arm64: get rid of superfluous __GFP_REPEAT
authorMichal Hocko <mhocko@suse.com>
Fri, 24 Jun 2016 21:48:56 +0000 (14:48 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sat, 25 Jun 2016 00:23:52 +0000 (17:23 -0700)
commitf3610a6aff7dd70b788364255c0cbc128488ef72
treef4718ba9e2e6f512f8725cf4482d8cfb8760fb85
parentf58f230a832ba8220a64f44aaafcce4b7358d826
arm64: get rid of superfluous __GFP_REPEAT

__GFP_REPEAT has a rather weak semantic but since it has been introduced
around 2.6.12 it has been ignored for low order allocations.

{pte,pmd,pud}_alloc_one{_kernel}, late_pgtable_alloc use PGALLOC_GFP for
__get_free_page (aka order-0).

pgd_alloc is slightly more complex because it allocates from pgd_cache
if PGD_SIZE != PAGE_SIZE and PGD_SIZE depends on the configuration
(CONFIG_ARM64_VA_BITS, PAGE_SHIFT and CONFIG_PGTABLE_LEVELS).

As per
config PGTABLE_LEVELS
int
default 2 if ARM64_16K_PAGES && ARM64_VA_BITS_36
default 2 if ARM64_64K_PAGES && ARM64_VA_BITS_42
default 3 if ARM64_64K_PAGES && ARM64_VA_BITS_48
default 3 if ARM64_4K_PAGES && ARM64_VA_BITS_39
default 3 if ARM64_16K_PAGES && ARM64_VA_BITS_47
default 4 if !ARM64_64K_PAGES && ARM64_VA_BITS_48

we should have the following options

  CONFIG_ARM64_VA_BITS:48 CONFIG_PGTABLE_LEVELS:4 PAGE_SIZE:4k size:4096 pages:1
  CONFIG_ARM64_VA_BITS:48 CONFIG_PGTABLE_LEVELS:4 PAGE_SIZE:16k size:16 pages:1
  CONFIG_ARM64_VA_BITS:48 CONFIG_PGTABLE_LEVELS:3 PAGE_SIZE:64k size:512 pages:1
  CONFIG_ARM64_VA_BITS:47 CONFIG_PGTABLE_LEVELS:3 PAGE_SIZE:16k size:16384 pages:1
  CONFIG_ARM64_VA_BITS:42 CONFIG_PGTABLE_LEVELS:2 PAGE_SIZE:64k size:65536 pages:1
  CONFIG_ARM64_VA_BITS:39 CONFIG_PGTABLE_LEVELS:3 PAGE_SIZE:4k size:4096 pages:1
  CONFIG_ARM64_VA_BITS:36 CONFIG_PGTABLE_LEVELS:2 PAGE_SIZE:16k size:16384 pages:1

All of them fit into a single page (aka order-0).  This means that this
flag has never been actually useful here because it has always been used
only for PAGE_ALLOC_COSTLY requests.

Link: http://lkml.kernel.org/r/1464599699-30131-6-git-send-email-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
arch/arm64/include/asm/pgalloc.h