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SubjectRe: Linux 5.9-rc7 / VmallocTotal wrongly reported
Adding Vlastimil, Roman and the kernel mailing list to the cc.

Vlastimil, Roman - this looks like a slab regression. And while others
have touched slab in this merge window, you guys did so more than
most.. Comments?

On Wed, Sep 30, 2020 at 11:55 PM Bastian Bittorf <> wrote:
> Since 5.9-rc1 i can see false values, booting with qemu (128mb RAM):
> / # free
> total used free shared buff/cache available
> Mem: 122176 18014398506028288 114848 0 3461024 3568096

that looks like a negative 64-bit number shifted down by 10 bits (bytes -> kB).

> / # cat /proc/meminfo | grep ^V
> VmallocTotal: 34359738367 kB

.. but this part is normal. VMALLOC_TOTAL is the VM space for vmalloc
areas, and it's large on a 64-bit machine.

And afaik, it hasn't changed in a long time.

So I think there's something else confusing 'free'.

I think it's this:

> / # cat /proc/meminfo
> MemAvailable: 3617184 kB
> Slab: 10321920 kB
> SReclaimable: 3506176 kB
> SUnreclaim: 6815744 kB

because those slab reclaimable/unreclaimable numbers look completely
bogus. You have more unreclaimable slab space than you have memory.

Hmm. I'm not seeing anything similar. And your config looks sane, with
the main difference I see wrt SLAB being that you have


but there's nothing wrong with that either.

It would be lovely if you could bisect it, but maybe Vlastimil or
Roman will go "Ahh, obviously.."


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