iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

hugetlb: pte_alloc_huge() to replace huge pte_alloc_map()

Browse Source 
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>
This commit is contained in:
Hugh Dickins 2023-04-18 22:22:02 -07:00 committed by Andrew Morton
parent 29ad6bb313
commit f724392415
1 changed files with 17 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
include/linux/hugetlb.h
View File

@ -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);
/*