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mm/gup: remove record_subpages()

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We can just cleanup the code by calculating the #refs earlier, so we can
just inline what remains of record_subpages().

Calculate the number of references/pages ahead of times, and record them
only once all our tests passed.

[david@redhat.com: fix `pages' adjustment]
  Link: https://lkml.kernel.org/r/cc7f03f8-da8b-407e-a03a-e8e5a9ec5462@redhat.com
Link: https://lkml.kernel.org/r/20250901150359.867252-20-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Hildenbrand 2025-09-01 17:03:40 +02:00 • committed by Andrew Morton
parent 541541dbfe
commit e3c05b6e37
1 changed files with 10 additions and 17 deletions
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27
mm/gup.c
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@ -484,19 +484,6 @@ static inline void mm_set_has_pinned_flag(struct mm_struct *mm)
#ifdef CONFIG_MMU
#ifdef CONFIG_HAVE_GUP_FAST
static int record_subpages(struct page *page, unsigned long sz,
unsigned long addr, unsigned long end,
struct page **pages)
{
int nr;
page += (addr & (sz - 1)) >> PAGE_SHIFT;
for (nr = 0; addr != end; nr++, addr += PAGE_SIZE)
pages[nr] = page++;
return nr;
}
/**
* try_grab_folio_fast() - Attempt to get or pin a folio in fast path.
* @page: pointer to page to be grabbed
@ -2971,8 +2958,8 @@ static int gup_fast_pmd_leaf(pmd_t orig, pmd_t *pmdp, unsigned long addr,
if (pmd_special(orig))
return 0;
page = pmd_page(orig);
refs = record_subpages(page, PMD_SIZE, addr, end, pages + *nr);
refs = (end - addr) >> PAGE_SHIFT;
page = pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
folio = try_grab_folio_fast(page, refs, flags);
if (!folio)
@ -2992,7 +2979,10 @@ static int gup_fast_pmd_leaf(pmd_t orig, pmd_t *pmdp, unsigned long addr,
return 0;
}
pages += *nr;
*nr += refs;
for (; refs; refs--)
*(pages++) = page++;
folio_set_referenced(folio);
return 1;
}
@ -3011,8 +3001,8 @@ static int gup_fast_pud_leaf(pud_t orig, pud_t *pudp, unsigned long addr,
if (pud_special(orig))
return 0;
page = pud_page(orig);
refs = record_subpages(page, PUD_SIZE, addr, end, pages + *nr);
refs = (end - addr) >> PAGE_SHIFT;
page = pud_page(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
folio = try_grab_folio_fast(page, refs, flags);
if (!folio)
@ -3033,7 +3023,10 @@ static int gup_fast_pud_leaf(pud_t orig, pud_t *pudp, unsigned long addr,
return 0;
}
pages += *nr;
*nr += refs;
for (; refs; refs--)
*(pages++) = page++;
folio_set_referenced(folio);
return 1;
}