hollalinux
/
linux-sg2042
mirror of https://github.com/sophgo/linux-riscv.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

mm/hugetlb: pre-allocate pgtable pages for uffd wr-protects 

commit fed15f1345 upstream.

Userfaultfd-wp uses pte markers to mark wr-protected pages for both shmem
and hugetlb.  Shmem has pre-allocation ready for markers, but hugetlb path
was overlooked.

Doing so by calling huge_pte_alloc() if the initial pgtable walk fails to
find the huge ptep.  It's possible that huge_pte_alloc() can fail with
high memory pressure, in that case stop the loop immediately and fail
silently.  This is not the most ideal solution but it matches with what we
do with shmem meanwhile it avoids the splat in dmesg.

Link: https://lkml.kernel.org/r/20230104225207.1066932-2-peterx@redhat.com
Fixes: 60dfaad65a ("mm/hugetlb: allow uffd wr-protect none ptes")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reported-by: James Houghton <jthoughton@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: James Houghton <jthoughton@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: <stable@vger.kernel.org>	[5.19+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Xu 2023-01-04 17:52:05 -05:00 committed by Greg Kroah-Hartman
parent 8d6a675cd7
commit 3b8ede6665
1 changed files with 11 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
mm/hugetlb.c
View File

@ -6604,8 +6604,17 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
spinlock_t *ptl;
ptep = huge_pte_offset(mm, address, psize);
if (!ptep) {
address |= last_addr_mask;
continue;
if (!uffd_wp) {
address |= last_addr_mask;
continue;
}
/*
* Userfaultfd wr-protect requires pgtable
* pre-allocations to install pte markers.
*/
ptep = huge_pte_alloc(mm, vma, address, psize);
if (!ptep)
break;
}
ptl = huge_pte_lock(h, mm, ptep);
if (huge_pmd_unshare(mm, vma, address, ptep)) {