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From: Mike Rapoport <rppt@kernel.org>
To: Matthew Wilcox <willy@infradead.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>,
	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>,
	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>
Subject: Re: [PATCH v8 4/9] mm: introduce memfd_secret system call to create "secret" memory areas
Date: Sun, 15 Nov 2020 10:45:39 +0200
Message-ID: <20201115084539.GU4758@kernel.org> (raw)
In-Reply-To: <20201113140656.GG17076@casper.infradead.org>

On Fri, Nov 13, 2020 at 02:06:56PM +0000, Matthew Wilcox wrote:
> On Tue, Nov 10, 2020 at 05:14:39PM +0200, Mike Rapoport wrote:
> > diff --git a/mm/Kconfig b/mm/Kconfig
> > index c89c5444924b..d8d170fa5210 100644
> > --- a/mm/Kconfig
> > +++ b/mm/Kconfig
> > @@ -884,4 +884,7 @@ config ARCH_HAS_HUGEPD
> >  config MAPPING_DIRTY_HELPERS
> >          bool
> >  
> > +config SECRETMEM
> > +	def_bool ARCH_HAS_SET_DIRECT_MAP && !EMBEDDED
> 
> So I now have to build this in, whether I want it or not?

Why wouldn't anybody want this nice feature? ;-)

Now, seriously, I hesitated a lot about having a prompt here, but in the
end I've decided to go without it.

The added footprint is not so big, with x86 defconfig it's less than 8K
and with distro (I've checked with Fedora) config the difference is less
than 1k because they anyway have CMA=y.

As this is "security" feature, disros most probably would have this
enabled anyway, and I believe users that will see something like "Allow
hiding memory from the kernel" will hit Y there.

-- 
Sincerely yours,
Mike.

  reply index

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-10 15:14 [PATCH v8 0/9] " Mike Rapoport
2020-11-10 15:14 ` [PATCH v8 1/9] mm: add definition of PMD_PAGE_ORDER Mike Rapoport
2020-11-10 15:14 ` [PATCH v8 2/9] mmap: make mlock_future_check() global Mike Rapoport
2020-11-10 17:17   ` David Hildenbrand
2020-11-10 18:06     ` Mike Rapoport
2020-11-12 16:22       ` David Hildenbrand
2020-11-12 19:08         ` Mike Rapoport
2020-11-12 20:15           ` David Hildenbrand
2020-11-15  8:26             ` Mike Rapoport
2020-11-17 15:09               ` David Hildenbrand
2020-11-17 15:58                 ` Mike Rapoport
2020-11-10 15:14 ` [PATCH v8 3/9] set_memory: allow set_direct_map_*_noflush() for multiple pages Mike Rapoport
2020-11-13 12:26   ` Catalin Marinas
2020-11-10 15:14 ` [PATCH v8 4/9] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
2020-11-13 13:58   ` Matthew Wilcox
2020-11-15  8:53     ` Mike Rapoport
2020-11-13 14:06   ` Matthew Wilcox
2020-11-15  8:45     ` Mike Rapoport [this message]
2020-11-10 15:14 ` [PATCH v8 5/9] secretmem: use PMD-size pages to amortize direct map fragmentation Mike Rapoport
2020-11-10 15:14 ` [PATCH v8 6/9] secretmem: add memcg accounting Mike Rapoport
2020-11-13  1:35   ` Andrew Morton
2020-11-13 23:42   ` Roman Gushchin
2020-11-15  9:17     ` Mike Rapoport
2020-11-10 15:14 ` [PATCH v8 7/9] PM: hibernate: disable when there are active secretmem users Mike Rapoport
2020-11-10 15:14 ` [PATCH v8 8/9] arch, mm: wire up memfd_secret system call were relevant Mike Rapoport
2020-11-13 12:25   ` Catalin Marinas
2020-11-15  8:56     ` Mike Rapoport
2020-11-10 15:14 ` [PATCH v8 9/9] secretmem: test: add basic selftest for memfd_secret(2) Mike Rapoport
2020-11-12 14:56 ` [PATCH v8 0/9] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport

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