Re: [PATCH -next] mm: make sure freeram is smaller than totalram

[David Hildenbrand (Arm)]

On 4/13/26 13:57, Yang Yingliang wrote:
> The memory stat is not done in real time, it have some gap with
> real value. In CPU-less NUMA node, the values of MemTotal and
> MemFree can be nearly equal, the gap may cause MemFree bigger
> than MemTotal, it leads MemUsed is negative which print as a large
> positive number.

How does this interact with CPU-less NUMA node? Some concurrent memory
hotunplug, or how could be possible get MemFree that is larger than
MemTotal?

> 
> cat /sys/devices/system/node/node17/meminfo
> Node 17 MemTotal:        4194304 kB
> Node 17 MemFree:         4195552 kB
> Node 17 MemUsed:        18446744073709550368 kB
> Node 17 Active:               52 kB
> Node 17 Inactive:            320 kB
> Node 17 Active(anon):          0 kB
> Node 17 Inactive(anon):        0 kB
> Node 17 Active(file):         52 kB
> Node 17 Inactive(file):      320 kB
> Node 17 Unevictable:           0 kB
> Node 17 Mlocked:               0 kB
> Node 17 Dirty:                 0 kB
> Node 17 Writeback:             0 kB
> Node 17 FilePages:           372 kB
> Node 17 Mapped:              320 kB
> Node 17 AnonPages:             0 kB
> Node 17 Shmem:                 0 kB
> Node 17 KernelStack:           0 kB
> Node 17 PageTables:            0 kB
> Node 17 NFS_Unstable:          0 kB
> Node 17 Bounce:                0 kB
> Node 17 WritebackTmp:          0 kB
> Node 17 KReclaimable:          0 kB
> Node 17 Slab:                  0 kB
> Node 17 SReclaimable:          0 kB
> Node 17 SUnreclaim:            0 kB
> Node 17 AnonHugePages:     79872 kB
> Node 17 ShmemHugePages:        0 kB
> Node 17 ShmemPmdMapped:        0 kB
> Node 17 FileHugePages:        0 kB
> Node 17 FilePmdMapped:        0 kB
> Node 17 HugePages_Total:     0
> Node 17 HugePages_Free:      0
> Node 17 HugePages_Surp:      0
> 
> To avoid this exception by refreshing vm_stat, when MemFree
> is bigger than MemTotal.
> 

-- 
Cheers,

David