From: Alexandru Moise <00moses.alexander00@gmail.com>
To: 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
Date: Tue, 12 Sep 2017 23:12:50 +0200 [thread overview]
Message-ID: <20170912211250.GB16850@gmail.com> (raw)
In-Reply-To: <20170912135835.0b48340ead5570e50529f676@linux-foundation.org>
On Tue, Sep 12, 2017 at 01:58:35PM -0700, Andrew Morton wrote:
> On Tue, 12 Sep 2017 13:54:48 -0700 Andrew Morton <akpm@linux-foundation.org> 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?
>
> This also affects MADV_HWPOISON?
No, MADV_HWPOISON is ok because it doesn't dissolve the hugepage, so the page
remains a compound page the 2nd loop around.
../Alex
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WARNING: multiple messages have this Message-ID (diff)
From: Alexandru Moise <00moses.alexander00@gmail.com>
To: 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
Date: Tue, 12 Sep 2017 23:12:50 +0200 [thread overview]
Message-ID: <20170912211250.GB16850@gmail.com> (raw)
In-Reply-To: <20170912135835.0b48340ead5570e50529f676@linux-foundation.org>
On Tue, Sep 12, 2017 at 01:58:35PM -0700, Andrew Morton wrote:
> On Tue, 12 Sep 2017 13:54:48 -0700 Andrew Morton <akpm@linux-foundation.org> 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?
>
> This also affects MADV_HWPOISON?
No, MADV_HWPOISON is ok because it doesn't dissolve the hugepage, so the page
remains a compound page the 2nd loop around.
../Alex
next prev parent reply other threads:[~2017-09-12 21:12 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-12 20:43 [PATCH] mm, hugetlb, soft_offline: save compound page order before page migration Alexandru Moise
2017-09-12 20:43 ` Alexandru Moise
2017-09-12 20:54 ` Andrew Morton
2017-09-12 20:54 ` Andrew Morton
2017-09-12 20:58 ` Andrew Morton
2017-09-12 20:58 ` Andrew Morton
2017-09-12 21:12 ` Alexandru Moise [this message]
2017-09-12 21:12 ` Alexandru Moise
2017-09-12 21:10 ` Alexandru Moise
2017-09-12 21:10 ` Alexandru Moise
2017-09-13 0:13 ` Naoya Horiguchi
2017-09-13 0:13 ` Naoya Horiguchi
2017-09-13 8:32 ` Alexandru Moise
2017-09-13 8:32 ` Alexandru Moise
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