Why does “page allocation failure” occur whereas there are still “58*4096kB (C)” could be used?

From: 孙世龙 <sunshilong369@gmail.com>
To: Kernelnewbies@kernelnewbies.org
Subject: Why does “page allocation failure” occur whereas there are still “58*4096kB (C)” could be used?
Date: Thu, 18 Jun 2020 14:21:05 +0800	[thread overview]
Message-ID: <CAAvDm6YhTfJusHQ-L+varm_AHciqn4hq-ONW-8w3Yc4Xp49qkA@mail.gmail.com> (raw)

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Hi,

Why does "page allocation failure" occur whereas there are still "58*4096kB
(C)"(*I think it indicates there are 58 order 10 memory could be used*)
could be used?

Here is the related log:

[ 2161.623563] xxxx: page allocation failure: order:10,
mode:0x2084020(GFP_ATOMIC|__GFP_COMP)
[ 2161.632085] CPU: 0 PID: 179 Comm: AiApp Not tainted 4.9.56 #53
[ 2161.637947]
Call Trace:
[<802f63f2>] dump_stack+0x1e/0x3c
[<800f6cf4>] warn_alloc+0x100/0x148
[<800f709c>] __alloc_pages_nodemask+0x2bc/0xb5c
[<801120fe>] kmalloc_order+0x26/0x48
[<80112158>] kmalloc_order_trace+0x38/0x98
[<8012c5d8>] __kmalloc+0xf4/0x12c
[<8048ac78>] alloc_ep_req+0x5c/0x98
[<8048f232>] source_sink_recv+0x2a/0xe0
[<8048f35e>] usb_sourcesink_bulk_read+0x76/0x1c8
[<8048f770>] usb_sourcesink_read+0xfc/0x2c8
[<80134d58>] __vfs_read+0x30/0x108
[<80135c14>] vfs_read+0x94/0x128
[<80136d12>] SyS_read+0x52/0xd4
[<8004a246>] csky_systemcall+0x96/0xe0
[ 2161.689204] Mem-Info:
[ 2161.691518] active_anon:3268 inactive_anon:2 isolated_anon:0
[ 2161.691518]  active_file:1271 inactive_file:89286 isolated_file:0
[ 2161.691518]  unevictable:0 dirty:343 writeback:0 unstable:0
[ 2161.691518]  slab_reclaimable:2019 slab_unreclaimable:644
[ 2161.691518]  mapped:4282 shmem:4 pagetables:59 bounce:0
[ 2161.691518]  free:62086 free_pcp:199 free_cma:60234

[ 2161.724334] Node 0 active_anon:13072kB inactive_anon:8kB
active_file:5084kB inactive_file:357144kB unevictable:0kB
isolated(anon):0kB isolated(file):0kB mapped:17128kB dirty:1372kB
writeback:0kB shmem:16kB writeback_tmp:0kB unstable:0kB
pages_scanned:0 all_unreclaimable? no

[ 2161.748626] Normal free:248344kB min:2444kB low:3052kB high:3660kB
active_anon:13072kB inactive_anon:8kB active_file:5084kB
inactive_file:357144kB unevictable:0kB writepending:1372kB
present:1048572kB managed:734568kB mlocked:0kB slab_reclaimable:8076kB
slab_unreclaimable:2576kB kernel_stack:608kB pagetables:236kB
bounce:0kB free_pcp:796kB local_pcp:796kB free_cma:240936kB
[ 2161.781670] lowmem_reserve[]: 0 0 0

[ 2161.785225] Normal: 4*4kB (UEC) 3*8kB (EC) 3*16kB (UEC) 2*32kB (UE)
2*64kB (UE) 2*128kB (UE) 2*256kB (EC) 1*512kB (E) 3*1024kB (UEC)
3*2048kB (UEC) 58*4096kB (C) = 248344kB
90573 total pagecache pages

[ 2161.803526] 262143 pages RAM
[ 2161.806410] 0 pages HighMem/MovableOnly
[ 2161.810264] 78501 pages reserved
[ 2161.813509] 90112 pages cma reserved

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