mm/page_alloc: fix memalloc_nocma_{save/restore} APIs
authorJoonsoo Kim <iamjoonsoo.kim@lge.com>
Fri, 7 Aug 2020 06:26:04 +0000 (23:26 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 7 Aug 2020 18:33:29 +0000 (11:33 -0700)
commit8510e69c8efef82f2b37ea3e8ea19a27122c533e
tree41e4a0fc437e4e723bece37ca7ebc8005c26c68f
parent182f3d7a02fddd9e4b1181c2ba710a930e05ddbb
mm/page_alloc: fix memalloc_nocma_{save/restore} APIs

Currently, memalloc_nocma_{save/restore} API that prevents CMA area
in page allocation is implemented by using current_gfp_context(). However,
there are two problems of this implementation.

First, this doesn't work for allocation fastpath. In the fastpath,
original gfp_mask is used since current_gfp_context() is introduced in
order to control reclaim and it is on slowpath. So, CMA area can be
allocated through the allocation fastpath even if
memalloc_nocma_{save/restore} APIs are used. Currently, there is just
one user for these APIs and it has a fallback method to prevent actual
problem.
Second, clearing __GFP_MOVABLE in current_gfp_context() has a side effect
to exclude the memory on the ZONE_MOVABLE for allocation target.

To fix these problems, this patch changes the implementation to exclude
CMA area in page allocation. Main point of this change is using the
alloc_flags. alloc_flags is mainly used to control allocation so it fits
for excluding CMA area in allocation.

Fixes: d7fefcc8de91 (mm/cma: add PF flag to force non cma alloc)
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Link: http://lkml.kernel.org/r/1595468942-29687-1-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/sched/mm.h
mm/page_alloc.c