound_order(newpage) != compound_order(page));
+ newpage->private = 0;
rc = __unmap_and_move(page, newpage, force, mode);
if (rc == MIGRATEPAGE_SUCCESS)
