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Revision e700898fa075c69b3ae02b702ab57fb75e1a82ec authored by Mike Kravetz on 12 December 2022, 23:50:41 UTC, committed by Andrew Morton on 21 December 2022, 22:31:52 UTC 
hugetlb: really allocate vma lock for all sharable vmas
 
Commit bbff39cc6cbc ("hugetlb: allocate vma lock for all sharable vmas")
removed the pmd sharable checks in the vma lock helper routines.  However,
it left the functional version of helper routines behind #ifdef
CONFIG_ARCH_WANT_HUGE_PMD_SHARE.  Therefore, the vma lock is not being
used for sharable vmas on architectures that do not support pmd sharing. 
On these architectures, a potential fault/truncation race is exposed that
could leave pages in a hugetlb file past i_size until the file is removed.

Move the functional vma lock helpers outside the ifdef, and remove the
non-functional stubs.  Since the vma lock is not just for pmd sharing,
rename the routine __vma_shareable_flags_pmd.

Link: https://lkml.kernel.org/r/20221212235042.178355-1-mike.kravetz@oracle.com
Fixes: bbff39cc6cbc ("hugetlb: allocate vma lock for all sharable vmas")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
1 parent 7ba594d
Raw File
pgalloc-track.h 
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_PGALLOC_TRACK_H
#define _LINUX_PGALLOC_TRACK_H

#if defined(CONFIG_MMU)
static inline p4d_t *p4d_alloc_track(struct mm_struct *mm, pgd_t *pgd,
				     unsigned long address,
				     pgtbl_mod_mask *mod_mask)
{
	if (unlikely(pgd_none(*pgd))) {
		if (__p4d_alloc(mm, pgd, address))
			return NULL;
		*mod_mask |= PGTBL_PGD_MODIFIED;
	}

	return p4d_offset(pgd, address);
}

static inline pud_t *pud_alloc_track(struct mm_struct *mm, p4d_t *p4d,
				     unsigned long address,
				     pgtbl_mod_mask *mod_mask)
{
	if (unlikely(p4d_none(*p4d))) {
		if (__pud_alloc(mm, p4d, address))
			return NULL;
		*mod_mask |= PGTBL_P4D_MODIFIED;
	}

	return pud_offset(p4d, address);
}

static inline pmd_t *pmd_alloc_track(struct mm_struct *mm, pud_t *pud,
				     unsigned long address,
				     pgtbl_mod_mask *mod_mask)
{
	if (unlikely(pud_none(*pud))) {
		if (__pmd_alloc(mm, pud, address))
			return NULL;
		*mod_mask |= PGTBL_PUD_MODIFIED;
	}

	return pmd_offset(pud, address);
}
#endif /* CONFIG_MMU */

#define pte_alloc_kernel_track(pmd, address, mask)			\
	((unlikely(pmd_none(*(pmd))) &&					\
	  (__pte_alloc_kernel(pmd) || ({*(mask)|=PGTBL_PMD_MODIFIED;0;})))?\
		NULL: pte_offset_kernel(pmd, address))

#endif /* _LINUX_PGALLOC_TRACK_H */
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