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From: Kees Cook <keescook@chromium.org>
To: Suren Baghdasaryan <surenb@google.com>
Cc: "Matthew Wilcox" <willy@infradead.org>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Colin Cross" <ccross@google.com>,
	"Sumit Semwal" <sumit.semwal@linaro.org>,
	"Michal Hocko" <mhocko@suse.com>,
	"Dave Hansen" <dave.hansen@intel.com>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	"Vlastimil Babka" <vbabka@suse.cz>,
	"Johannes Weiner" <hannes@cmpxchg.org>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Al Viro" <viro@zeniv.linux.org.uk>,
	"Randy Dunlap" <rdunlap@infradead.org>,
	"Kalesh Singh" <kaleshsingh@google.com>,
	"Peter Xu" <peterx@redhat.com>,
	rppt@kernel.org, "Peter Zijlstra" <peterz@infradead.org>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	vincenzo.frascino@arm.com,
	"Chinwen Chang (張錦文)" <chinwen.chang@mediatek.com>,
	"Axel Rasmussen" <axelrasmussen@google.com>,
	"Andrea Arcangeli" <aarcange@redhat.com>,
	"Jann Horn" <jannh@google.com>,
	apopple@nvidia.com, "John Hubbard" <jhubbard@nvidia.com>,
	"Yu Zhao" <yuzhao@google.com>, "Will Deacon" <will@kernel.org>,
	fenghua.yu@intel.com, thunder.leizhen@huawei.com,
	"Hugh Dickins" <hughd@google.com>,
	feng.tang@intel.com, "Jason Gunthorpe" <jgg@ziepe.ca>,
	"Roman Gushchin" <guro@fb.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	krisman@collabora.com, chris.hyser@oracle.com,
	"Peter Collingbourne" <pcc@google.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	"Jens Axboe" <axboe@kernel.dk>,
	legion@kernel.org, "Rolf Eike Beer" <eb@emlix.com>,
	"Cyrill Gorcunov" <gorcunov@gmail.com>,
	"Muchun Song" <songmuchun@bytedance.com>,
	"Viresh Kumar" <viresh.kumar@linaro.org>,
	"Thomas Cedeno" <thomascedeno@google.com>,
	sashal@kernel.org, cxfcosmos@gmail.com,
	"Rasmus Villemoes" <linux@rasmusvillemoes.dk>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-mm <linux-mm@kvack.org>,
	kernel-team <kernel-team@android.com>
Subject: Re: [PATCH v9 2/3] mm: add a field to store names for private anonymous memory
Date: Thu, 30 Sep 2021 16:25:02 -0700	[thread overview]
Message-ID: <202109301621.3E03AE14F@keescook> (raw)
In-Reply-To: <CAJuCfpH8LtKG+1LpVb8JM73dL11yaqR7io8+HDHLGNUVZYVTQw@mail.gmail.com>

On Thu, Sep 30, 2021 at 11:56:12AM -0700, Suren Baghdasaryan wrote:
> I thought more about these alternative suggestions for userspace to
> record allocations but that would introduce considerable complexity
> into userspace. Userspace would have to collect and consolidate this
> data by some daemon, all users would have to query it for the data
> (IPC or something similar), in case this daemon crashes the data would
> need to be somehow recovered. So, in short, it's possible but makes
> things much more complex compared to proposed in-kernel
> implementation.

Agreed: this is something for the kernel to manage.

> OTOH, the only downside of the current implementation is the
> additional memory required to store anon vma names. I checked the
> memory consumption on the latest Android with these patches and
> because we share vma names during fork, the actual memory required to
> store vma names is no more than 600kB. Even on older phones like Pixel
> 3 with 4GB RAM, this is less than 0.015% of total memory. IMHO, this
> is an acceptable price to pay.

I think that's entirely fine. We don't end up with any GUP games, and
everything is refcounted.

I think a v10 with the various nits fixed would be a good next step
here. What do you think Matthew?

-- 
Kees Cook

  reply	other threads:[~2021-09-30 23:25 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-02 23:18 [PATCH v9 1/3] mm: rearrange madvise code to allow for reuse Suren Baghdasaryan
2021-09-02 23:18 ` Suren Baghdasaryan
2021-09-02 23:18 ` [PATCH v9 2/3] mm: add a field to store names for private anonymous memory Suren Baghdasaryan
2021-09-02 23:18   ` Suren Baghdasaryan
2021-09-03 21:35   ` Kees Cook
2021-09-03 21:51     ` Suren Baghdasaryan
2021-09-05 13:04     ` Pavel Machek
2021-09-06 15:52       ` Suren Baghdasaryan
2021-09-03 21:47   ` Kees Cook
2021-09-03 21:56     ` Suren Baghdasaryan
2021-09-03 22:28       ` Kees Cook
2021-10-01  3:44         ` Suren Baghdasaryan
2021-10-01  5:19           ` Kees Cook
2021-09-06 16:55   ` Matthew Wilcox
2021-09-09  4:05     ` Suren Baghdasaryan
2021-09-30 18:56       ` Suren Baghdasaryan
2021-09-30 23:25         ` Kees Cook [this message]
2021-10-01  7:01   ` Rasmus Villemoes
2021-10-01 16:34     ` Suren Baghdasaryan
2021-09-02 23:18 ` [PATCH v9 3/3] mm: add anonymous vma name refcounting Suren Baghdasaryan
2021-09-02 23:18   ` Suren Baghdasaryan
2021-09-03 22:20   ` Kees Cook
2021-09-03  0:28 ` [PATCH v9 1/3] mm: rearrange madvise code to allow for reuse Suren Baghdasaryan

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