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From: Joerg Roedel <joro@8bytes.org>
To: x86@kernel.org
Cc: hpa@zytor.com, Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	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>, Joerg Roedel <jroedel@suse.de>,
	joro@8bytes.org, linux-kernel@vger.kernel.org,
	linux-acpi@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-mm@kvack.org
Subject: [RFC PATCH 0/7] mm: Get rid of vmalloc_sync_(un)mappings()
Date: Fri,  8 May 2020 16:40:36 +0200
Message-ID: <20200508144043.13893-1-joro@8bytes.org> (raw)

Hi,

after the recent issue with vmalloc and tracing code[1] on x86 and a
long history of previous issues related to the vmalloc_sync_mappings()
interface, I thought the time has come to remove it. Please
see [2], [3], and [4] for some other issues in the past.

The patches are based on v5.7-rc4 and add tracking of page-table
directory changes to the vmalloc and ioremap code. Depending on which
page-table levels changes have been made, a new per-arch function is
called: arch_sync_kernel_mappings().

On x86-64 with 4-level paging, this function will not be called more
than 64 times in a systems runtime (because vmalloc-space takes 64 PGD
entries which are only populated, but never cleared).

As a side effect this also allows to get rid of vmalloc faults on x86,
making it safe to touch vmalloc'ed memory in the page-fault handler.
Note that this potentially includes per-cpu memory.

The code is tested on x86-64, x86-32 with and without PAE. It also fixes
the issue described in [1]. Additionally this code has been
compile-tested on almost all architectures supported by Linux. I
couldn't find working compilers for hexagon and unicore32, so these are
not tested.

Please review.

Regards,

	Joerg

[1] https://lore.kernel.org/lkml/20200430141120.GA8135@suse.de/
[2] https://lore.kernel.org/lkml/20191009124418.8286-1-joro@8bytes.org/
[3] https://lore.kernel.org/lkml/20190719184652.11391-1-joro@8bytes.org/
[4] https://lore.kernel.org/lkml/20191126111119.GA110513@gmail.com/

Joerg Roedel (7):
  mm: Add functions to track page directory modifications
  mm/vmalloc: Track which page-table levels were modified
  mm/ioremap: Track which page-table levels were modified
  x86/mm/64: Implement arch_sync_kernel_mappings()
  x86/mm/32: Implement arch_sync_kernel_mappings()
  mm: Remove vmalloc_sync_(un)mappings()
  x86/mm: Remove vmalloc faulting

 arch/x86/include/asm/pgtable-2level_types.h |   2 +
 arch/x86/include/asm/pgtable-3level_types.h |   2 +
 arch/x86/include/asm/pgtable_64_types.h     |   2 +
 arch/x86/include/asm/switch_to.h            |  23 ---
 arch/x86/kernel/setup_percpu.c              |   6 +-
 arch/x86/mm/fault.c                         | 176 +-------------------
 arch/x86/mm/init_64.c                       |   5 +
 arch/x86/mm/pti.c                           |   8 +-
 drivers/acpi/apei/ghes.c                    |   6 -
 include/asm-generic/5level-fixup.h          |   5 +-
 include/asm-generic/pgtable.h               |  23 +++
 include/linux/mm.h                          |  46 +++++
 include/linux/vmalloc.h                     |  13 +-
 kernel/notifier.c                           |   1 -
 lib/ioremap.c                               |  46 +++--
 mm/nommu.c                                  |  12 --
 mm/vmalloc.c                                | 109 +++++++-----
 17 files changed, 199 insertions(+), 286 deletions(-)

-- 
2.17.1


             reply index

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-08 14:40 Joerg Roedel [this message]
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
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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