Messages in this thread | | | Date | Fri, 8 Jun 2018 12:57:17 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] mm/madvise: allow MADV_DONTNEED to free memory that is MLOCK_ONFAULT |
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On Fri, 8 Jun 2018 14:56:52 -0400 Jason Baron <jbaron@akamai.com> wrote:
> In order to free memory that is marked MLOCK_ONFAULT, the memory region > needs to be first unlocked, before calling MADV_DONTNEED. And if the region > is to be reused as MLOCK_ONFAULT, we require another call to mlock2() with > the MLOCK_ONFAULT flag. > > Let's simplify freeing memory that is set MLOCK_ONFAULT, by allowing > MADV_DONTNEED to work directly for memory that is set MLOCK_ONFAULT. The > locked memory limits, tracked by mm->locked_vm do not need to be adjusted > in this case, since they were charged to the entire region when > MLOCK_ONFAULT was initially set.
Seems useful.
Is a manpage update planned?
Various updates to tools/testing/selftests/vm/* seem appropriate.
> Further, I don't think allowing MADV_FREE for MLOCK_ONFAULT regions makes > sense, since the point of MLOCK_ONFAULT is for userspace to know when pages > are locked in memory and thus to know when page faults will occur.
This sounds non-backward-compatible?
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