+ userfaultfd-add-minor-fault-registration-mode-fix.patch added to -mm tree

+ userfaultfd-add-minor-fault-registration-mode-fix.patch added to -mm tree

[akpm]

The patch titled
     Subject: userfaultfd/hugetlbfs: fix minor fault page leak
has been added to the -mm tree.  Its filename is
     userfaultfd-add-minor-fault-registration-mode-fix.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/userfaultfd-add-minor-fault-registration-mode-fix.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/userfaultfd-add-minor-fault-registration-mode-fix.patch

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The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: Peter Xu <peterx@redhat.com>
Subject: userfaultfd/hugetlbfs: fix minor fault page leak

When uffd-minor enabled, we need to put the page cache before handling the
userfault in hugetlb_no_page(), otherwise the page refcount got leaked.

This can be reproduced by running userfaultfd selftest with hugetlb_shared
mode, then cat /proc/meminfo.

Link: https://lkml.kernel.org/r/20210322175132.36659-1-peterx@redhat.com
Fixes: f2bf15fb0969 ("userfaultfd: add minor fault registration mode")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/hugetlb.c |    1 +
 1 file changed, 1 insertion(+)

--- a/mm/hugetlb.c~userfaultfd-add-minor-fault-registration-mode-fix
+++ a/mm/hugetlb.c
@@ -4565,6 +4565,7 @@ retry:
 		/* Check for page in userfault range. */
 		if (userfaultfd_minor(vma)) {
 			unlock_page(page);
+			put_page(page);
 			ret = hugetlb_handle_userfault(vma, mapping, idx,
 						       flags, haddr,
 						       VM_UFFD_MINOR);
_

Patches currently in -mm which might be from peterx@redhat.com are

hugetlb-pass-vma-into-huge_pte_alloc-and-huge_pmd_share.patch
hugetlb-pass-vma-into-huge_pte_alloc-and-huge_pmd_share-fix.patch
hugetlb-userfaultfd-forbid-huge-pmd-sharing-when-uffd-enabled.patch
hugetlb-userfaultfd-forbid-huge-pmd-sharing-when-uffd-enabled-fix.patch
mm-hugetlb-move-flush_hugetlb_tlb_range-into-hugetlbh.patch
hugetlb-userfaultfd-unshare-all-pmds-for-hugetlbfs-when-register-wp.patch
userfaultfd-add-minor-fault-registration-mode-fix.patch
userfaultfd-selftests-use-user-mode-only.patch
userfaultfd-selftests-remove-the-time-check-on-delayed-uffd.patch
userfaultfd-selftests-dropping-verify-check-in-locking_thread.patch
userfaultfd-selftests-only-dump-counts-if-mode-enabled.patch
userfaultfd-selftests-unify-error-handling.patch