diff options
| author | Kiryl Shutsemau (Meta) <kas@kernel.org> | 2026-05-29 20:23:28 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-06-09 04:21:29 +0300 |
| commit | f7e2c21bd1f57cd5350eecdfdb5d6025ca6afbab (patch) | |
| tree | 900856bd4ded997e59bd7e296999d638f1ced308 | |
| parent | e92d92bbafb264dc0518d52b846a3c07ed8d523f (diff) | |
| download | linux-f7e2c21bd1f57cd5350eecdfdb5d6025ca6afbab.tar.xz | |
mm/huge_memory: preserve pmd_swp_uffd_wp on device-private PMD downgrade
change_non_present_huge_pmd() rewrites a writable device-private PMD swap
entry into a readable one without carrying pmd_swp_uffd_wp() across. The
PTE-level change_softleaf_pte() does this correctly; mirror that here,
matching what copy_huge_pmd() does for the fork path. Without the carry,
a plain mprotect() over a UFFD_WP-marked device-private THP strips the bit
and the trap is bypassed on swap-in.
Link: https://lore.kernel.org/20260529172331.356655-5-kas@kernel.org
Fixes: 368076f52ebe ("mm/huge_memory: add device-private THP support to PMD operations")
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Reported-by: Sashiko AI review <sashiko-bot@kernel.org>
Reviewed-by: Balbir Singh <balbirs@nvidia.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Lorenzo Stoakes <ljs@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: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | mm/huge_memory.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index da851a5696d5..a5176653ba1f 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2565,6 +2565,8 @@ static void change_non_present_huge_pmd(struct mm_struct *mm, } else if (softleaf_is_device_private_write(entry)) { entry = make_readable_device_private_entry(swp_offset(entry)); newpmd = swp_entry_to_pmd(entry); + if (pmd_swp_uffd_wp(*pmd)) + newpmd = pmd_swp_mkuffd_wp(newpmd); } else { newpmd = *pmd; } |