Re: [PATCH -V2 0/9] memcg: add HugeTLB resource tracking

On Thu,  1 Mar 2012 14:46:11 +0530
"Aneesh Kumar K.V" [off-list ref] wrote:

This patchset implements a memory controller extension to control
HugeTLB allocations. It is similar to the existing hugetlb quota
support in that, the limit is enforced at mmap(2) time and not at
fault time. HugeTLB's quota mechanism limits the number of huge pages
that can allocated per superblock.

For shared mappings we track the regions mapped by a task along with the
memcg. We keep the memory controller charged even after the task
that did mmap(2) exits. Uncharge happens during truncate. For Private
mappings we charge and uncharge from the current task cgroup.

I haven't begin to get my head around this yet, but I'd like to draw
your attention to https://lkml.org/lkml/2012/2/15/548.  That fix has
been hanging around for a while, but I haven't done anything with it
yet because I don't like its additional blurring of the separation
between hugetlb core code and hugetlbfs.  I want to find time to sit
down and see if the fix can be better architected but haven't got
around to that yet.

I expect that your patches will conflict at least mechanically with
David's, which is not a big issue.  But I wonder whether your patches
will copy the same bug into other places, and whether you can think of
a tidier way of addressing the bug which David is seeing?

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