The patch titled
Subject: mm: userfaultfd: support UFFDIO_POISON for hugetlbfs
has been added to the -mm mm-unstable branch. Its filename is
mm-userfaultfd-support-uffdio_poison-for-hugetlbfs.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-userfaultfd-support-uffdio_poison-for-hugetlbfs.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
Subject: mm: userfaultfd: support UFFDIO_POISON for hugetlbfs
Date: Fri, 7 Jul 2023 14:55:37 -0700
The behavior here is the same as it is for anon/shmem. This is done
separately because hugetlb pte marker handling is a bit different.
Link: https://lkml.kernel.org/r/20230707215540.2324998-6-axelrasmussen@xxxxxxxxxx
Signed-off-by: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
Acked-by: Peter Xu <peterx@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Brian Geffon <bgeffon@xxxxxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Gaosheng Cui <cuigaosheng1@xxxxxxxxxx>
Cc: Huang, Ying <ying.huang@xxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: James Houghton <jthoughton@xxxxxxxxxx>
Cc: Jan Alexander Steffens (heftig) <heftig@xxxxxxxxxxxxx>
Cc: Jiaqi Yan <jiaqiyan@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Nadav Amit <namit@xxxxxxxxxx>
Cc: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Cc: Suleiman Souhlal <suleiman@xxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: T.J. Alumbaugh <talumbau@xxxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Cc: ZhangPeng <zhangpeng362@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 19 +++++++++++++++++++
mm/userfaultfd.c | 3 +--
2 files changed, 20 insertions(+), 2 deletions(-)
--- a/mm/hugetlb.c~mm-userfaultfd-support-uffdio_poison-for-hugetlbfs
+++ a/mm/hugetlb.c
@@ -6262,6 +6262,25 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_
int writable;
bool folio_in_pagecache = false;
+ if (uffd_flags_mode_is(flags, MFILL_ATOMIC_POISON)) {
+ ptl = huge_pte_lock(h, dst_mm, dst_pte);
+
+ /* Don't overwrite any existing PTEs (even markers) */
+ if (!huge_pte_none(huge_ptep_get(dst_pte))) {
+ spin_unlock(ptl);
+ return -EEXIST;
+ }
+
+ _dst_pte = make_pte_marker(PTE_MARKER_POISONED);
+ set_huge_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
+
+ /* No need to invalidate - it was non-present before */
+ update_mmu_cache(dst_vma, dst_addr, dst_pte);
+
+ spin_unlock(ptl);
+ return 0;
+ }
+
if (is_continue) {
ret = -EFAULT;
folio = filemap_lock_folio(mapping, idx);
--- a/mm/userfaultfd.c~mm-userfaultfd-support-uffdio_poison-for-hugetlbfs
+++ a/mm/userfaultfd.c
@@ -373,8 +373,7 @@ static __always_inline ssize_t mfill_ato
* by THP. Since we can not reliably insert a zero page, this
* feature is not supported.
*/
- if (uffd_flags_mode_is(flags, MFILL_ATOMIC_ZEROPAGE) ||
- uffd_flags_mode_is(flags, MFILL_ATOMIC_POISON)) {
+ if (uffd_flags_mode_is(flags, MFILL_ATOMIC_ZEROPAGE)) {
mmap_read_unlock(dst_mm);
return -EINVAL;
}
_
Patches currently in -mm which might be from axelrasmussen@xxxxxxxxxx are
mm-make-pte_marker_swapin_error-more-general.patch
mm-userfaultfd-check-for-start-len-overflow-in-validate_range.patch
mm-userfaultfd-extract-file-size-check-out-into-a-helper.patch
mm-userfaultfd-add-new-uffdio_poison-ioctl.patch
mm-userfaultfd-support-uffdio_poison-for-hugetlbfs.patch
mm-userfaultfd-document-and-enable-new-uffdio_poison-feature.patch
selftests-mm-refactor-uffd_poll_thread-to-allow-custom-fault-handlers.patch
selftests-mm-add-uffd-unit-test-for-uffdio_poison.patch
