[Linux][Kernel][Memory] smbd: page allocation failure. order:2, mode:0x20

如果啟動了 Jumbo Frame 加上執行 Samba , 有可能會出現類似的訊息(系統抓下來似乎有點不全)

smbd: page allocation failure. order:2, mode:0x20
[<c002fd30>] (dump_backtrace+0x0/0x108) from [<c02ac488>] (dump_stack+0x18/0x1c)
[<c02ac470>] (dump_stack+0x0/0x1c) from [<c0075734>] (__alloc_pages_nodemask+0x3d0/0x55c)
[<c0075364>] (__alloc_pages_nodemask+0x0/0x55c) from [<c008f5d8>] (cache_alloc_refill+0x2b0/0x598)
[<c008f328>] (cache_alloc_refill+0x0/0x598) from [<c008f978>] (__kmalloc+0xb8/0xd8)
[<c008f8c0>] (__kmalloc+0x0/0xd8) from [<c0227a6c>] (__alloc_skb+0x54/0x138)
[<c0227a18>] (__alloc_skb+0x0/0x138) from [<c022879c>] (dev_alloc_skb+0x20/0x44)
[<c022877c>] (dev_alloc_skb+0x0/0x44) from [<c01e643c>] (cns3xxx_receive_packet+0x228/0x3c8)
[<c01e6214>] (cns3xxx_receive_packet+0x0/0x3c8) from [<c01e661c>] (cns3xxx_poll+0x40/0xd4)
[<c01e65dc>] (cns3xxx_poll+0x0/0xd4) from [<c022f264>] (net_rx_action+0xb4/0x184)
[<c022f1b0>] (net_rx_action+0x0/0x184) from [<c0048544>] (__do_softirq+0x90/0x11c)
[<c00484b4>] (__do_softirq+0x0/0x11c) from [<c0048614>] (irq_exit+0x44/0x4c)
[<c00485d0>] (irq_exit+0x0/0x4c) from [<c002b04c>] (_text+0x4c/0x90)
[<c002b000>] (_text+0x0/0x90) from [<c002bab8>] (__irq_svc+0x38/0x80)
Exception stack(0xc7acbcc0 to 0xc7acbd08)
bcc0: c7acbd1c c7829960 c7acbd28 00000000 00000001 c7b53980 c7b539e4 c7acbd1c
bce0: 00000000 00000000 c7acbf08 c7acbd14 c7acbd28 c7acbd08 c0222314 c0057a0c
bd00: 60000013 ffffffff
[<c00579b0>] (finish_wait+0x0/0x6c) from [<c0222314>] (sk_wait_data+0xcc/0xec)
[<c0222248>] (sk_wait_data+0x0/0xec) from [<c0255fc0>] (tcp_recvmsg+0x600/0x8a8)
[<c02559c0>] (tcp_recvmsg+0x0/0x8a8) from [<c0221208>] (sock_common_recvmsg+0x48/0x5c)
[<c02211c0>] (sock_common_recvmsg+0x0/0x5c) from [<c021e7d8>] (sock_aio_read+0x138/0x144)
[<c021e6a0>] (sock_aio_read+0x0/0x144) from [<c0092918>] (do_sync_read+0xc4/0x110)
[<c0092854>] (do_sync_read+0x0/0x110) from [<c00936ac>] (vfs_read+0x164/0x16c)
[<c0093548>] (vfs_read+0x0/0x16c) from [<c0093790>] (sys_read+0x44/0x74)
[<c009374c>] (sys_read+0x0/0x74) from [<c002be40>] (ret_fast_syscall+0x0/0x2c)
Normal per-cpu:
CPU    0: hi:   42, btch:   7 usd:  32
Active_anon:570 active_file:9598 inactive_anon:576
inactive_file:17657 unevictable:0 dirty:3503 writeback:0 unstable:0
free:419 slab:2389 mapped:1587 pagetables:87 bounce:0
Normal free:1676kB min:1440kB low:1800kB high:2160kB active_anon:2280kB inactive_anon:2304kB active_file:38392kB inactive_file:70628kB unevictable:0kB present:130048kB pages_scanned:0 all_unreclaimable? no
lowmem_reserve[]: 0 0
Normal: 345*4kB 25*8kB 6*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 1676kB
27277 total pagecache pages
32768 pages of RAM
543 free pages
1251 reserved pages
2389 slab pages
29382 pages shared
0 pages swap cached

可以加大 kernel 預留的 Buffer, 我系統上原來是 1117, 可以用指令

echo 8192 > /proc/sys/vm/min_free_kbytes

加大到 8Mbytes, 這樣可以減少 page allocation 失敗的機率, 在我們的測試內, 某些時候 8MByte 仍會出現, 可以考慮加大到 16Mbytes.

原因是因為在 interrupt 中, 向系統一次要求大塊的記憶體. 這時可以透過增加 min_free_kbytes 參數去避過這個問題.
調整 slab 的參數或許也有用 ( echo x y z > /proc/slab)


On this day..

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