Messages in this thread | | | Date | Wed, 13 Feb 2019 17:53:14 -0800 | From | Ira Weiny <> | Subject | Re: [PATCH 0/5] use pinned_vm instead of locked_vm to account pinned pages |
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On Mon, Feb 11, 2019 at 03:54:47PM -0700, Jason Gunthorpe wrote: > On Mon, Feb 11, 2019 at 05:44:32PM -0500, Daniel Jordan wrote: > > > All five of these places, and probably some of Davidlohr's conversions, > > probably want to be collapsed into a common helper in the core mm for > > accounting pinned pages. I tried, and there are several details that > > likely need discussion, so this can be done as a follow-on. > > I've wondered the same..
I'm really thinking this would be a nice way to ensure it gets cleaned up and does not happen again.
Also, by moving it to the core we could better manage any user visible changes.
From a high level, pinned is a subset of locked so it seems like we need a 2 sets of helpers.
try_increment_locked_vm(...) decrement_locked_vm(...)
try_increment_pinned_vm(...) decrement_pinned_vm(...)
Where try_increment_pinned_vm() also increments locked_vm... Of course this may end up reverting the improvement of Davidlohr Bueso's atomic work... :-(
Furthermore it would seem better (although I don't know if at all possible) if this were accounted for in core calls which tracked them based on how the pages are being used so that drivers can't call try_increment_locked_vm() and then pin the pages... Thus getting the account wrong vs what actually happened.
And then in the end we can go back to locked_vm being the value checked against RLIMIT_MEMLOCK.
Ira
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