From: Peter Zijlstra <peterz@infradead.org>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Dan Williams <dan.j.williams@intel.com>,
Mike Rapoport <rppt@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Alexey Dobriyan <adobriyan@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
James Bottomley <jejb@linux.ibm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Linux API <linux-api@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
the arch/x86 maintainers <x86@kernel.org>,
Mike Rapoport <rppt@linux.ibm.com>
Subject: Re: [PATCH RFC] mm: add MAP_EXCLUSIVE to create exclusive user mappings
Date: Tue, 29 Oct 2019 09:56:02 +0100 [thread overview]
Message-ID: <20191029085602.GI4114@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20191029064318.s4n4gidlfjun3d47@box>
On Tue, Oct 29, 2019 at 09:43:18AM +0300, Kirill A. Shutemov wrote:
> But some CPUs don't like to have two TLB entries for the same memory with
> different sizes at the same time. See for instance AMD erratum 383.
>
> Getting it right would require making the range not present, flush TLB and
> only then install huge page. That's what we do for userspace.
>
> It will not fly for the direct mapping. There is no reasonable way to
> exclude other CPU from accessing the range while it's not present (call
> stop_machine()? :P). Moreover, the range may contain the code that doing
> the collapse or data required for it...
>
> BTW, looks like current __split_large_page() in pageattr.c is susceptible
> to the errata. Maybe we can get away with the easy way...
As you write above, there is just no way we can have a (temporary) hole
in the direct map.
We are careful about that other errata, and make sure both translations
are identical wrt everything else.
next prev parent reply other threads:[~2019-10-29 8:56 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-27 10:17 [PATCH RFC] mm: add MAP_EXCLUSIVE to create exclusive user mappings Mike Rapoport
2019-10-27 10:17 ` Mike Rapoport
2019-10-28 12:31 ` Kirill A. Shutemov
2019-10-28 13:00 ` Mike Rapoport
2019-10-28 13:16 ` Kirill A. Shutemov
2019-10-28 13:55 ` Peter Zijlstra
2019-10-28 19:59 ` Edgecombe, Rick P
2019-10-28 21:00 ` Peter Zijlstra
2019-10-28 21:00 ` Peter Zijlstra
2019-10-29 17:27 ` Edgecombe, Rick P
2019-10-29 17:27 ` Edgecombe, Rick P
2019-10-30 10:04 ` Peter Zijlstra
2019-10-30 10:04 ` Peter Zijlstra
2019-10-30 15:35 ` Alexei Starovoitov
2019-10-30 15:35 ` Alexei Starovoitov
2019-10-30 18:39 ` Peter Zijlstra
2019-10-30 18:39 ` Peter Zijlstra
2019-10-30 18:52 ` Alexei Starovoitov
2019-10-30 18:52 ` Alexei Starovoitov
2019-10-30 17:48 ` Edgecombe, Rick P
2019-10-30 17:48 ` Edgecombe, Rick P
2019-10-30 17:58 ` Dave Hansen
2019-10-30 17:58 ` Dave Hansen
2019-10-30 18:01 ` Dave Hansen
2019-10-30 18:01 ` Dave Hansen
2019-10-29 5:43 ` Dan Williams
2019-10-29 6:43 ` Kirill A. Shutemov
2019-10-29 8:56 ` Peter Zijlstra [this message]
2019-10-29 11:00 ` Kirill A. Shutemov
2019-10-29 12:39 ` AMD TLB errata, (Was: [PATCH RFC] mm: add MAP_EXCLUSIVE to create exclusive user mappings) Peter Zijlstra
2019-11-15 14:12 ` Tom Lendacky
2019-11-15 14:31 ` Peter Zijlstra
2019-10-29 19:43 ` [PATCH RFC] mm: add MAP_EXCLUSIVE to create exclusive user mappings Dan Williams
2019-10-29 20:07 ` Dave Hansen
2019-10-29 7:08 ` Christopher Lameter
2019-10-29 8:55 ` Mike Rapoport
2019-10-29 10:12 ` Christopher Lameter
2019-10-30 7:11 ` Mike Rapoport
2019-10-30 12:09 ` Christopher Lameter
2019-10-28 14:55 ` David Hildenbrand
2019-10-28 17:12 ` Dave Hansen
2019-10-28 17:32 ` Sean Christopherson
2019-10-28 18:08 ` Matthew Wilcox
2019-10-29 9:28 ` Mike Rapoport
2019-10-29 9:19 ` Mike Rapoport
2019-10-28 18:02 ` Andy Lutomirski
2019-10-29 11:02 ` David Hildenbrand
2019-10-30 8:15 ` Mike Rapoport
2019-10-30 8:19 ` David Hildenbrand
2019-10-31 19:16 ` Mike Rapoport
2019-10-31 21:52 ` Dan Williams
2019-10-29 18:03 ` kbuild test robot
2019-10-27 10:30 ` Florian Weimer
2019-10-27 11:00 ` Mike Rapoport
2019-10-27 11:00 ` Mike Rapoport
2019-10-28 20:23 ` Florian Weimer
2019-10-29 9:01 ` Mike Rapoport
2019-10-28 20:44 ` Andy Lutomirski
2019-10-29 9:32 ` Mike Rapoport
2019-10-29 17:00 ` Andy Lutomirski
2019-10-30 8:40 ` Mike Rapoport
2019-10-30 21:28 ` Andy Lutomirski
2019-10-31 7:21 ` Mike Rapoport
2019-12-05 15:34 ` Mike Rapoport
2019-12-05 15:34 ` Mike Rapoport
2019-12-08 14:10 ` [PATCH] mm: extend memfd with ability to create secret memory kbuild test robot
2019-12-08 14:10 ` kbuild test robot
2019-12-08 14:10 ` kbuild test robot
2019-10-29 11:25 ` [PATCH RFC] mm: add MAP_EXCLUSIVE to create exclusive user mappings Reshetova, Elena
2019-10-29 15:13 ` Tycho Andersen
2019-10-29 17:03 ` Andy Lutomirski
2019-10-29 17:03 ` Andy Lutomirski
2019-10-29 17:37 ` Alan Cox
2019-10-29 17:43 ` James Bottomley
2019-10-29 18:10 ` Andy Lutomirski
2019-10-29 18:10 ` Andy Lutomirski
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