From: Andy Lutomirski <luto@kernel.org>
To: Joerg Roedel <jroedel@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>, Joerg Roedel <joro@8bytes.org>,
X86 ML <x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Arnd Bergmann <arnd@arndb.de>,
Andrew Morton <akpm@linux-foundation.org>,
Steven Rostedt <rostedt@goodmis.org>,
Vlastimil Babka <vbabka@suse.cz>,
Michal Hocko <mhocko@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Linux ACPI <linux-acpi@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>
Subject: Re: [RFC PATCH 0/7] mm: Get rid of vmalloc_sync_(un)mappings()
Date: Fri, 8 May 2020 16:49:17 -0700 [thread overview]
Message-ID: <CALCETrVxP87o2+aaf=RLW--DSpMrs=BXSQphN6bG5Y4X+OY8GQ@mail.gmail.com> (raw)
In-Reply-To: <20200508213609.GU8135@suse.de>
On Fri, May 8, 2020 at 2:36 PM Joerg Roedel <jroedel@suse.de> wrote:
>
> On Fri, May 08, 2020 at 02:33:19PM -0700, Andy Lutomirski wrote:
> > On Fri, May 8, 2020 at 7:40 AM Joerg Roedel <joro@8bytes.org> wrote:
>
> > What's the maximum on other system types? It might make more sense to
> > take the memory hit and pre-populate all the tables at boot so we
> > never have to sync them.
>
> Need to look it up for 5-level paging, with 4-level paging its 64 pages
> to pre-populate the vmalloc area.
>
> But that would not solve the problem on x86-32, which needs to
> synchronize unmappings on the PMD level.
What changes in this series with x86-32? We already do that
synchronization, right? IOW, in the cases where the vmalloc *fault*
code does anything at all, we should have a small bound for how much
memory to preallocate and, if we preallocate it, then there is nothing
to sync and nothing to fault. And we have the benefit that we never
need to sync anything on 64-bit, which is kind of nice.
Do we actually need PMD-level things for 32-bit? What if we just
outlawed huge pages in the vmalloc space on 32-bit non-PAE?
Or maybe the net result isn't much of a cleanup after all given the
need to support 32-bit.
>
>
> Joerg
next prev parent reply other threads:[~2020-05-08 23:49 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-08 14:40 [RFC PATCH 0/7] mm: Get rid of vmalloc_sync_(un)mappings() Joerg Roedel
2020-05-08 14:40 ` [RFC PATCH 1/7] mm: Add functions to track page directory modifications Joerg Roedel
2020-05-08 14:40 ` [RFC PATCH 2/7] mm/vmalloc: Track which page-table levels were modified Joerg Roedel
2020-05-08 19:10 ` Peter Zijlstra
2020-05-08 21:23 ` Joerg Roedel
2020-05-08 14:40 ` [RFC PATCH 3/7] mm/ioremap: " Joerg Roedel
2020-05-08 14:40 ` [RFC PATCH 4/7] x86/mm/64: Implement arch_sync_kernel_mappings() Joerg Roedel
2020-05-08 14:40 ` [RFC PATCH 5/7] x86/mm/32: " Joerg Roedel
2020-05-08 14:40 ` [RFC PATCH 6/7] mm: Remove vmalloc_sync_(un)mappings() Joerg Roedel
2020-05-08 18:58 ` Steven Rostedt
2020-05-08 21:24 ` Joerg Roedel
2020-05-08 14:40 ` [RFC PATCH 7/7] x86/mm: Remove vmalloc faulting Joerg Roedel
2020-05-08 19:20 ` [RFC PATCH 0/7] mm: Get rid of vmalloc_sync_(un)mappings() Peter Zijlstra
2020-05-08 21:34 ` Joerg Roedel
2020-05-09 9:25 ` Peter Zijlstra
2020-05-09 17:54 ` Joerg Roedel
2020-05-10 1:11 ` Matthew Wilcox
2020-05-11 7:31 ` Peter Zijlstra
2020-05-11 15:52 ` Matthew Wilcox
2020-05-11 16:08 ` Matthew Wilcox
2020-05-11 17:02 ` Peter Zijlstra
2020-05-08 21:33 ` Andy Lutomirski
2020-05-08 21:36 ` Joerg Roedel
2020-05-08 23:49 ` Andy Lutomirski [this message]
2020-05-09 17:52 ` Joerg Roedel
2020-05-09 19:05 ` Andy Lutomirski
2020-05-09 21:57 ` Joerg Roedel
2020-05-10 5:05 ` Andy Lutomirski
2020-05-10 8:15 ` Joerg Roedel
2020-05-11 7:42 ` Peter Zijlstra
2020-05-11 15:36 ` Andy Lutomirski
2020-05-11 17:06 ` Peter Zijlstra
2020-05-11 19:14 ` Joerg Roedel
2020-05-11 19:36 ` Andy Lutomirski
2020-05-12 15:02 ` Joerg Roedel
2020-05-12 15:13 ` Steven Rostedt
2020-05-11 20:50 ` Steven Rostedt
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