[PATCH v1 07/11] mm/huge_memory: convert split_huge_pages_pid() from follow_page() to folio_walk

David Hildenbrand
2024-08-02T15:56:25Z

Let's remove yet another follow_page() user. Note that we have to do the
split without holding the PTL, after folio_walk_end(). We don't care
about losing the secretmem check in follow_page().

Signed-off-by: David Hildenbrand <david@redhat.com>
---
mm/huge_memory.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 0167dc27e365..697fcf89f975 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -40,6 +40,7 @@
#include <linux/memory-tiers.h>
#include <linux/compat.h>
#include <linux/pgalloc_tag.h>
+#include <linux/pagewalk.h>

#include <asm/tlb.h>
#include <asm/pgalloc.h>
@@ -3507,7 +3508,7 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
*/
for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) {
struct vm_area_struct *vma = vma_lookup(mm, addr);
- struct page *page;
+ struct folio_walk fw;
struct folio *folio;

if (!vma)
@@ -3519,13 +3520,10 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
continue;
}

- /* FOLL_DUMP to ignore special (like zero) pages */
- page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
-
- if (IS_ERR_OR_NULL(page))
+ folio = folio_walk_start(&fw, vma, addr, 0);
+ if (!folio)
continue;

- folio = page_folio(page);
if (!is_transparent_hugepage(folio))
goto next;

@@ -3544,13 +3542,19 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start,

if (!folio_trylock(folio))
goto next;
+ folio_get(folio);
+ folio_walk_end(&fw, vma);

if (!split_folio_to_order(folio, new_order))
split++;

folio_unlock(folio);
-next:
folio_put(folio);
+
+ cond_resched();
+ continue;
+next:
+ folio_walk_end(&fw, vma);
cond_resched();
}
mmap_read_unlock(mm);
--
2.45.2