Date: Tue, 12 Sep 2017 23:10:39 +0200
From: Alexandru Moise <00moses.alexander00@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, khandual@linux.vnet.ibm.com,
        mhocko@suse.com, aarcange@redhat.com, minchan@kernel.org,
        hillf.zj@alibaba-inc.com, shli@fb.com, rppt@linux.vnet.ibm.com,
        kirill.shutemov@linux.intel.com, mgorman@techsingularity.net,
        rientjes@google.com, riel@redhat.com, linux-mm@kvack.org
Subject: Re: [PATCH] mm, hugetlb, soft_offline: save compound page order
 before page migration
Message-ID: <20170912211039.GA16850@gmail.com>
References: <20170912204306.GA12053@gmail.com>
 <20170912135448.341359676c6f8045f4a622f0@linux-foundation.org>
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On Tue, Sep 12, 2017 at 01:54:48PM -0700, Andrew Morton wrote:
> On Tue, 12 Sep 2017 22:43:06 +0200 Alexandru Moise <00moses.alexander00@gmail.com> wrote:
> 
> > This fixes a bug in madvise() where if you'd try to soft offline a
> > hugepage via madvise(), while walking the address range you'd end up,
> > using the wrong page offset due to attempting to get the compound
> > order of a former but presently not compound page, due to dissolving
> > the huge page (since c3114a8).
> 
> What are the user visible effects of the bug?  The wrong page is
> offlined?  No offlining occurs?  

I end up with all my free pages getting offlined. Except 1.

../Alex