| Age | Commit message (Collapse) | Author |
|---|
|
Rename selftets/vm to selftests/mm for being more consistent with the
code, documentation, and tools directories, and won't be confused with
virtual machines.
[sj@kernel.org: convert missing vm->mm changes]
Link: https://lkml.kernel.org/r/20230107230643.252273-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20230103180754.129637-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
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>
|
|
io_uring provides a simple mechanism to test long-term, R/W GUP pins
-- via fixed buffers -- and can be used to verify that GUP pins stay
in sync with the pages in the page table even if a page would
temporarily get mapped R/O or concurrent fork() could accidentially
end up sharing pinned pages with the child.
Note that this essentially re-introduces local_config support that was
removed recently in commit 6f83d6c74ea5 ("Kselftests: remove support of
libhugetlbfs from kselftests").
[david@redhat.com: s/size_t/ssize_t/ on `cur', `total'.]
Link: https://lkml.kernel.org/r/445fe1ae-9e22-0d1d-4d09-272231d2f84a@redhat.com
Link: https://lkml.kernel.org/r/20220927110120.106906-6-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Christoph von Recklinghausen <crecklin@redhat.com>
Cc: Don Dutile <ddutile@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
libhugetlbfs, the user side utitlity to work with hugepages, does not have
any active support. There are only 2 selftests which are part of in
vm/hmm_test.c that depends on libhugetlbfs.
This patch modifies the tests so that they will not require libhugetlb
library.
[axelrasmussen@google.com: : remove orphaned references to local_config.{h,mk}]
Link: https://lkml.kernel.org/r/20220831211526.2743216-1-axelrasmussen@google.com
Link: https://lkml.kernel.org/r/20220801070231.13831-1-tsahu@linux.ibm.com
Signed-off-by: Tarun Sahu <tsahu@linux.ibm.com>
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Tested-by: Zach O'Keefe <zokeefe@google.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Shivaprasad G Bhat <sbhat@linux.ibm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vaibhav Jain <vaibhav@linux.ibm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
HMM selftests are incredibly useful, but they are only effective if people
actually build and run them. All the other tests in selftests/vm can be
built with very standard, always-available libraries: libpthread, librt.
The hmm-tests.c program, on the other hand, requires something that is
(much) less readily available: libhugetlbfs. And so the build will
typically fail for many developers.
A simple attempt to install libhugetlbfs will also run into complications
on some common distros these days: Fedora and Arch Linux (yes, Arch AUR
has it, but that's fragile, as always with AUR). The library is not
maintained actively enough at the moment, for distros to deal with it. I
had to build it from source, for Fedora, and that didn't go too smoothly
either.
It turns out that, out of 21 tests in hmm-tests.c, only 2 actually require
functionality from libhugetlbfs. Therefore, if libhugetlbfs is missing,
simply ifdef those two tests out and allow the developer to at least have
the other 19 tests, if they don't want to pause to work through the above
issues. Also issue a warning, so that it's clear that there is an
imperfection in the build.
In order to do that, a tiny shell script (check_config.sh) runs a quick
compile (not link, that's too prone to false failures with library paths),
and basically, if the compiler doesn't find hugetlbfs.h in its standard
locations, then the script concludes that libhugetlbfs is not available.
The output is in two files, one for inclusion in hmm-test.c
(local_config.h), and one for inclusion in the Makefile (local_config.mk).
Link: https://lkml.kernel.org/r/20201026064021.3545418-9-jhubbard@nvidia.com
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
