Linux LowFree 和 Slab

Question

目前，My Router 遇到了一种奇怪的情况，即 MemoryFree 不断增长，但在搜索/proc/meminfo 时却没有增长!怎么会这样？

一开始:

MemTotal:         513112 kB
MemFree:          453244 kB
MemAvailable:     397132 kB
Buffers:            3664 kB
Cached:            11428 kB
SwapCached:            0 kB
Active:            10476 kB
Inactive:           8036 kB
Active(anon):       3512 kB
Inactive(anon):     1024 kB
Active(file):       6964 kB
Inactive(file):     7012 kB
Unevictable:           0 kB
Mlocked:               0 kB
HighTotal:         65536 kB
HighFree:          62968 kB
LowTotal:         447576 kB
LowFree:          390276 kB
SwapTotal:             0 kB
SwapFree:              0 kB
Dirty:                 0 kB
Writeback:             0 kB
AnonPages:          3552 kB
Mapped:             3016 kB
Shmem:              1116 kB
Slab:              15412 kB
SReclaimable:       2952 kB
SUnreclaim:        12460 kB
KernelStack:         632 kB
PageTables:          396 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:      256556 kB
Committed_AS:      14288 kB
VmallocTotal:    1015800 kB
VmallocUsed:        7816 kB
VmallocChunk:     990320 kB

几天后:

MemTotal:         513112 kB
MemFree:          298280 kB
MemAvailable:     241060 kB
Buffers:            3068 kB 
Cached:            10700 kB
SwapCached:            0 kB
Active:            11084 kB
Inactive:           6284 kB
Active(anon):       4112 kB
Inactive(anon):     1180 kB
Active(file):       6972 kB
Inactive(file):     5104 kB
Unevictable:           0 kB
Mlocked:               0 kB
HighTotal:         65536 kB
HighFree:          62164 kB
LowTotal:         447576 kB
LowFree:          236116 kB
SwapTotal:             0 kB
SwapFree:              0 kB
Dirty:                 0 kB
Writeback:             0 kB
AnonPages:          3644 kB
Mapped:             3064 kB
Shmem:              1692 kB
Slab:              17224 kB
SReclaimable:       2632 kB
SUnreclaim:        14592 kB
KernelStack:         576 kB
PageTables:          392 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:      256556 kB
Committed_AS:      14904 kB
VmallocTotal:    1015800 kB
VmallocUsed:        7656 kB
VmallocChunk:     952764 kB

由于 SLAB 区域没有发生重大变化，因此泄漏一定不是 kmalloc/kfree API 及其伙伴泄漏的(LowFree 正在向下增长，因此泄漏一定位于内核空间的某处)。有谁能够帮助我？抱歉我的英语不好。

Answer 1

最后发现是MTK WIFI驱动调用dev_alloc_skb分配了一个skb却忘记释放导致的Leak。dev_alloc_skb内部直接通过alloc_pages分配skb->data，不被slab记录。