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authorHugh Dickins <hughd@google.com>2023-06-08 18:26:04 -0700
committerAndrew Morton <akpm@linux-foundation.org>2023-06-19 16:19:15 -0700
commit3622d3cde30898c1b6eafde281c122b994718c58 (patch)
tree7568d3b856fc1c6e9947868953a5f7b826b41daf /mm
parent2b683a4ff6ee091d5764ad867fbfae65f80cfefb (diff)
downloadlwn-3622d3cde30898c1b6eafde281c122b994718c58.tar.gz
lwn-3622d3cde30898c1b6eafde281c122b994718c58.zip
mm/userfaultfd: allow pte_offset_map_lock() to fail
mfill_atomic_install_pte() and mfill_atomic_pte_zeropage() treat failed pte_offset_map_lock() as -EAGAIN, which mfill_atomic() already returns to user for a similar race. Link: https://lkml.kernel.org/r/50cf3930-1bfa-4de9-a079-3da47b7ce17b@google.com Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Christoph Hellwig <hch@infradead.org> Cc: David Hildenbrand <david@redhat.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: SeongJae Park <sj@kernel.org> Cc: Song Liu <song@kernel.org> Cc: Steven Price <steven.price@arm.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com> Cc: Will Deacon <will@kernel.org> Cc: Yang Shi <shy828301@gmail.com> Cc: Yu Zhao <yuzhao@google.com> Cc: Zack Rusin <zackr@vmware.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/userfaultfd.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index e97a0b4889fc..5fd787158c70 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -76,7 +76,10 @@ int mfill_atomic_install_pte(pmd_t *dst_pmd,
if (flags & MFILL_ATOMIC_WP)
_dst_pte = pte_mkuffd_wp(_dst_pte);
+ ret = -EAGAIN;
dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
+ if (!dst_pte)
+ goto out;
if (vma_is_shmem(dst_vma)) {
/* serialize against truncate with the page table lock */
@@ -121,6 +124,7 @@ int mfill_atomic_install_pte(pmd_t *dst_pmd,
ret = 0;
out_unlock:
pte_unmap_unlock(dst_pte, ptl);
+out:
return ret;
}
@@ -212,7 +216,10 @@ static int mfill_atomic_pte_zeropage(pmd_t *dst_pmd,
_dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr),
dst_vma->vm_page_prot));
+ ret = -EAGAIN;
dst_pte = pte_offset_map_lock(dst_vma->vm_mm, dst_pmd, dst_addr, &ptl);
+ if (!dst_pte)
+ goto out;
if (dst_vma->vm_file) {
/* the shmem MAP_PRIVATE case requires checking the i_size */
inode = dst_vma->vm_file->f_inode;
@@ -231,6 +238,7 @@ static int mfill_atomic_pte_zeropage(pmd_t *dst_pmd,
ret = 0;
out_unlock:
pte_unmap_unlock(dst_pte, ptl);
+out:
return ret;
}