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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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.