From: Kiryl Shutsemau (Meta) <kas@kernel.org>
Date: Fri, 29 May 2026 17:23:26 +0000 (+0100)
Subject: fs/proc/task_mmu: use huge_page_size() in pagemap_scan_hugetlb_entry()
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=1b074e3270e1c061c829150c742eb83bad4dddd1;p=thirdparty%2Fkernel%2Flinux.git

fs/proc/task_mmu: use huge_page_size() in pagemap_scan_hugetlb_entry()

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.

Link: https://lore.kernel.org/20260529172331.356655-3-kas@kernel.org
Fixes: 52526ca7fdb9 ("fs/proc/task_mmu: implement IOCTL to get and optionally clear info about PTEs")
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Reported-by: Sashiko AI review <sashiko-bot@kernel.org>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

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;