mm: skip CMA pages when they are not available

mm: skip CMA pages when they are not available

This patch fixes unproductive reclaiming of CMA pages by skipping them
when they are not available for current context.  It arises from the below
OOM issue, which was caused by a large proportion of MIGRATE_CMA pages
among free pages.

[   36.172486] [03-19 10:05:52.172] ActivityManager: page allocation failure: order:0, mode:0xc00(GFP_NOIO), nodemask=(null),cpuset=foreground,mems_allowed=0
[   36.189447] [03-19 10:05:52.189] DMA32: 0*4kB 447*8kB (C) 217*16kB (C) 124*32kB (C) 136*64kB (C) 70*128kB (C) 22*256kB (C) 3*512kB (C) 0*1024kB 0*2048kB 0*4096kB = 35848kB
[   36.193125] [03-19 10:05:52.193] Normal: 231*4kB (UMEH) 49*8kB (MEH) 14*16kB (H) 13*32kB (H) 8*64kB (H) 2*128kB (H) 0*256kB 1*512kB (H) 0*1024kB 0*2048kB 0*4096kB = 3236kB
...
[   36.234447] [03-19 10:05:52.234] SLUB: Unable to allocate memory on node -1, gfp=0xa20(GFP_ATOMIC)
[   36.234455] [03-19 10:05:52.234] cache: ext4_io_end, object size: 64, buffer size: 64, default order: 0, min order: 0
[   36.234459] [03-19 10:05:52.234] node 0: slabs: 53,objs: 3392, free: 0

This change further decreases the chance for wrong OOMs in the presence
of a lot of CMA memory.

[david@redhat.com: changelog addition]
Link: https://lkml.kernel.org/r/1685501461-19290-1-git-send-email-zhaoyang.huang@unisoc.com
Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: ke.wang <ke.wang@unisoc.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>