Commit 78d9d6ce authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

mm/gup: Remove hpage_pincount_add() 



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: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent 59409373

mm/gup.c

+11 −20
Original line number Diff line number Diff line
@@ -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);

		}