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Date: Tue, 6 Dec 2022 15:47:04 +0100
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Hugh Dickins <hughd@...gle.com>,
John Hubbard <jhubbard@...dia.com>,
Jason Gunthorpe <jgg@...dia.com>,
Mike Rapoport <rppt@...ux.ibm.com>,
Yang Shi <shy828301@...il.com>,
Vlastimil Babka <vbabka@...e.cz>,
Nadav Amit <namit@...are.com>,
Andrea Arcangeli <aarcange@...hat.com>,
Peter Xu <peterx@...hat.com>, linux-mm@...ck.org,
x86@...nel.org, linux-alpha@...r.kernel.org,
linux-snps-arc@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org, linux-csky@...r.kernel.org,
linux-hexagon@...r.kernel.org, linux-ia64@...r.kernel.org,
loongarch@...ts.linux.dev, linux-m68k@...ts.linux-m68k.org,
linux-mips@...r.kernel.org, openrisc@...ts.librecores.org,
linux-parisc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
linux-sh@...r.kernel.org, sparclinux@...r.kernel.org,
linux-um@...ts.infradead.org, linux-xtensa@...ux-xtensa.org,
David Hildenbrand <david@...hat.com>,
Albert Ou <aou@...s.berkeley.edu>,
Anton Ivanov <anton.ivanov@...bridgegreys.com>,
Borislav Petkov <bp@...en8.de>, Brian Cain <bcain@...cinc.com>,
Christophe Leroy <christophe.leroy@...roup.eu>,
Chris Zankel <chris@...kel.net>,
Dave Hansen <dave.hansen@...ux.intel.com>,
"David S. Miller" <davem@...emloft.net>,
Dinh Nguyen <dinguyen@...nel.org>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Greg Ungerer <gerg@...ux-m68k.org>,
Guo Ren <guoren@...nel.org>, Helge Deller <deller@....de>,
"H. Peter Anvin" <hpa@...or.com>,
Huacai Chen <chenhuacai@...nel.org>,
Ingo Molnar <mingo@...hat.com>,
Ivan Kokshaysky <ink@...assic.park.msu.ru>,
"James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
Johannes Berg <johannes@...solutions.net>,
Matt Turner <mattst88@...il.com>,
Max Filippov <jcmvbkbc@...il.com>,
Michael Ellerman <mpe@...erman.id.au>,
Michal Simek <monstr@...str.eu>,
Nicholas Piggin <npiggin@...il.com>,
Palmer Dabbelt <palmer@...belt.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Richard Henderson <richard.henderson@...aro.org>,
Richard Weinberger <richard@....at>,
Rich Felker <dalias@...c.org>,
Russell King <linux@...linux.org.uk>,
Stafford Horne <shorne@...il.com>,
Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
Thomas Gleixner <tglx@...utronix.de>,
Vineet Gupta <vgupta@...nel.org>,
WANG Xuerui <kernel@...0n.name>,
Yoshinori Sato <ysato@...rs.sourceforge.jp>
Subject: [PATCH mm-unstable RFC 00/26] mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on all architectures with swap PTEs
This is the follow-up on [1]:
[PATCH v2 0/8] mm: COW fixes part 3: reliable GUP R/W FOLL_GET of
anonymous pages
After we implemented __HAVE_ARCH_PTE_SWP_EXCLUSIVE on most prominent
enterprise architectures, implement __HAVE_ARCH_PTE_SWP_EXCLUSIVE on all
remaining architectures that support swap PTEs.
This makes sure that exclusive anonymous pages will stay exclusive, even
after they were swapped out -- for example, making GUP R/W FOLL_GET of
anonymous pages reliable. Details can be found in [1].
This primarily fixes remaining known O_DIRECT memory corruptions that can
happen on concurrent swapout, whereby we can lose DMA reads to a page
(modifying the user page by writing to it).
To verify, there are two test cases (requiring swap space, obviously):
(1) The O_DIRECT+swapout test case [2] from Andrea. This test case tries
triggering a race condition.
(2) My vmsplice() test case [3] that tries to detect if the exclusive
marker was lost during swapout, not relying on a race condition.
For example, on 32bit x86 (with and without PAE), my test case fails
without these patches:
$ ./test_swp_exclusive
FAIL: page was replaced during COW
But succeeds with these patches:
$ ./test_swp_exclusive
PASS: page was not replaced during COW
Why implement __HAVE_ARCH_PTE_SWP_EXCLUSIVE for all architectures, even
the ones where swap support might be in a questionable state? This is the
first step towards removing "readable_exclusive" migration entries, and
instead using pte_swp_exclusive() also with (readable) migration entries
instead (as suggested by Peter). The only missing piece for that is
supporting pmd_swp_exclusive() on relevant architectures with THP
migration support.
As all relevant architectures now implement __HAVE_ARCH_PTE_SWP_EXCLUSIVE,,
we can drop __HAVE_ARCH_PTE_SWP_EXCLUSIVE in the last patch.
