fs/proc/task_mmu: fix PAGE_IS_PFNZERO detection for the huge zero folio

is_zero_pfn() does not work for the huge zero folio. Fix it by using
is_huge_zero_pmd().

This can cause the PAGEMAP_SCAN ioctl against /proc/pid/pagemap to
present pages as PAGE_IS_PRESENT rather than as PAGE_IS_PFNZERO.

Found by code inspection.

Link: https://lkml.kernel.org/r/20250617143532.2375383-1-david@redhat.com
Fixes: 52526ca7fdb9 ("fs/proc/task_mmu: implement IOCTL to get and optionally clear info about PTEs")
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.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 27972c0749e7824076033d730e144bfa32995e3c..4be91eb6ea5cab43a4b9daae157f0e33545f65b2 100644 (file)
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -2182,7 +2182,7 @@ static unsigned long pagemap_thp_category(struct pagemap_scan_private *p,
                                categories |= PAGE_IS_FILE;
                }
 
-               if (is_zero_pfn(pmd_pfn(pmd)))
+               if (is_huge_zero_pmd(pmd))
                        categories |= PAGE_IS_PFNZERO;
                if (pmd_soft_dirty(pmd))
                        categories |= PAGE_IS_SOFT_DIRTY;