linux-kernel - Re: [PATCH RFC] hugetlbfs 'noautofill' mount option

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Message-ID: <b769dc7b-2486-b703-6346-1f80a092cc3f@oracle.com>
Date:   Tue, 27 Jun 2017 13:57:48 -0700
From:   Prakash Sangappa <prakash.sangappa@...cle.com>
To:     Andrea Arcangeli <aarcange@...hat.com>
Cc:     Christoph Hellwig <hch@...radead.org>,
        Dave Hansen <dave.hansen@...el.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Mike Kravetz <mike.kravetz@...cle.com>
Subject: Re: [PATCH RFC] hugetlbfs 'noautofill' mount option



On 6/20/17 4:35 PM, Prakash Sangappa wrote:
>
>
> On 6/16/17 6:15 AM, Andrea Arcangeli wrote:
>> Adding a single if (ctx->feature & UFFD_FEATURE_SIGBUS) goto out,
>> branch for this corner case to handle_userfault() isn't great and the
>> hugetlbfs mount option is absolutely zero cost to the handle_userfault
>> which is primarily why I'm not against it.. although it's not going to
>> be measurable so it would be ok also to add such feature.
>
>
> If implementing UFFD_FEATURE_SIGBUS is preferred instead of the mount 
> option, I could look into that.
>
Implementing UFFD_FEATURE_SIGBUS seems reasonable.

I wanted to note here on this thread that I sent out a seperate
RFC patch review for adding UFFD_FEATURE_SIGBUS.

See,
http://marc.info/?l=linux-mm&m=149857975906880&w=2