The madv_populate selftest currently builds with a warning when the
local installed headers (via the distribution) don't include
MADV_POPULATE_READ and MADV_POPULATE_WRITE. The warning is correct,
because the test cannot locate the necessary header.
The reason is that the in-tree installed headers (usr/include) have a
"linux" instead of a "sys" subdirectory.
Including "linux/mman.h" instead of "sys/mman.h" doesn't work (e.g.,
mmap() and madvise() are not defined that way). The only thing that
seems to work is including "linux/mman.h" in addition to "sys/mman.h".
We can get rid of our availability check and simplify.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Reported-by: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
When executing transhuge-stress with an argument to specify the virtual
memory size for testing, the ram size is reported as 0, e.g.
transhuge-stress 384
thp-mmap: allocate 192 transhuge pages, using 384 MiB virtual memory and 0 MiB of ram
thp-mmap: 0.184 s/loop, 0.957 ms/page, 2090.265 MiB/s 192 succeed, 0 failed
This appears to be due to a thinko in commit 0085d61fe0
("selftests/vm/transhuge-stress: stress test for memory compaction"),
where, at a guess, the intent was to base "xyz MiB of ram" on `ram`
size.
Here are results after using `ram` size:
thp-mmap: allocate 192 transhuge pages, using 384 MiB virtual memory and 14 MiB of ram
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 0085d61fe0 ("selftests/vm/transhuge-stress: stress test for memory compaction")
Signed-off-by: George G. Davis <[email protected]>
Cc: Konstantin Khlebnikov <[email protected]>
Cc: Eugeniu Rosca <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Today, we assert that the ioctls the kernel reports as supported for a
registration match a precomputed list. We decide which ioctls are
supported by examining the memory type. Then, in several locations we
"fix up" this list by adding or removing things this initial decision
got wrong.
What ioctls the kernel reports is actually a function of several things:
- The memory type
- Kernel feature support (e.g., no writeprotect on aarch64)
- The registration type (e.g., CONTINUE only supported for MINOR mode)
So, we can't fully compute this at the start, in set_test_type. It
varies per test, depending on what registration mode(s) those tests use.
Instead, introduce a new function which computes the correct list. This
centralizes the add/remove of ioctls depending on these function inputs
in one place, so we don't have to repeat ourselves in various tests.
Not only is the resulting code a bit shorter, but it fixes a real bug in
the existing code: previously, we would incorrectly require the
writeprotect ioctl to be present on aarch64, where it isn't actually
supported.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Axel Rasmussen <[email protected]>
Reviewed-by: Peter Xu <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Before any tests are run, in set_test_type, we decide what feature(s) we
are going to be testing, based upon our command line arguments.
However, the supported features are not just a function of the memory
type being used, so this is broken.
For instance, consider writeprotect support. It is "normally" supported
for anonymous memory, but furthermore it requires that the kernel has
CONFIG_HAVE_ARCH_USERFAULTFD_WP. So, it is *not* supported at all on
aarch64, for example.
So, this fixes this by querying the kernel for the set of features it
supports in set_test_type, by opening a userfaultfd and issuing a
UFFDIO_API ioctl. Based upon the reported features, we toggle what
tests are enabled.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Axel Rasmussen <[email protected]>
Reviewed-by: Peter Xu <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Patch series "Small userfaultfd selftest fixups", v2.
This patch (of 3):
Two arguments for doing this:
First, and maybe most importantly, the resulting code is significantly
shorter / simpler.
Then, we avoid using GNU libc extensions. Why does this matter? It
makes testing userfaultfd with the selftest easier e.g. on distros
which use something other than glibc (e.g., Alpine, which uses musl);
basically, it makes the test more portable.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Axel Rasmussen <[email protected]>
Reviewed-by: Peter Xu <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
In RHEL's gating selftests we've encountered memory corruption in the
uffd event test even with upstream kernel:
# ./userfaultfd anon 128 4
nr_pages: 32768, nr_pages_per_cpu: 32768
bounces: 3, mode: rnd racing read, userfaults: 6240 missing (6240) 14729 wp (14729)
bounces: 2, mode: racing read, userfaults: 1444 missing (1444) 28877 wp (28877)
bounces: 1, mode: rnd read, userfaults: 6055 missing (6055) 14699 wp (14699)
bounces: 0, mode: read, userfaults: 82 missing (82) 25196 wp (25196)
testing uffd-wp with pagemap (pgsize=4096): done
testing uffd-wp with pagemap (pgsize=2097152): done
testing events (fork, remap, remove): ERROR: nr 32427 memory corruption 0 1 (errno=0, line=963)
ERROR: faulting process failed (errno=0, line=1117)
It can be easily reproduced when global thp enabled, which is the
default for RHEL.
