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| author |   Hugh Dickins <hughd@google.com> | 2023-04-18 22:22:02 -0700 |
|---|---|---|
| committer |   Andrew Morton <akpm@linux-foundation.org> | 2023-04-21 14:52:04 -0700 |
| commit | f724392415b3e1ae844d2766669c0d955fe9a17b (patch) | |
| tree | 7ce7fd319cf2f3ebd1c2f84464613c0b960feae2 | |
| parent | maple_tree: fix allocation in mas_sparse_area() (diff) | |
| download | wireguard-linux-f724392415b3e1ae844d2766669c0d955fe9a17b.tar.xz wireguard-linux-f724392415b3e1ae844d2766669c0d955fe9a17b.zip | |
hugetlb: pte_alloc_huge() to replace huge pte_alloc_map()
Some architectures can have their hugetlb pages down at the lowest PTE
level: their huge_pte_alloc() using pte_alloc_map(), but without any
following pte_unmap(). Since none of these arches uses CONFIG_HIGHPTE,
this is not seen as a problem at present; but would become a problem if
forthcoming changes were to add an rcu_read_lock() into pte_offset_map(),
with the rcu_read_unlock() expected in pte_unmap().
Similarly in their huge_pte_offset(): pte_offset_kernel() is good enough
for that, but it's probably less confusing if we define pte_offset_huge()
along with pte_alloc_huge(). Only define them without CONFIG_HIGHPTE: so
there would be a build error to signal if ever more work is needed.
For ease of development, define these now for 6.4-rc1, ahead of any use:
then architectures can integrate patches using them, independent from mm.
Link: https://lkml.kernel.org/r/ae9e7d98-8a3a-cfd9-4762-bcddffdf96cf@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | include/linux/hugetlb.h | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 28703fe22386..cbe1e97a15a1 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -191,6 +191,23 @@ extern struct list_head huge_boot_pages; /* arch callbacks */ +#ifndef CONFIG_HIGHPTE +/* + * pte_offset_huge() and pte_alloc_huge() are helpers for those architectures + * which may go down to the lowest PTE level in their huge_pte_offset() and + * huge_pte_alloc(): to avoid reliance on pte_offset_map() without pte_unmap(). + */ +static inline pte_t *pte_offset_huge(pmd_t *pmd, unsigned long address) +{ + return pte_offset_kernel(pmd, address); +} +static inline pte_t *pte_alloc_huge(struct mm_struct *mm, pmd_t *pmd, + unsigned long address) +{ + return pte_alloc(mm, pmd) ? NULL : pte_offset_huge(pmd, address); +} +#endif + pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, unsigned long sz); /* |