Re: [PATCH v9 2/3] mm: add a field to store names for private anonymous memory

From: Suren Baghdasaryan <surenb@google.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: "Kees Cook" <keescook@chromium.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>,
	"Matthew Wilcox" <willy@infradead.org>,
	"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: Mon, 6 Sep 2021 08:52:23 -0700	[thread overview]
Message-ID: <CAJuCfpH9o=SPE=vspc-o8mFomyg_LZsx7OQtzSQh91pTwKH6Mg@mail.gmail.com> (raw)
In-Reply-To: <20210905130418.GA7117@localhost>

On Sun, Sep 5, 2021 at 6:04 AM Pavel Machek <pavel@ucw.cz> wrote:
>
> Hi!
>
> > > the process is still running, so it has to have some sort of
> > > synchronization with every layer of userspace.  Efficiently tracking
> > > the ranges requires reimplementing something like the kernel vma
> > > trees, and linking to it from every layer of userspace.  It requires
> > > more memory, more syscalls, more runtime cost, and more complexity to
> > > separately track regions that the kernel is already tracking.
>
> Ok so far.
>
> > > This patch adds a field to /proc/pid/maps and /proc/pid/smaps to show a
> > > userspace-provided name for anonymous vmas.  The names of named anonymous
> > > vmas are shown in /proc/pid/maps and /proc/pid/smaps as [anon:<name>].
> > >
> > > Userspace can set the name for a region of memory by calling
> > > prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, start, len, (unsigned
> > > long)name);
>
> Would setting a 64-bit integer instead of name be enough? Even if
> each party would set it randomly, risk of collisions would be very
> low... and we'd not have to deal with strings in kernel.

Thanks for the question, Pavel. I believe this was discussed in this
thread before and Colin provided the explanation with usage examples:
https://lore.kernel.org/linux-mm/20200821070552.GW2074@grain/.
Thanks,
Suren.

>
>                                                                 Pavel
>
>
> --
>
> --
> To unsubscribe from this group and stop receiving emails from it, send an email to kernel-team+unsubscribe@android.com.
>