It's also known as a side effect of commit 0db282ba2c ("selftest: use
mmap instead of posix_memalign to allocate memory", 2021-07-23), which
is imho right itself on using mmap() to make sure the addresses will be
untagged even on arm.
The problem is, for each test we allocate buffers using two
allocate_area() calls. We assumed these two buffers won't affect each
other, however they could, because mmap() could have found that the two
buffers are near each other and having the same VMA flags, so they got
merged into one VMA.
It won't be a big problem if thp is not enabled, but when thp is
agressively enabled it means when initializing the src buffer it could
accidentally setup part of the dest buffer too when there's a shared THP
that overlaps the two regions. Then some of the dest buffer won't be
able to be trapped by userfaultfd missing mode, then it'll cause memory
corruption as described.
To fix it, do release_pages() after initializing the src buffer.
Since the previous two release_pages() calls are after
uffd_test_ctx_clear() which will unmap all the buffers anyway (which is
stronger than release pages; as unmap() also tear town pgtables), drop
them as they shouldn't really be anything useful.
We can mark the Fixes tag upon 0db282ba2c as it's reported to only
happen there, however the real "Fixes" IMHO should be 8ba6e86408, as
before that commit we'll always do explicit release_pages() before
registration of uffd, and 8ba6e86408 changed that logic by adding
extra unmap/map and we didn't release the pages at the right place.
Meanwhile I don't have a solid glue anyway on whether posix_memalign()
could always avoid triggering this bug, hence it's safer to attach this
fix to commit 8ba6e86408.
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 8ba6e86408 ("userfaultfd/selftests: reinitialize test context in each test")
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1994931
Signed-off-by: Peter Xu <[email protected]>
Reported-by: Li Wang <[email protected]>
Tested-by: Li Wang <[email protected]>
Reviewed-by: Axel Rasmussen <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Nadav Amit <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Since merged pages are copied every time they need to be modified, the
write access time is different between shared and non-shared pages. Add
ksm_cow_time() function which evaluates latency of these COW breaks.
First, 4000 pages are allocated and the time, required to modify 1 byte in
every other page, is measured. After this, the pages are merged into 2000
pairs and in each pair, 1 page is modified (i.e. they are decoupled) to
detect COW breaks. The time needed to break COW of merged pages is then
compared with performance of non-shared pages.
The test is run as follows: ./ksm_tests -C
The output:
Total size: 15 MiB
Not merged pages:
Total time: 0.002185489 s
Average speed: 3202.945 MiB/s
Merged pages:
Total time: 0.004386872 s
Average speed: 1595.670 MiB/s
Link: https://lkml.kernel.org/r/1d03ee0d1b341959d4b61672c6401d498bff5652.1629386192.git.zhansayabagdaulet@gmail.com
Signed-off-by: Zhansaya Bagdauletkyzy <[email protected]>
Reviewed-by: Tyler Hicks <[email protected]>
Reviewed-by: Pavel Tatashin <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Patch series "add KSM performance tests", v3.
Extend KSM self tests with a performance benchmark. These tests are not
part of regular regression testing, as they are mainly intended to be used
by developers making changes to the memory management subsystem.
This patch (of 2):
Add ksm_merge_time() function to determine speed and time needed for
merging. The total spent time is shown in seconds while speed is in
MiB/s. User must specify the size of duplicated memory area (in MiB)
before running the test.
The test is run as follows: ./ksm_tests -P -s 100
The output:
Total size: 100 MiB
Total time: 0.201106786 s
Average speed: 497.248 MiB/s
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/318b946ac80cc9205c89d0962048378f7ce0705b.1629386192.git.zhansayabagdaulet@gmail.com
Signed-off-by: Zhansaya Bagdauletkyzy <[email protected]>
Reviewed-by: Tyler Hicks <[email protected]>
Reviewed-by: Pavel Tatashin <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Add check_ksm_numa_merge() function to test that pages in different NUMA
nodes are being handled properly. First, two duplicate pages are
allocated in two separate NUMA nodes using the libnuma library. Since
there is one unique page in each node, with merge_across_nodes = 0, there
won't be any shared pages. If merge_across_nodes is set to 1, the pages
will be treated as usual duplicate pages and will be merged. If NUMA
config is not enabled or the number of NUMA nodes is less than two, then
the test is skipped. The test is run as follows: ./ksm_tests -N
Link: https://lkml.kernel.org/r/071c17b5b04ebb0dfeba137acc495e5dd9d2a719.1626252248.git.zhansayabagdaulet@gmail.com
Signed-off-by: Zhansaya Bagdauletkyzy <[email protected]>
Reviewed-by: Pavel Tatashin <[email protected]>
Reviewed-by: Tyler Hicks <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Patch series "add KSM selftests".
