From: Mike Rapoport <rppt@kernel.org>
To: David Hildenbrand <david@redhat.com>
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>,
Dave Hansen <dave.hansen@linux.intel.com>,
Elena Reshetova <elena.reshetova@intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Hagen Paul Pfeifer <hagen@jauu.net>,
Ingo Molnar <mingo@redhat.com>,
James Bottomley <jejb@linux.ibm.com>,
Kees Cook <keescook@chromium.org>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Matthew Wilcox <willy@infradead.org>,
Matthew Garrett <mjg59@srcf.ucam.org>,
Mark Rutland <mark.rutland@arm.com>,
Michal Hocko <mhocko@suse.com>,
Mike Rapoport <rppt@linux.ibm.com>,
Michael Kerrisk <mtk.manpages@gmail.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Palmer Dabbelt <palmerdabbelt@google.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Peter Zijlstra <peterz@infradead.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net >,
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>,
Yury Norov <yury.norov@gmail.com>,
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
Subject: Re: [PATCH v19 5/8] mm: introduce memfd_secret system call to create "secret" memory areas
Date: Mon, 17 May 2021 10:23:09 +0300 [thread overview]
Message-ID: <YKIZ3Zfai00A2O15@kernel.org> (raw)
In-Reply-To: <ea1ddcfa-f52d-9a7d-cb7b-8502b38a90da@redhat.com>
On Fri, May 14, 2021 at 10:50:55AM +0200, David Hildenbrand wrote:
> On 13.05.21 20:47, Mike Rapoport wrote:
> > From: Mike Rapoport <rppt@linux.ibm.com>
> >
> > Removing of the pages from the direct map may cause its fragmentation
> > on architectures that use large pages to map the physical memory
> > which affects the system performance. However, the original Kconfig
> > text for CONFIG_DIRECT_GBPAGES said that gigabyte pages in the direct
> > map "... can improve the kernel's performance a tiny bit ..." (commit
> > 00d1c5e05736 ("x86: add gbpages switches")) and the recent report [1]
> > showed that "... although 1G mappings are a good default choice,
> > there is no compelling evidence that it must be the only choice".
> > Hence, it is sufficient to have secretmem disabled by default with
> > the ability of a system administrator to enable it at boot time.
>
> Maybe add a link to the Intel performance evaluation.
" ... the recent report [1]" and the link below.
> > Pages in the secretmem regions are unevictable and unmovable to
> > avoid accidental exposure of the sensitive data via swap or during
> > page migration.
...
> > A page that was a part of the secret memory area is cleared when it
> > is freed to ensure the data is not exposed to the next user of that
> > page.
>
> You could skip that with init_on_free (and eventually also with
> init_on_alloc) set to avoid double clearing.
Right, but for now I'd prefer to keep this explicit in the secretmem
implementation. We may add the check for init_on_free/init_on_alloc later
on.
> > [1]
> > https://lore.kernel.org/linux-mm/213b4567-46ce-f116-9cdf-bbd0c884eb3c@linux.intel.com/
>
--
Sincerely yours,
Mike.
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next prev parent reply other threads:[~2021-05-17 7:23 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-13 18:47 [PATCH v19 0/8] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
2021-05-13 18:47 ` [PATCH v19 1/8] mmap: make mlock_future_check() global Mike Rapoport
2021-05-14 8:27 ` David Hildenbrand
2021-05-13 18:47 ` [PATCH v19 2/8] riscv/Kconfig: make direct map manipulation options depend on MMU Mike Rapoport
2021-05-14 8:28 ` David Hildenbrand
2021-05-13 18:47 ` [PATCH v19 3/8] set_memory: allow set_direct_map_*_noflush() for multiple pages Mike Rapoport
2021-05-14 8:43 ` David Hildenbrand
2021-05-16 7:13 ` Mike Rapoport
2021-05-13 18:47 ` [PATCH v19 4/8] set_memory: allow querying whether set_direct_map_*() is actually enabled Mike Rapoport
2021-05-13 18:47 ` [PATCH v19 5/8] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
2021-05-14 8:50 ` David Hildenbrand
2021-05-17 7:23 ` Mike Rapoport [this message]
2021-05-14 9:25 ` David Hildenbrand
2021-05-16 7:29 ` Mike Rapoport
2021-05-18 9:59 ` Michal Hocko
2021-05-18 10:06 ` David Hildenbrand
2021-05-18 10:31 ` Michal Hocko
2021-05-18 10:35 ` David Hildenbrand
2021-05-18 11:08 ` Michal Hocko
2021-05-19 7:13 ` Mike Rapoport
2021-05-13 18:47 ` [PATCH v19 6/8] PM: hibernate: disable when there are active secretmem users Mike Rapoport
2021-05-14 9:27 ` David Hildenbrand
2021-05-18 10:24 ` Mark Rutland
2021-05-18 10:27 ` David Hildenbrand
2021-05-19 1:32 ` James Bottomley
2021-05-19 1:49 ` Dan Williams
2021-05-19 3:50 ` James Bottomley
2021-05-13 18:47 ` [PATCH v19 7/8] arch, mm: wire up memfd_secret system call where relevant Mike Rapoport
2021-05-14 9:27 ` David Hildenbrand
2021-05-13 18:47 ` [PATCH v19 8/8] secretmem: test: add basic selftest for memfd_secret(2) Mike Rapoport
2021-05-14 9:40 ` David Hildenbrand
2021-05-13 19:08 ` [PATCH v19 0/8] mm: introduce memfd_secret system call to create "secret" memory areas James Bottomley
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