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mm/gup: Fix some contiguous memmap assumptions 

Several functions in gup.c assume that a compound page has virtually
contiguous page structs.  This isn't true for SPARSEMEM configs unless
SPARSEMEM_VMEMMAP is also set.  Fix them by using nth_page() instead of
plain pointer arithmetic.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
This commit is contained in:
Matthew Wilcox (Oracle) 2022-01-07 13:25:55 -05:00
parent 28297dbcad
commit c228afb11a
1 changed files with 7 additions and 7 deletions
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14
mm/gup.c
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@ -258,7 +258,7 @@ static inline struct page *compound_range_next(struct page *start,
struct page *next, *page;
unsigned int nr = 1;
next = start + i;
next = nth_page(start, i);
page = compound_head(next);
if (PageHead(page))
nr = min_t(unsigned int,
@ -2440,8 +2440,8 @@ static int record_subpages(struct page *page, unsigned long addr,
{
int nr;
for (nr = 0; addr != end; addr += PAGE_SIZE)
pages[nr++] = page++;
for (nr = 0; addr != end; nr++, addr += PAGE_SIZE)
pages[nr] = nth_page(page, nr);
return nr;
}
@ -2476,7 +2476,7 @@ static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
head = pte_page(pte);
page = head + ((addr & (sz-1)) >> PAGE_SHIFT);
page = nth_page(head, (addr & (sz - 1)) >> PAGE_SHIFT);
refs = record_subpages(page, addr, end, pages + *nr);
head = try_grab_compound_head(head, refs, flags);
@ -2536,7 +2536,7 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
pages, nr);
}
page = pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
page = nth_page(pmd_page(orig), (addr & ~PMD_MASK) >> PAGE_SHIFT);
refs = record_subpages(page, addr, end, pages + *nr);
head = try_grab_compound_head(pmd_page(orig), refs, flags);
@ -2570,7 +2570,7 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
pages, nr);
}
page = pud_page(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
page = nth_page(pud_page(orig), (addr & ~PUD_MASK) >> PAGE_SHIFT);
refs = record_subpages(page, addr, end, pages + *nr);
head = try_grab_compound_head(pud_page(orig), refs, flags);
@ -2599,7 +2599,7 @@ static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr,
BUILD_BUG_ON(pgd_devmap(orig));
page = pgd_page(orig) + ((addr & ~PGDIR_MASK) >> PAGE_SHIFT);
page = nth_page(pgd_page(orig), (addr & ~PGDIR_MASK) >> PAGE_SHIFT);
refs = record_subpages(page, addr, end, pages + *nr);
head = try_grab_compound_head(pgd_page(orig), refs, flags);