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Date:   Thu, 7 Nov 2019 19:22:02 -0800
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Davidlohr Bueso <dave@stgolabs.net>
Cc:     Mike Kravetz <mike.kravetz@oracle.com>,
        Matthew Wilcox <willy@infradead.org>,
        Waiman Long <longman@redhat.com>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Will Deacon <will.deacon@arm.com>
Subject: Re: [PATCH] hugetlbfs: Take read_lock on i_mmap for PMD sharing
Message-Id: <20191107192202.8869589f225132480d77a33b@linux-foundation.org>
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On Thu, 7 Nov 2019 18:04:56 -0800 Davidlohr Bueso <dave@stgolabs.net> wrote:

> On Thu, 07 Nov 2019, Mike Kravetz wrote:
> 
> >Note that huge_pmd_share now increments the page count with the semaphore
> >held just in read mode.  It is OK to do increments in parallel without
> >synchronization.  However, we don't want anyone else changing the count
> >while that check in huge_pmd_unshare is happening.  Hence, the need for
> >taking the semaphore in write mode.
> 
> This would be a nice addition to the changelog methinks.

Done.