linux-kernel - Re: [PATCH v7 3/8] mm/rmap: Split try_to_munlock from try_to_unmap

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Message-ID: <1636116.HIPWbOE89B@nvdebian>
Date:   Wed, 31 Mar 2021 09:16:41 +1100
From:   Alistair Popple <apopple@...dia.com>
To:     <dri-devel@...ts.freedesktop.org>
CC:     Jason Gunthorpe <jgg@...dia.com>, <rcampbell@...dia.com>,
        <willy@...radead.org>, <linux-doc@...r.kernel.org>,
        <nouveau@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
        <kvm-ppc@...r.kernel.org>, <hch@...radead.org>,
        <linux-mm@...ck.org>, <jglisse@...hat.com>, <bskeggs@...hat.com>,
        <jhubbard@...dia.com>, <akpm@...ux-foundation.org>,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH v7 3/8] mm/rmap: Split try_to_munlock from try_to_unmap

On Wednesday, 31 March 2021 9:09:30 AM AEDT Alistair Popple wrote:
> On Wednesday, 31 March 2021 5:49:03 AM AEDT Jason Gunthorpe wrote:
> > On Fri, Mar 26, 2021 at 11:08:00AM +1100, Alistair Popple wrote:

<snip>

> > So what clears PG_mlocked on this call path?
> 
> See munlock_vma_page(). munlock works by clearing PG_mlocked, then calling 
> try_to_munlock to check if any VMAs still need it locked in which case 
> PG_mlocked gets set again. There are no other callers of try_to_munlock().
> 
> > Something needs attention here..
> 
> I think the code is correct, but perhaps the naming could be better. Would be 
> interested hearing any thoughts on renaming try_to_munlock() to try_to_mlock() 
> as the current name appears based on the context it is called from (munlock) 
> rather than what it does (mlock).

Actually Documentation/vm/unevictable-lru.rst contains a better suggestion:

try_to_munlock() Reverse Map Scan
---------------------------------

.. warning::
   [!] TODO/FIXME: a better name might be page_mlocked() - analogous to the
   page_referenced() reverse map walker.

Thoughts on renaming try_to_unlock() -> page_mlocked() and try_to_munlock_one() -> page_mlock_one()?

>  - Alistair
> 
> > Jason
> > 
> 
> 
> 
> 
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> 
> 

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