diff options
author | David Hildenbrand <david@redhat.com> | 2022-11-16 11:26:40 +0100 |
---|---|---|
committer | Andrew Morton <akpm@linux-foundation.org> | 2022-11-30 15:58:56 -0800 |
commit | 7aca5ca154930a06612f4d7b81f710f3e1027e04 (patch) | |
tree | 42ac18cbde919f9cb72d2c7bc649ed6991f3d6d1 /tools/testing/selftests/vm/Makefile | |
parent | 749477244b05be0d9b6dcc10c161bfa4c4749d78 (diff) |
selftests/vm: anon_cow: prepare for non-anonymous COW tests
Patch series "mm/gup: remove FOLL_FORCE usage from drivers (reliable R/O
long-term pinning)".
For now, we did not support reliable R/O long-term pinning in COW
mappings. That means, if we would trigger R/O long-term pinning in
MAP_PRIVATE mapping, we could end up pinning the (R/O-mapped) shared
zeropage or a pagecache page.
The next write access would trigger a write fault and replace the pinned
page by an exclusive anonymous page in the process page table; whatever
the process would write to that private page copy would not be visible by
the owner of the previous page pin: for example, RDMA could read stale
data. The end result is essentially an unexpected and hard-to-debug
memory corruption.
Some drivers tried working around that limitation by using
"FOLL_FORCE|FOLL_WRITE|FOLL_LONGTERM" for R/O long-term pinning for now.
FOLL_WRITE would trigger a write fault, if required, and break COW before
pinning the page. FOLL_FORCE is required because the VMA might lack write
permissions, and drivers wanted to make that working as well, just like
one would expect (no write access, but still triggering a write access to
break COW).
However, that is not a practical solution, because
(1) Drivers that don't stick to that undocumented and debatable pattern
would still run into that issue. For example, VFIO only uses
FOLL_LONGTERM for R/O long-term pinning.
(2) Using FOLL_WRITE just to work around a COW mapping + page pinning
limitation is unintuitive. FOLL_WRITE would, for example, mark the
page softdirty or trigger uffd-wp, even though, there actually isn't
going to be any write access.
(3) The purpose of FOLL_FORCE is debug access, not access without lack of
VMA permissions by arbitrarty drivers.
So instead, make R/O long-term pinning work as expected, by breaking COW
in a COW mapping early, such that we can remove any FOLL_FORCE usage from
drivers and make FOLL_FORCE ptrace-specific (renaming it to FOLL_PTRACE).
More details in patch #8.
This patch (of 19):
Originally, the plan was to have a separate tests for testing COW of
non-anonymous (e.g., shared zeropage) pages.
Turns out, that we'd need a lot of similar functionality and that there
isn't a really good reason to separate it. So let's prepare for non-anon
tests by renaming to "cow".
Link: https://lkml.kernel.org/r/20221116102659.70287-1-david@redhat.com
Link: https://lkml.kernel.org/r/20221116102659.70287-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andy Walls <awalls@md.metrocast.net>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bernard Metzler <bmt@zurich.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Benvenuti <benve@cisco.com>
Cc: Christian Gmeiner <christian.gmeiner@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Airlie <airlied@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Inki Dae <inki.dae@samsung.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Morris <jmorris@namei.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kentaro Takeda <takedakn@nttdata.co.jp>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nelson Escobar <neescoba@cisco.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oded Gabbay <ogabbay@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux+etnaviv@armlinux.org.uk>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Seung-Woo Kim <sw0312.kim@samsung.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tomasz Figa <tfiga@chromium.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'tools/testing/selftests/vm/Makefile')
-rw-r--r-- | tools/testing/selftests/vm/Makefile | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile index 00920cb8b499..a4d764efd6e3 100644 --- a/tools/testing/selftests/vm/Makefile +++ b/tools/testing/selftests/vm/Makefile @@ -27,7 +27,7 @@ MAKEFLAGS += --no-builtin-rules CFLAGS = -Wall -I $(top_srcdir) -I $(top_srcdir)/usr/include $(EXTRA_CFLAGS) $(KHDR_INCLUDES) LDLIBS = -lrt -lpthread -TEST_GEN_FILES = anon_cow +TEST_GEN_FILES = cow TEST_GEN_FILES += compaction_test TEST_GEN_FILES += gup_test TEST_GEN_FILES += hmm-tests @@ -98,7 +98,7 @@ TEST_FILES += va_128TBswitch.sh include ../lib.mk -$(OUTPUT)/anon_cow: vm_util.c +$(OUTPUT)/cow: vm_util.c $(OUTPUT)/khugepaged: vm_util.c $(OUTPUT)/madv_populate: vm_util.c $(OUTPUT)/soft-dirty: vm_util.c @@ -154,8 +154,8 @@ warn_32bit_failure: endif endif -# ANON_COW_EXTRA_LIBS may get set in local_config.mk, or it may be left empty. -$(OUTPUT)/anon_cow: LDLIBS += $(ANON_COW_EXTRA_LIBS) +# cow_EXTRA_LIBS may get set in local_config.mk, or it may be left empty. +$(OUTPUT)/cow: LDLIBS += $(COW_EXTRA_LIBS) $(OUTPUT)/mlock-random-test $(OUTPUT)/memfd_secret: LDLIBS += -lcap @@ -168,7 +168,7 @@ local_config.mk local_config.h: check_config.sh EXTRA_CLEAN += local_config.mk local_config.h -ifeq ($(ANON_COW_EXTRA_LIBS),) +ifeq ($(COW_EXTRA_LIBS),) all: warn_missing_liburing warn_missing_liburing: |