Re: [PATCH] mm: disable `vm.max_map_count' sysctl limit

[Mikael Pettersson]

On Mon, Nov 27, 2017 at 5:22 PM, Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
>> Could you be more explicit about _why_ we need to remove this tunable?
>> I am not saying I disagree, the removal simplifies the code but I do not
>> really see any justification here.
>
> I imagine he started seeing random syscalls failing with ENOMEM and
> eventually tracked it down to this stupid limit we used to need.

Exactly, except the origin (mmap() failing) was hidden behind layers upon layers
of user-space memory management code (not ours), which just said "failed to
allocate N bytes" (with N about 0.001% of the free RAM).  And it
wasn't reproducible.