Patch series "mm/ksm: break_ksm() cleanups and fixes", v2.
This series cleans up and fixes break_ksm(). In summary, we no longer use
fake write faults to break COW but instead FAULT_FLAG_UNSHARE. Further,
we move away from using follow_page() --- that we can hopefully remove
completely at one point --- and use new walk_page_range_vma() instead.
Fortunately, we can get rid of VM_FAULT_WRITE and FOLL_MIGRATION in common
code now.
Extend the existing ksm tests by an unmerge benchmark, and a some new
unmerge tests.
Also, add a selftest to measure MADV_UNMERGEABLE performance. In my setup
(AMD Ryzen 9 3900X), running the KSM selftest to test unmerge performance
on 2 GiB (taskset 0x8 ./ksm_tests -D -s 2048), this results in a
performance degradation of ~6% -- 7% (old: ~5250 MiB/s, new: ~4900 MiB/s).
I don't think we particularly care for now, but it's good to be aware of
the implication.
This patch (of 9):
Let's add three unmerge tests (MADV_UNMERGEABLE unmerging all pages in the
range).
test_unmerge(): basic unmerge tests
test_unmerge_discarded(): have some pte_none() entries in the range
test_unmerge_uffd_wp(): protect the merged pages using uffd-wp
ksm_tests.c currently contains a mixture of benchmarks and tests, whereby
each test is carried out by executing the ksm_tests binary with specific
parameters. Let's add new ksm_functional_tests.c that performs multiple,
smaller functional tests all at once.
Link: https://lkml.kernel.org/r/20221021101141.84170-1-david@redhat.com
Link: https://lkml.kernel.org/r/20221021101141.84170-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
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>
Our memory management kernel CI testing at Red Hat uses the VM
selftests and we have run into two problems:
First, our LTP tests overlap with the VM selftests.
We want to avoid unhelpful redundancy in our testing practices.
Second, we have observed the current run_vmtests.sh to report overall
failure/ambiguous results in the case that a machine lacks the necessary
hardware to perform one or more of the tests. E.g. ksm tests that
require more than one numa node.
We want to be able to run the vm selftests suitable to particular hardware.
Add the ability to run one or more groups of vm tests via run_vmtests.sh
instead of simply all-or-none in order to solve these problems.
Preserve existing default behavior of running all tests when the script
is invoked with no arguments.
Documentation of test groups is included in the patch as follows:
# ./run_vmtests.sh [ -h || --help ]
usage: ./tools/testing/selftests/vm/run_vmtests.sh [ -h | -t "<categories>"]
-t: specify specific categories to tests to run
-h: display this message
The default behavior is to run all tests.
Alternatively, specific groups tests can be run by passing a string
to the -t argument containing one or more of the following categories
separated by spaces:
- mmap
tests for mmap(2)
- gup_test
tests for gup using gup_test interface
- userfaultfd
tests for userfaultfd(2)
- compaction
a test for the patch "Allow compaction of unevictable pages"
- mlock
tests for mlock(2)
- mremap
tests for mremap(2)
- hugevm
tests for very large virtual address space
- vmalloc
vmalloc smoke tests
- hmm
hmm smoke tests
- madv_populate
test memadvise(2) MADV_POPULATE_{READ,WRITE} options
- memfd_secret
test memfd_secret(2)
- process_mrelease
test process_mrelease(2)
- ksm
ksm tests that do not require >=2 NUMA nodes
- ksm_numa
ksm tests that require >=2 NUMA nodes
- pkey
memory protection key tests
- soft_dirty
test soft dirty page bit semantics
- anon_cow
test anonymous copy-on-write semantics
example: ./run_vmtests.sh -t "hmm mmap ksm"
Link: https://lkml.kernel.org/r/20221018231222.1884715-1-jsavitz@redhat.com
Signed-off-by: Joel Savitz <jsavitz@redhat.com>
Cc: Joel Savitz <jsavitz@redhat.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "selftests/vm: test COW handling of anonymous memory".
This is my current set of tests for testing COW handling of anonymous
memory, especially when interacting with GUP. I developed these tests
while working on PageAnonExclusive and managed to clean them up just now.
On current upstream Linux, all tests pass except the hugetlb tests that
rely on vmsplice -- these tests should pass as soon as vmsplice properly
uses FOLL_PIN instead of FOLL_GET.
I'm working on additional tests for COW handling in private mappings,
focusing on long-term R/O pinning e.g., of the shared zeropage, pagecache
pages and KSM pages. These tests, however, will go into a different file.
So this is everything I have regarding tests for anonymous memory.
