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SubjectRe: [PATCH 1/6] mm: change locked_vm's type from unsigned long to atomic64_t
On Tue, Apr 02, 2019 at 04:43:57PM -0700, Davidlohr Bueso wrote:
> On Tue, 02 Apr 2019, Andrew Morton wrote:
>
> > Also, we didn't remove any down_write(mmap_sem)s from core code so I'm
> > thinking that the benefit of removing a few mmap_sem-takings from a few
> > obscure drivers (sorry ;)) is pretty small.
>
> afaik porting the remaining incorrect users of locked_vm to pinned_vm was
> the next step before this one, which made converting locked_vm to atomic
> hardly worth it. Daniel?

Right, as you know I tried those incorrect users first, but there were concerns
about user-visible changes regarding RLIMIT_MEMLOCK and pinned_vm/locked_vm
without the accounting problem between all three being solved.

To my knowledge no one has a solution for that, so in the meantime I'm taking
the incremental step of getting rid of mmap_sem for locked_vm users. The
locked_vm -> pinned_vm conversion can happen later.

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