Commit 44fdffd7 authored Dec 14, 2016 by Alexander Duyck Committed by Linus Torvalds Dec 14, 2016

mm: add support for releasing multiple instances of a page

Add a function that allows us to batch free a page that has multiple
references outstanding.  Specifically this function can be used to drop
a page being used in the page frag alloc cache.  With this drivers can
make use of functionality similar to the page frag alloc cache without
having to do any workarounds for the fact that there is no function that
frees multiple references.

Link: http://lkml.kernel.org/r/20161110113606.76501.70752.stgit@ahduyck-blue-test.jf.intel.com


Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no>
Cc: Helge Deller <deller@gmx.de>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Keguang Zhang <keguang.zhang@gmail.com>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Tobias Klauser <tklauser@distanz.ch>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 0495c3d3

include/linux/gfp.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -506,6 +506,8 @@ extern void free_hot_cold_page(struct page *page, bool cold);
		extern void free_hot_cold_page_list(struct list_head *list, bool cold);

		struct page_frag_cache;
		extern void __page_frag_drain(struct page *page, unsigned int order,
		unsigned int count);
		extern void __alloc_page_frag(struct page_frag_cache nc,
		unsigned int fragsz, gfp_t gfp_mask);
		extern void __free_page_frag(void *addr);

mm/page_alloc.c

+14 −0

Original line number	Diff line number	Diff line
		@@ -3925,6 +3925,20 @@ static struct page __page_frag_refill(struct page_frag_cache nc,
		return page;
		}

		void __page_frag_drain(struct page *page, unsigned int order,
		unsigned int count)
		{
		VM_BUG_ON_PAGE(page_ref_count(page) == 0, page);

		if (page_ref_sub_and_test(page, count)) {
		if (order == 0)
		free_hot_cold_page(page, false);
		else
		__free_pages_ok(page, order);
		}
		}
		EXPORT_SYMBOL(__page_frag_drain);

		void __alloc_page_frag(struct page_frag_cache nc,
		unsigned int fragsz, gfp_t gfp_mask)
		{

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