Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.34 as permitted sender) client-ip=23.128.96.34;
Message-ID: <7ddc6ba18b3fef3ed637dcd9a85e90cf4ca6ca7d.camel@surriel.com>
Subject: Re: [PATCH 1/2] hugetlbfs: extend hugetlb_vma_lock to private VMAs
From:   Rik van Riel <riel@surriel.com>
To:     Matthew Wilcox <willy@infradead.org>
Cc:     linux-kernel@vger.kernel.org, kernel-team@meta.com,
        linux-mm@kvack.org, akpm@linux-foundation.org,
        muchun.song@linux.dev, mike.kravetz@oracle.com, leit@meta.com
Date:   Wed, 20 Sep 2023 00:09:41 -0400
In-Reply-To: <ZQptrdK69wvJ2NXP@casper.infradead.org>
References: <20230920021811.3095089-1-riel@surriel.com>
         <20230920021811.3095089-2-riel@surriel.com>
         <ZQptrdK69wvJ2NXP@casper.infradead.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 8BIT
User-Agent: Evolution 3.46.4 (3.46.4-1.fc37) 
MIME-Version: 1.0
Sender: riel@surriel.com
Precedence: bulk

On Wed, 2023-09-20 at 04:57 +0100, Matthew Wilcox wrote:
> On Tue, Sep 19, 2023 at 10:16:09PM -0400, riel@surriel.com wrote:
> > From: Rik van Riel <riel@surriel.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.

-- 
All Rights Reversed.