[PATCH 2/6] fs/proc/task_mmu: use huge_page_size() in pagemap_scan_hugetlb_entry()

[Kiryl Shutsemau (Meta)]

The partial-page check compares against HPAGE_SIZE (PMD_SIZE), which
is wrong for gigantic hugetlb hstates (e.g. 1G). The walker hands the
callback a huge_page_size()-sized range, never start + HPAGE_SIZE, so
the comparison always declares it partial and aborts the WP. Compare
against the actual hstate's page size.

Fixes: 52526ca7fdb9 ("fs/proc/task_mmu: implement IOCTL to get and optionally clear info about PTEs")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Sashiko AI review <sashiko-bot@xxxxxxxxxx>
Signed-off-by: Kiryl Shutsemau <kas@xxxxxxxxxx>
---
 fs/proc/task_mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index e21a38ac745b..1489c67e88f7 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -2960,7 +2960,7 @@ static int pagemap_scan_hugetlb_entry(pte_t *ptep, unsigned long hmask,
 	if (~categories & PAGE_IS_WRITTEN)
 		goto out_unlock;
 
-	if (end != start + HPAGE_SIZE) {
+	if (end != start + huge_page_size(hstate_vma(vma))) {
 		/* Partial HugeTLB page WP isn't possible. */
 		pagemap_scan_backout_range(p, start, end);
 		p->arg.walk_end = start;
-- 
2.54.0