diff options
| author | Peter Xu <peterx@redhat.com> | 2023-01-04 17:52:07 -0500 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-01-18 17:12:53 -0800 |
| commit | d1751118c88673fe5a948ad82277898e9e284c55 (patch) | |
| tree | 9a7e10d925430d407a1ca1444b2b2ee15afc66ca /mm/hugetlb.c | |
| parent | a79390f5d6a78647fd70856bd42b22d994de0ba2 (diff) | |
mm/uffd: detect pgtable allocation failures
Before this patch, when there's any pgtable allocation issues happened
during change_protection(), the error will be ignored from the syscall.
For shmem, there will be an error dumped into the host dmesg. Two issues
with that:
(1) Doing a trace dump when allocation fails is not anything close to
grace.
(2) The user should be notified with any kind of such error, so the user
can trap it and decide what to do next, either by retrying, or stop
the process properly, or anything else.
For userfault users, this will change the API of UFFDIO_WRITEPROTECT when
pgtable allocation failure happened. It should not normally break anyone,
though. If it breaks, then in good ways.
One man-page update will be on the way to introduce the new -ENOMEM for
UFFDIO_WRITEPROTECT. Not marking stable so we keep the old behavior on
the 5.19-till-now kernels.
[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/20230104225207.1066932-4-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reported-by: James Houghton <jthoughton@google.com>
Acked-by: James Houghton <jthoughton@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/hugetlb.c')
| -rw-r--r-- | mm/hugetlb.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index a0d6d0980064..6fe65f14d33b 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6660,8 +6660,10 @@ long hugetlb_change_protection(struct vm_area_struct *vma, * pre-allocations to install pte markers. */ ptep = huge_pte_alloc(mm, vma, address, psize); - if (!ptep) + if (!ptep) { + pages = -ENOMEM; break; + } } ptl = huge_pte_lock(h, mm, ptep); if (huge_pmd_unshare(mm, vma, address, ptep)) { @@ -6751,7 +6753,7 @@ long hugetlb_change_protection(struct vm_area_struct *vma, hugetlb_vma_unlock_write(vma); mmu_notifier_invalidate_range_end(&range); - return pages << h->order; + return pages > 0 ? (pages << h->order) : pages; } /* Return true if reservation was successful, false otherwise. */ |