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Subject: Re: [PATCH] hugetlbfs: Take read_lock on i_mmap for PMD sharing
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Mike Kravetz <mike.kravetz@oracle.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Davidlohr Bueso <dave@stgolabs.net>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Will Deacon <will.deacon@arm.com>
References: <20191107190628.22667-1-longman@redhat.com>
 <20191107194225.GE11823@bombadil.infradead.org>
From:   Waiman Long <longman@redhat.com>
Organization: Red Hat
Message-ID: <2d4b12a7-ea30-fe33-f59d-342346dfdec9@redhat.com>
Date:   Thu, 7 Nov 2019 16:06:47 -0500
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On 11/7/19 2:42 PM, Matthew Wilcox wrote:
> On Thu, Nov 07, 2019 at 02:06:28PM -0500, Waiman Long wrote:
>> -=09i_mmap_lock_write(mapping);
>> +=09/*
>> +=09 * PMD sharing does not require changes to i_mmap. So a read lock
>> +=09 * is enuogh.
>> +=09 */
>> +=09i_mmap_lock_read(mapping);
> We don't have comments before any of the other calls to i_mmap_lock_read(=
)
> justifying why we don't need the write lock.  I don't understand why this
> situation is different.  Just delete the comment and make this a two-line
> patch.
>
I am fine with that.

I will send a v2 patch.

Cheers,
Longman