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mm/gup: Remove hpage_pincount_add()

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It's clearer to call atomic_add() in the callers; the assertions clearly
can't fire there because they're part of the condition for calling
atomic_add().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Matthew Wilcox (Oracle) 2022-01-07 14:15:11 -05:00
parent 59409373f6
commit 78d9d6ced3
1 changed files with 11 additions and 20 deletions
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31
mm/gup.c
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@ -29,14 +29,6 @@ struct follow_page_context {
unsigned int page_mask;
};
static void hpage_pincount_add(struct page *page, int refs)
{
VM_BUG_ON_PAGE(!hpage_pincount_available(page), page);
VM_BUG_ON_PAGE(page != compound_head(page), page);
atomic_add(refs, compound_pincount_ptr(page));
}
static void hpage_pincount_sub(struct page *page, int refs)
{
VM_BUG_ON_PAGE(!hpage_pincount_available(page), page);
@ -151,17 +143,17 @@ __maybe_unused struct page *try_grab_compound_head(struct page *page,
return NULL;
/*
* When pinning a compound page of order > 1 (which is what
* hpage_pincount_available() checks for), use an exact count to
* track it, via hpage_pincount_add/_sub().
* When pinning a compound page of order > 1 (which is
* what hpage_pincount_available() checks for), use an
* exact count to track it.
*
* However, be sure to *also* increment the normal page refcount
* field at least once, so that the page really is pinned.
* That's why the refcount from the earlier
* However, be sure to *also* increment the normal page
* refcount field at least once, so that the page really
* is pinned. That's why the refcount from the earlier
* try_get_compound_head() is left intact.
*/
if (hpage_pincount_available(page))
hpage_pincount_add(page, refs);
atomic_add(refs, compound_pincount_ptr(page));
else
page_ref_add(page, refs * (GUP_PIN_COUNTING_BIAS - 1));
@ -222,14 +214,13 @@ bool __must_check try_grab_page(struct page *page, unsigned int flags)
return false;
/*
* Similar to try_grab_compound_head(): even if using the
* hpage_pincount_add/_sub() routines, be sure to
* *also* increment the normal page refcount field at least
* once, so that the page really is pinned.
* Similar to try_grab_compound_head(): be sure to *also*
* increment the normal page refcount field at least once,
* so that the page really is pinned.
*/
if (hpage_pincount_available(page)) {
page_ref_add(page, 1);
hpage_pincount_add(page, 1);
atomic_add(1, compound_pincount_ptr(page));
} else {
page_ref_add(page, GUP_PIN_COUNTING_BIAS);
}