target/linux/generic/backport-4.9/040-mm-add-support-for-releasing-multiple-instances-of-a.patch

   1 From: Alexander Duyck <alexander.h.duyck@intel.com>
   2 Date: Wed, 14 Dec 2016 15:05:26 -0800
   3 Subject: [PATCH] mm: add support for releasing multiple instances of a page
   4
   5 Add a function that allows us to batch free a page that has multiple
   6 references outstanding.  Specifically this function can be used to drop
   7 a page being used in the page frag alloc cache.  With this drivers can
   8 make use of functionality similar to the page frag alloc cache without
   9 having to do any workarounds for the fact that there is no function that
  10 frees multiple references.
  11
  12 Link: http://lkml.kernel.org/r/20161110113606.76501.70752.stgit@ahduyck-blue-test.jf.intel.com
  13 Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
  14 Cc: "David S. Miller" <davem@davemloft.net>
  15 Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
  16 Cc: Chris Metcalf <cmetcalf@mellanox.com>
  17 Cc: David Howells <dhowells@redhat.com>
  18 Cc: Geert Uytterhoeven <geert@linux-m68k.org>
  19 Cc: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no>
  20 Cc: Helge Deller <deller@gmx.de>
  21 Cc: James Hogan <james.hogan@imgtec.com>
  22 Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
  23 Cc: Jonas Bonn <jonas@southpole.se>
  24 Cc: Keguang Zhang <keguang.zhang@gmail.com>
  25 Cc: Ley Foon Tan <lftan@altera.com>
  26 Cc: Mark Salter <msalter@redhat.com>
  27 Cc: Max Filippov <jcmvbkbc@gmail.com>
  28 Cc: Michael Ellerman <mpe@ellerman.id.au>
  29 Cc: Michal Simek <monstr@monstr.eu>
  30 Cc: Ralf Baechle <ralf@linux-mips.org>
  31 Cc: Rich Felker <dalias@libc.org>
  32 Cc: Richard Kuo <rkuo@codeaurora.org>
  33 Cc: Russell King <linux@armlinux.org.uk>
  34 Cc: Steven Miao <realmz6@gmail.com>
  35 Cc: Tobias Klauser <tklauser@distanz.ch>
  36 Cc: Vineet Gupta <vgupta@synopsys.com>
  37 Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
  38 Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
  39 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
  40 ---
  41
  42 --- a/include/linux/gfp.h
  43 +++ b/include/linux/gfp.h
  44 @@ -506,6 +506,8 @@ extern void free_hot_cold_page(struct pa
  45  extern void free_hot_cold_page_list(struct list_head *list, bool cold);
  46
  47  struct page_frag_cache;
  48 +extern void __page_frag_drain(struct page *page, unsigned int order,
  49 +                             unsigned int count);
  50  extern void *__alloc_page_frag(struct page_frag_cache *nc,
  51                                unsigned int fragsz, gfp_t gfp_mask);
  52  extern void __free_page_frag(void *addr);
  53 --- a/mm/page_alloc.c
  54 +++ b/mm/page_alloc.c
  55 @@ -3945,6 +3945,20 @@ static struct page *__page_frag_refill(s
  56         return page;
  57  }
  58
  59 +void __page_frag_drain(struct page *page, unsigned int order,
  60 +                      unsigned int count)
  61 +{
  62 +       VM_BUG_ON_PAGE(page_ref_count(page) == 0, page);
  63 +
  64 +       if (page_ref_sub_and_test(page, count)) {
  65 +               if (order == 0)
  66 +                       free_hot_cold_page(page, false);
  67 +               else
  68 +                       __free_pages_ok(page, order);
  69 +       }
  70 +}
  71 +EXPORT_SYMBOL(__page_frag_drain);
  72 +
  73  void *__alloc_page_frag(struct page_frag_cache *nc,
  74                         unsigned int fragsz, gfp_t gfp_mask)
  75  {