mm, vmalloc: use __GFP_HIGHMEM implicitly

__vmalloc* allows users to provide gfp flags for the underlying
allocation.  This API is quite popular

  $ git grep "=[[:space:]]__vmalloc\|return[[:space:]]*__vmalloc" | wc -l
  77

The only problem is that many people are not aware that they really want
to give __GFP_HIGHMEM along with other flags because there is really no
reason to consume precious lowmemory on CONFIG_HIGHMEM systems for pages
which are mapped to the kernel vmalloc space.  About half of users don't
use this flag, though.  This signals that we make the API unnecessarily
too complex.

This patch simply uses __GFP_HIGHMEM implicitly when allocating pages to
be mapped to the vmalloc space.  Current users which add __GFP_HIGHMEM
are simplified and drop the flag.

Link: http://lkml.kernel.org/r/20170307141020.29107-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Cristopher Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/parisc/kernel/module.c b/arch/parisc/kernel/module.c
index c66c943d9322..f1a76935a314 100644
--- a/arch/parisc/kernel/module.c
+++ b/arch/parisc/kernel/module.c
@@ -218,7 +218,7 @@ void *module_alloc(unsigned long size)
 	 * easier than trying to map the text, data, init_text and
 	 * init_data correctly */
 	return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END,
-				    GFP_KERNEL | __GFP_HIGHMEM,
+				    GFP_KERNEL,
 				    PAGE_KERNEL_RWX, 0, NUMA_NO_NODE,
 				    __builtin_return_address(0));
 }