Re: [PATCH v5 01/11] asm-generic/pgtable: Adds generic functions to monitor lockless pgtable walks

From: Leonardo Bras
Date: Wed Oct 09 2019 - 14:11:24 EST

On Fri, 2019-10-04 at 13:28 +0200, Peter Zijlstra wrote:
> > Could you please explain it?
> > I mean, why this breaks tmpfs-thp?
> > Also, why mm_cpumask() is also broken?
> Because shared pages are not bound by a mm; or does it not share the thp
> state between mappings?

By what I could understand, even though the memory is shared, the
mapping may differ for different processes (i.e. the same physical
memory that is mapped as a hugepage in process A can be mapped as a lot
of smallpages in process B).

Did I miss something here?

> And once you (re)figure it out, please write it down. It is a crucial
> bit of the puzzle and needs to be part of the Changelogs.

I am still investing time studying this. More on this later :)


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