From: Michal Hocko <mhocko@suse.com>
To: Mike Rapoport <rppt@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
Borislav Petkov <bp@alien8.de>,
Catalin Marinas <catalin.marinas@arm.com>,
Christopher Lameter <cl@linux.com>,
Dan Williams <dan.j.williams@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
David Hildenbrand <david@redhat.com>,
Elena Reshetova <elena.reshetova@intel.com>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
James Bottomley <jejb@linux.ibm.com>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Matthew Wilcox <willy@infradead.org>,
Mark Rutland <mark.rutland@arm.com>,
Mike Rapoport <rppt@linux.ibm.com>,
Michael Kerrisk <mtk.manpages@gmail.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Peter Zijlstra <peterz@infradead.org>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
Roman Gushchin <guro@fb.com>, Shakeel Butt <shakeelb@google.com>,
Shuah Khan <shuah@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Tycho Andersen <tycho@tycho.ws>, Will Deacon <will@kernel.org>,
linux-api@vger.kernel.org, linux-arch@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-nvdimm@lists.01.org, linux-riscv@lists.infradead.org,
x86@kernel.org, Hagen Paul Pfeifer <hagen@jauu.net>,
Palmer Dabbelt <palmerdabbelt@google.com>
Subject: Re: [PATCH v16 08/11] secretmem: add memcg accounting
Date: Tue, 26 Jan 2021 10:15:27 +0100 [thread overview]
Message-ID: <20210126091527.GG827@dhcp22.suse.cz> (raw)
In-Reply-To: <20210126085654.GO6332@kernel.org>
On Tue 26-01-21 10:56:54, Mike Rapoport wrote:
> On Tue, Jan 26, 2021 at 08:31:42AM +0100, Michal Hocko wrote:
> > On Mon 25-01-21 23:38:17, Mike Rapoport wrote:
> > > On Mon, Jan 25, 2021 at 05:54:51PM +0100, Michal Hocko wrote:
> > > > On Thu 21-01-21 14:27:20, Mike Rapoport wrote:
> > > > > From: Mike Rapoport <rppt@linux.ibm.com>
> > > > >
> > > > > Account memory consumed by secretmem to memcg. The accounting is updated
> > > > > when the memory is actually allocated and freed.
> > > >
> > > > What does this mean?
> > >
> > > That means that the accounting is updated when secretmem does cma_alloc()
> > > and cma_relase().
> > >
> > > > What are the lifetime rules?
> > >
> > > Hmm, what do you mean by lifetime rules?
> >
> > OK, so let's start by reservation time (mmap time right?) then the
> > instantiation time (faulting in memory). What if the calling process of
> > the former has a different memcg context than the later. E.g. when you
> > send your fd or inherited fd over fork will move to a different memcg.
> >
> > What about freeing path? E.g. when you punch a hole in the middle of
> > a mapping?
> >
> > Please make sure to document all this.
>
> So, does something like this answer your question:
>
> ---
> The memory cgroup is charged when secremem allocates pages from CMA to
> increase large pages pool during ->fault() processing.
OK so that is when the memory is faulted in. Good that is a standard
model we have. The memcg context of the creator of the secret memory is
not really important. So whoever has created is not charged.
> The pages are uncharged from memory cgroup when they are released back to
> CMA at the time secretme inode is evicted.
> ---
so effectivelly when they are unmapped, right? This is similar to
anonymous memory.
As I've said it would be really great to have this life cycle documented
properly.
> > Please note that this all is a user visible stuff that will become PITA
> > (if possible) to change later on. You should really have strong
> > arguments in your justification here.
>
> I think that adding a dedicated counter for few 2M areas per container is
> not worth the churn.
What kind of churn you have in mind? What is the downside?
> When we'll get to the point that secretmem can be used to back the entire
> guest memory we can add a new counter and it does not seem to PITA to me.
