Re: [PATCH 0/2] mm/shrinker: make unregister_shrinker() less fragile

From	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 0/2] mm/shrinker: make unregister_shrinker() less fragile
Date	2015-07-13 11:40 +0200
Message-ID	<pLInq-3kU-37@gated-at.bofh.it> (permalink)
References	(1 earlier) <pKZTj-1Tn-11@gated-at.bofh.it> <pLfv3-2G0-1@gated-at.bofh.it> <pLFzb-1F6-7@gated-at.bofh.it> <pLFSy-1Lw-15@gated-at.bofh.it> <pLHUn-3aG-19@gated-at.bofh.it>
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On (07/13/15 02:03), Christoph Hellwig wrote:
> On Mon, Jul 13, 2015 at 03:52:53PM +0900, Sergey Senozhatsky wrote:
> > Why? In some sense, shrinker callbacks are just a way to be nice.
> > No one writes a driver just to be able to handle shrinker calls. An
> > ability to react to those calls is just additional option; it does
> > not directly affect or limit driver's functionality (at least, it
> > really should not).
> 
> No, they are not just nice.  They are a fundamental part of memory
> management and required to reclaim (often large) amounts of memory.

Yes. 'Nice' used in a sense that drivers have logic to release the
memory anyway; mm asks volunteers (the drivers that have registered
shrinker callbacks) to release some spare/wasted/etc. when things
are getting tough (the drivers are not aware of that in general).
This is surely important to mm, not to the driver though -- it just
agrees to be 'nice', but even not expected to release any memory at
all (IOW, this is not a contract).

	-ss
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Re: [PATCH 0/2] mm/shrinker: make unregister_shrinker() less fragile Christoph Hellwig <hch@infradead.org> - 2015-07-11 12:10 +0200
  Re: [PATCH 0/2] mm/shrinker: make unregister_shrinker() less fragile Christoph Hellwig <hch@infradead.org> - 2015-07-13 08:40 +0200
    Re: [PATCH 0/2] mm/shrinker: make unregister_shrinker() less fragile Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2015-07-13 09:00 +0200
      Re: [PATCH 0/2] mm/shrinker: make unregister_shrinker() less fragile Christoph Hellwig <hch@infradead.org> - 2015-07-13 11:10 +0200
        Re: [PATCH 0/2] mm/shrinker: make unregister_shrinker() less fragile Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2015-07-13 11:40 +0200

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