linux-kernel - [PATCH v1] fs/proc/task_mmu: fix pagemap flags with PMD THP entries on 32bit

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Message-ID: <20241217195000.1734039-1-david@redhat.com>
Date: Tue, 17 Dec 2024 20:50:00 +0100
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org,
	David Hildenbrand <david@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Oscar Salvador <osalvador@...e.de>,
	stable@...r.kernel.org
Subject: [PATCH v1] fs/proc/task_mmu: fix pagemap flags with PMD THP entries on 32bit

Entries (including flags) are u64, even on 32bit. So right now we are
cutting of the flags on 32bit. This way, for example the cow selftest
complains about:

  # ./cow
  ...
  Bail Out! read and ioctl return unmatched results for populated: 0 1

Fixes: 2c1f057e5be6 ("fs/proc/task_mmu: properly detect PM_MMAP_EXCLUSIVE per page of PMD-mapped THPs")
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Oscar Salvador <osalvador@...e.de>
Cc: <stable@...r.kernel.org>
Signed-off-by: David Hildenbrand <david@...hat.com>
---
 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 38a5a3e9cba20..f02cd362309a0 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1810,7 +1810,7 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
 		}
 
 		for (; addr != end; addr += PAGE_SIZE, idx++) {
-			unsigned long cur_flags = flags;
+			u64 cur_flags = flags;
 			pagemap_entry_t pme;
 
 			if (folio && (flags & PM_PRESENT) &&
-- 
2.47.1