This patch (of 7):
Let's start adding tests for our COW handling of anonymous memory. We'll
focus on basic tests that we can achieve without additional libraries or
gup_test extensions.
We'll add THP and hugetlb tests separately.
[david@redhat.com: s/size_t/ssize_t/ on `cur', `total', `transferred';]
Link: https://lkml.kernel.org/r/51302b9e-dc69-d709-3214-f23868028555@redhat.com
Link: https://lkml.kernel.org/r/20220927110120.106906-1-david@redhat.com
Link: https://lkml.kernel.org/r/20220927110120.106906-2-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>
The test va_128TBswitch.c expects to be able to pass mmap an address hint
and length that cross the address 1<<47. On x86_64, this is not possible
without 5-level page tables, so the test fails.
The test is already only run on 64-bit powerpc and x86_64 archs, but this
patch adds an additional check on x86_64 that skips the test if
PG_TABLE_LEVELS < 5. There is precedent for checking /proc/config.gz in
selftests, e.g. in selftests/firmware.
Running the tests produces the desired output:
sudo make -C tools/testing/selftests TARGETS=vm run_tests
---------------------------
running ./va_128TBswitch.sh
---------------------------
./va_128TBswitch.sh: PG_TABLE_LEVELS=4, must be >= 5 to run this test
[SKIP]
-------------------------------
[adam@wowsignal.io: restrict the check to x86_64]
Link: https://lkml.kernel.org/r/20220628163654.337600-1-adam@wowsignal.io
[adam@wowsignal.io: fix formatting issues, rename "die" to "fail"]
Link: https://lkml.kernel.org/r/20220701163030.415735-1-adam@wowsignal.io
Link: https://lkml.kernel.org/r/20220627163912.5581-1-adam@wowsignal.io
Signed-off-by: Adam Sindelar <adam@wowsignal.io>
Cc: Adam Sindelar <ats@fb.com>
Cc: David Vernet <void@manifault.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Introduce process_mrelease syscall sanity tests which include tests
which expect to fail:
- process_mrelease with invalid pidfd and flags inputs
- process_mrelease on a live process with no pending signals
and valid process_mrelease usage which is expected to succeed. Because
process_mrelease has to be used against a process with a pending SIGKILL,
it's possible that the process exits before process_mrelease gets called.
In such cases we retry the test with a victim that allocates twice more
memory up to 1GB. This would require the victim process to spend more
time during exit and process_mrelease has a better chance of catching the
process before it exits and succeeding.
On success the test reports the amount of memory the child had to allocate
for reaping to succeed. Sample output:
$ mrelease_test
Success reaping a child with 1MB of memory allocations
On failure the test reports the failure. Sample outputs:
$ mrelease_test
All process_mrelease attempts failed!
$ mrelease_test
process_mrelease: Invalid argument
Link: https://lkml.kernel.org/r/20220518204316.13131-1-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
These might not be issues yet, but they make the script more fragile.
Also by fixing them we give a better example to future readers, who might
copy/paste or otherwise re-use snippets from our script.
- Use "read -r", since we don't ever want read to be interpreting '\'
characters as escape sequences...
- Quote variables, to deal with spaces properly.
- Use $() instead of the older and harder-to-nest ``.
- Get rid of superfluous "$" prefixes inside arithmetic $(()).
Link: https://lkml.kernel.org/r/20220421224928.1848230-2-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Previously, each test printed out its own header, dealt with its own
return code, etc. By just putting this standard stuff in a function, we
can delete > 300 lines from the script.
This also makes adding future tests easier. And, it gets rid of various
inconsistencies that already exist:
- Some tests correctly deal with ksft_skip, but others don't.
- Some tests just print the executable name, others print arguments, and
yet others print some comment in the header.
- Most tests print out a header with two separator lines, but not the
HMM smoke test or the memfd_secret test, which only print one.
- We had a redundant "exit" at the end, with all the boilerplate it's an
easy oversight.
Link: https://lkml.kernel.org/r/20220421224928.1848230-1-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The hugetlb vma mremap() test currently maps 1GB of memory to trigger
pmd sharing and make sure that 'unshare' path in mremap code works. The
test originally only mapped 10MB of memory (as specified by the header
comment) but was later modified to 1GB to tackle this case.
However, not all machines will have 1GB of memory to spare for this
test. Adding a mapping size arg will allow run_vmtest.sh to pass an
adequate mapping size, while allowing users to run the test
independently with arbitrary size mappings.
Link: https://lkml.kernel.org/r/20211124203805.3700355-1-yosryahmed@google.com
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
