linux-kernel - Re: [PATCH 1/2] hugetlbfs: extend hugetlb_vma

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Date:   Wed, 20 Sep 2023 09:36:50 -0700
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     Rik van Riel <riel@...riel.com>
Cc:     Matthew Wilcox <willy@...radead.org>, linux-kernel@...r.kernel.org,
        kernel-team@...a.com, linux-mm@...ck.org,
        akpm@...ux-foundation.org, muchun.song@...ux.dev, leit@...a.com
Subject: Re: [PATCH 1/2] hugetlbfs: extend hugetlb_vma_lock to private VMAs

On 09/20/23 00:09, Rik van Riel wrote:
> On Wed, 2023-09-20 at 04:57 +0100, Matthew Wilcox wrote:
> > On Tue, Sep 19, 2023 at 10:16:09PM -0400, riel@...riel.com wrote:
> > > From: Rik van Riel <riel@...riel.com>
> > > 
> > > Extend the locking scheme used to protect shared hugetlb mappings
> > > from truncate vs page fault races, in order to protect private
> > > hugetlb mappings (with resv_map) against MADV_DONTNEED.
> > > 
> > > Add a read-write semaphore to the resv_map data structure, and
> > > use that from the hugetlb_vma_(un)lock_* functions, in preparation
> > > for closing the race between MADV_DONTNEED and page faults.
> > 
> > This feels an awful lot like the invalidate_lock in struct
> > address_space
> > which was recently added by Jan Kara.
> > 
> Indeed it does.
> 
> It might be even nicer if we could replace the hugetlb_vma_lock
> special logic with the invalidate_lock for hugetlbfs.
> 
> Mike, can you think of any reason why the hugetlb_vma_lock logic
> should not be replaced with the invalidate_lock?
> 
> If not, I'd be happy to implement that.
> 

Sorry Rik,

I have some other things that need immediate attention and have not had a
chance to take a close look here.  I'll take a closer look later (my) today
or tomorrow.
-- 
Mike Kravetz