On 01.05.24 15:38, Zi Yan wrote:
On 1 May 2024, at 9:24, Alexander Gordeev wrote:
On Fri, Apr 26, 2024 at 03:02:53PM -0400, Zi Yan wrote:
Hi Zi,
It increasingly looks like this commit is crashing on s390 since
2024-04-30 in linux-next. If I do not miss something - since it
was included in mm-everything.
@@ -1553,9 +1558,10 @@ static __always_inline void __folio_remove_rmap(struct folio *folio,
* page of the folio is unmapped and at least one page
* is still mapped.
*/
- if (folio_test_large(folio) && folio_test_anon(folio))
- if (level == RMAP_LEVEL_PTE || nr < nr_pmdmapped)
- deferred_split_folio(folio);
+ if (folio_test_anon(folio) &&
+ list_empty(&folio->_deferred_list) &&
An attempt to reference folio->_deferred_list causes the crash below.
So if you remove this line, the crash no longer happens? It looks strange to
me that referencing a anonymous folio's _deferred_list would cause a crash.
Hmm, unless the folio is order-0.
Can you try the patch below and see if it fixes the crash? It moves partially_mapped
ahead to exclude order-0 folios.
diff --git a/mm/rmap.c b/mm/rmap.c
index 087a79f1f611..2d27c92bb6d5 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1557,9 +1557,8 @@ static __always_inline void __folio_remove_rmap(struct folio *folio,
* page of the folio is unmapped and at least one page
* is still mapped.
*/
- if (folio_test_anon(folio) &&
- list_empty(&folio->_deferred_list) &&
- partially_mapped)
+ if (folio_test_anon(folio) && partially_mapped &&
+ list_empty(&folio->_deferred_list))
deferred_split_folio(folio);
Yes, that should fix it and is the right thing to do. For small folios,
partially_mapped will always be false.
--
Cheers,
David / dhildenb
