linux-kernel - Re: [PATCHv3] mm: Account pud page tables

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Message-ID: <20171004142804.o6vxbjs75x4iyp2r@dhcp22.suse.cz>
Date:   Wed, 4 Oct 2017 16:28:04 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     "Kirill A. Shutemov" <kirill@...temov.name>
Cc:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Vlastimil Babka <vbabka@...e.cz>
Subject: Re: [PATCHv3] mm: Account pud page tables

On Wed 04-10-17 17:16:20, Kirill A. Shutemov wrote:
> On Wed, Oct 04, 2017 at 03:48:53PM +0200, Michal Hocko wrote:
> > On Mon 02-10-17 11:04:27, Kirill A. Shutemov wrote:
> > > On machine with 5-level paging support a process can allocate
> > > significant amount of memory and stay unnoticed by oom-killer and
> > > memory cgroup. The trick is to allocate a lot of PUD page tables.
> > > We don't account PUD page tables, only PMD and PTE.
> > > 
> > > We already addressed the same issue for PMD page tables, see
> > > dc6c9a35b66b ("mm: account pmd page tables to the process").
> > > Introduction 5-level paging bring the same issue for PUD page tables.
> > > 
> > > The patch expands accounting to PUD level.
> > 
> > Can we skip the VmPUD part and reporting puds in the oom report please?
> > I would like to consolidate all levels into a single counter and carying
> > about one less user visible change will make it slightly easier. Or does
> > anybody need this exported to the userspace?
> 
> Let me do this as a separate patch. I will also fold VmPMD into VmPTE.

Thanks!
-- 
Michal Hocko
SUSE Labs