What does really prevent a larger use with this implementation?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2021-01-26 9:15 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-21 12:27 [PATCH v16 00/11] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
2021-01-21 12:27 ` [PATCH v16 01/11] mm: add definition of PMD_PAGE_ORDER Mike Rapoport
2021-01-21 12:27 ` [PATCH v16 02/11] mmap: make mlock_future_check() global Mike Rapoport
2021-01-21 12:27 ` [PATCH v16 03/11] riscv/Kconfig: make direct map manipulation options depend on MMU Mike Rapoport
2021-01-21 12:27 ` [PATCH v16 04/11] set_memory: allow set_direct_map_*_noflush() for multiple pages Mike Rapoport
2021-01-21 12:27 ` [PATCH v16 05/11] set_memory: allow querying whether set_direct_map_*() is actually enabled Mike Rapoport
2021-01-21 12:27 ` [PATCH v16 06/11] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
2021-01-25 17:01 ` Michal Hocko
2021-01-25 21:36 ` Mike Rapoport
2021-01-26 7:16 ` Michal Hocko
2021-01-26 8:33 ` Mike Rapoport
2021-01-26 9:00 ` Michal Hocko
2021-01-26 9:20 ` Mike Rapoport
2021-01-26 9:49 ` Michal Hocko
2021-01-26 9:53 ` David Hildenbrand
2021-01-26 10:19 ` Michal Hocko
2021-01-26 9:20 ` Michal Hocko
2021-02-03 12:15 ` Michal Hocko
2021-02-04 11:34 ` Mike Rapoport
2021-01-21 12:27 ` [PATCH v16 07/11] secretmem: use PMD-size pages to amortize direct map fragmentation Mike Rapoport
2021-01-26 11:46 ` Michal Hocko
2021-01-26 11:56 ` David Hildenbrand
2021-01-26 12:08 ` Michal Hocko
2021-01-28 9:22 ` Mike Rapoport
2021-01-28 13:01 ` Michal Hocko
2021-01-28 13:28 ` Christoph Lameter
2021-01-28 13:49 ` Michal Hocko
2021-01-28 15:56 ` Christoph Lameter
2021-01-28 16:23 ` Michal Hocko
2021-01-28 15:28 ` James Bottomley
2021-01-29 7:03 ` Mike Rapoport
2021-01-28 21:05 ` James Bottomley
2021-01-29 7:53 ` Michal Hocko
2021-01-29 8:23 ` Michal Hocko
2021-02-01 16:56 ` James Bottomley
2021-02-02 9:35 ` Michal Hocko
2021-02-02 12:48 ` Mike Rapoport
2021-02-02 13:14 ` David Hildenbrand
2021-02-02 13:32 ` Michal Hocko
2021-02-02 14:12 ` David Hildenbrand
2021-02-02 14:22 ` Michal Hocko
2021-02-02 14:26 ` David Hildenbrand
2021-02-02 14:32 ` Michal Hocko
2021-02-02 14:34 ` David Hildenbrand
2021-02-02 18:15 ` Mike Rapoport
2021-02-02 18:55 ` James Bottomley
2021-02-03 12:09 ` Michal Hocko
2021-02-04 11:31 ` Mike Rapoport
2021-02-02 13:27 ` Michal Hocko
2021-02-02 19:10 ` Mike Rapoport
2021-02-03 9:12 ` Michal Hocko
2021-02-04 9:58 ` Mike Rapoport
2021-02-04 13:02 ` Michal Hocko
2021-01-29 7:21 ` Mike Rapoport
2021-01-29 8:51 ` Michal Hocko
2021-02-02 14:42 ` David Hildenbrand
2021-01-21 12:27 ` [PATCH v16 08/11] secretmem: add memcg accounting Mike Rapoport
2021-01-25 16:17 ` Matthew Wilcox
2021-01-25 17:18 ` Shakeel Butt
2021-01-25 21:35 ` Mike Rapoport
2021-01-28 15:07 ` Shakeel Butt
2021-01-25 16:54 ` Michal Hocko
2021-01-25 21:38 ` Mike Rapoport
2021-01-26 7:31 ` Michal Hocko
2021-01-26 8:56 ` Mike Rapoport
2021-01-26 9:15 ` Michal Hocko [this message]
2021-01-26 14:48 ` Matthew Wilcox
2021-01-26 15:05 ` Michal Hocko
2021-01-27 18:42 ` Roman Gushchin
2021-01-28 7:58 ` Michal Hocko
2021-01-28 14:05 ` Shakeel Butt
2021-01-28 14:22 ` Michal Hocko
2021-01-28 14:57 ` Shakeel Butt
2021-01-21 12:27 ` [PATCH v16 09/11] PM: hibernate: disable when there are active secretmem users Mike Rapoport
2021-01-21 12:27 ` [PATCH v16 10/11] arch, mm: wire up memfd_secret system call where relevant Mike Rapoport
2021-01-25 18:18 ` Catalin Marinas
2021-01-21 12:27 ` [PATCH v16 11/11] secretmem: test: add basic selftest for memfd_secret(2) Mike Rapoport
2021-01-21 22:18 ` [PATCH v16 00/11] mm: introduce memfd_secret system call to create "secret" memory areas Andrew Morton
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