RFC because some of the swap PTE layouts are really tricky and I really
need some feedback related to deciphering these layouts and "using yet
unused PTE bits in swap PTEs". I tried cross-compiling all relevant setups
(phew, I might only miss some power/nohash variants), but only tested on
x86 so far.
CCing arch maintainers only on this cover letter and on the respective
patch(es).
[1] https://lkml.kernel.org/r/20220329164329.208407-1-david@redhat.com
[2] https://gitlab.com/aarcange/kernel-testcases-for-v5.11/-/blob/main/page_count_do_wp_page-swap.c
[3] https://gitlab.com/davidhildenbrand/scratchspace/-/blob/main/test_swp_exclusive.c
David Hildenbrand (26):
mm/debug_vm_pgtable: more pte_swp_exclusive() sanity checks
alpha/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
arc/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
arm/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
csky/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
hexagon/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
ia64/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
loongarch/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
m68k/mm: remove dummy __swp definitions for nommu
m68k/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
microblaze/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
mips/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
nios2/mm: refactor swap PTE layout
nios2/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
openrisc/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
parisc/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
powerpc/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on 32bit book3s
powerpc/nohash/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
riscv/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
sh/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
sparc/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on 32bit
sparc/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on 64bit
um/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
x86/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE also on 32bit
xtensa/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
mm: remove __HAVE_ARCH_PTE_SWP_EXCLUSIVE
arch/alpha/include/asm/pgtable.h | 40 ++++++++-
arch/arc/include/asm/pgtable-bits-arcv2.h | 26 +++++-
arch/arm/include/asm/pgtable-2level.h | 3 +
arch/arm/include/asm/pgtable-3level.h | 3 +
arch/arm/include/asm/pgtable.h | 34 ++++++--
arch/arm64/include/asm/pgtable.h | 1 -
arch/csky/abiv1/inc/abi/pgtable-bits.h | 13 ++-
arch/csky/abiv2/inc/abi/pgtable-bits.h | 19 ++--
arch/csky/include/asm/pgtable.h | 17 ++++
arch/hexagon/include/asm/pgtable.h | 36 ++++++--
arch/ia64/include/asm/pgtable.h | 31 ++++++-
arch/loongarch/include/asm/pgtable-bits.h | 4 +
arch/loongarch/include/asm/pgtable.h | 38 +++++++-
arch/m68k/include/asm/mcf_pgtable.h | 35 +++++++-
arch/m68k/include/asm/motorola_pgtable.h | 37 +++++++-
arch/m68k/include/asm/pgtable_no.h | 6 --
arch/m68k/include/asm/sun3_pgtable.h | 38 +++++++-
arch/microblaze/include/asm/pgtable.h | 44 +++++++---
arch/mips/include/asm/pgtable-32.h | 86 ++++++++++++++++---
arch/mips/include/asm/pgtable-64.h | 23 ++++-
arch/mips/include/asm/pgtable.h | 35 ++++++++
arch/nios2/include/asm/pgtable-bits.h | 3 +
arch/nios2/include/asm/pgtable.h | 37 ++++++--
arch/openrisc/include/asm/pgtable.h | 40 +++++++--
arch/parisc/include/asm/pgtable.h | 40 ++++++++-
arch/powerpc/include/asm/book3s/32/pgtable.h | 37 ++++++--
arch/powerpc/include/asm/book3s/64/pgtable.h | 1 -
arch/powerpc/include/asm/nohash/32/pgtable.h | 22 +++--
arch/powerpc/include/asm/nohash/32/pte-40x.h | 6 +-
arch/powerpc/include/asm/nohash/32/pte-44x.h | 18 +---
arch/powerpc/include/asm/nohash/32/pte-85xx.h | 4 +-
arch/powerpc/include/asm/nohash/64/pgtable.h | 24 +++++-
arch/powerpc/include/asm/nohash/pgtable.h | 15 ++++
arch/powerpc/include/asm/nohash/pte-e500.h | 1 -
arch/riscv/include/asm/pgtable-bits.h | 3 +
arch/riscv/include/asm/pgtable.h | 28 ++++--
arch/s390/include/asm/pgtable.h | 1 -
arch/sh/include/asm/pgtable_32.h | 53 +++++++++---
arch/sparc/include/asm/pgtable_32.h | 26 +++++-
arch/sparc/include/asm/pgtable_64.h | 37 +++++++-
arch/sparc/include/asm/pgtsrmmu.h | 14 +--
arch/um/include/asm/pgtable.h | 36 +++++++-
arch/x86/include/asm/pgtable-2level.h | 26 ++++--
arch/x86/include/asm/pgtable-3level.h | 26 +++++-
arch/x86/include/asm/pgtable.h | 3 -
arch/xtensa/include/asm/pgtable.h | 31 +++++--
include/linux/pgtable.h | 29 -------
mm/debug_vm_pgtable.c | 25 +++++-
mm/memory.c | 4 -
mm/rmap.c | 11 ---
50 files changed, 943 insertions(+), 227 deletions(-)
--
2.38.1
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