6.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Andrew Bresticker <abrestic@xxxxxxxxxxxx>
commit ab1ffc86cb5bec1c92387b9811d9036512f8f4eb upstream.
The requirement that the head page be passed to do_set_pmd() was added in
commit ef37b2ea08ac ("mm/memory: page_add_file_rmap() ->
folio_add_file_rmap_[pte|pmd]()") and prevents pmd-mapping in the
finish_fault() and filemap_map_pages() paths if the page to be inserted is
anything but the head page for an otherwise suitable vma and pmd-sized
page.
Matthew said:
: We're going to stop using PMDs to map large folios unless the fault is
: within the first 4KiB of the PMD. No idea how many workloads that
: affects, but it only needs to be backported as far as v6.8, so we may
: as well backport it.
Link: https://lkml.kernel.org/r/20240611153216.2794513-1-abrestic@xxxxxxxxxxxx
Fixes: ef37b2ea08ac ("mm/memory: page_add_file_rmap() -> folio_add_file_rmap_[pte|pmd]()")
Signed-off-by: Andrew Bresticker <abrestic@xxxxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Acked-by: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4583,8 +4583,9 @@ vm_fault_t do_set_pmd(struct vm_fault *v
if (!thp_vma_suitable_order(vma, haddr, PMD_ORDER))
return ret;
- if (page != &folio->page || folio_order(folio) != HPAGE_PMD_ORDER)
+ if (folio_order(folio) != HPAGE_PMD_ORDER)
return ret;
+ page = &folio->page;
/*
* Just backoff if any subpage of a THP is corrupted otherwise