Introduce selftests to validate the functionality of KSM. The tests are
run on private anonymous pages. Since some KSM tunables are modified,
their starting values are saved and restored after testing. At the start,
run is set to 2 to ensure that only test pages will be merged (we assume
that no applications make madvise syscalls in the background). If KSM
config not enabled, all tests will be skipped.
This patch (of 4):
Add check_ksm_merge() function to check the basic merging feature of KSM.
First, some number of identical pages are allocated and the MADV_MERGEABLE
advice is given to merge these pages. Then, pages_shared and
pages_sharing values are compared with the expected numbers using
assert_ksm_pages_count() function. The number of pages can be changed
using -p option.
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/90287685c13300972ea84de93d1f3f900373f9fe.1626252248.git.zhansayabagdaulet@gmail.com
Signed-off-by: Zhansaya Bagdauletkyzy <[email protected]>
Reviewed-by: Pavel Tatashin <[email protected]>
Reviewed-by: Tyler Hicks <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Hugh Dickins <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
When userfaultfd copy-ioctl fails since the PTE already exists, an -EEXIST
error is returned and the faulting thread is not woken. The current
userfaultfd test does not wake the faulting thread in such case. The
assumption is presumably that another thread set the PTE through copy/wp
ioctl and would wake the faulting thread or that alternatively the fault
handler would realize there is no need to "must_wait" and continue. This
is not necessarily true.
There is an assumption that the "must_wait" tests in handle_userfault()
are sufficient to provide definitive answer whether the offending PTE is
populated or not. However, userfaultfd_must_wait() test is lockless.
Consequently, concurrent calls to ptep_modify_prot_start(), for instance,
can clear the PTE and can cause userfaultfd_must_wait() to wrongly assume
it is not populated and a wait is needed.
There are therefore 3 options:
(1) Change the tests to wake on copy failure.
(2) Wake faulting thread unconditionally on zero/copy ioctls before
returning -EEXIST.
(3) Change the userfaultfd_must_wait() to hold locks.
This patch took the first approach, but the others are valid solutions
with different tradeoffs.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Nadav Amit <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Peter Xu <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Axel Rasmussen <[email protected]>
Cc: Mike Rapoport <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
There are several test cases in the vm directory are still using exit 0
when they need to be skipped. Use the kselftest framework to skip code
instead so it can help us to distinguish the return status.
Criterion to filter out what should be fixed in vm directory:
grep -r "exit 0" -B1 | grep -i skip
This change might cause some false-positives if people are running these
test scripts directly and only checking their return codes, which will
change from 0 to 4. However I think the impact should be small as most of
our scripts here are already using this skip code. And there will be no
such issue if running them with the kselftest framework.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Po-Hsu Lin <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
On x86, there is a set of instructions used to save and restore register
state collectively known as the XSAVE architecture. There are about a
dozen different features managed with XSAVE. The protection keys
register, PKRU, is one of those features.
The hardware optimizes XSAVE by tracking when the state has not changed
from its initial (init) state. In this case, it can avoid the cost of
writing state to memory (it would usually just be a bunch of 0's).
When the pkey register is 0x0 the hardware optionally choose to track the
register as being in the init state (optimize away the writes). AMD CPUs
do this more aggressively compared to Intel.
On x86, PKRU is rarely in its (very permissive) init state. Instead, the
value defaults to something very restrictive. It is not surprising that
bugs have popped up in the rare cases when PKRU reaches its init state.
Add a protection key selftest which gets the protection keys register into
its init state in a way that should work on Intel and AMD. Then, do a
bunch of pkey register reads to watch for inadvertent changes.
This adds "-mxsave" to CFLAGS for all the x86 vm selftests in order to
allow use of the XSAVE instruction __builtin functions. This will make
the builtins available on all of the vm selftests, but is expected to be
harmless.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Dave Hansen <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Aneesh Kumar K.V <[email protected]>
Cc: Ram Pai <[email protected]>
Cc: Sandipan Das <[email protected]>
Cc: Florian Weimer <[email protected]>
Cc: "Desnes A. Nunes do Rosario" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Thiago Jung Bauermann <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Michal Suchanek <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
The pkey test code keeps a "shadow" of the pkey register around. This
ensures that any bugs which might write to the register can be caught more
quickly.
Generally, userspace has a good idea when the kernel is going to write to
the register. For instance, alloc_pkey() is passed a permission mask.
The caller of alloc_pkey() can update the shadow based on the return value
and the mask.
But, the kernel can also modify the pkey register in a more sneaky way.
For mprotect(PROT_EXEC) mappings, the kernel will allocate a pkey and
write the pkey register to create an execute-only mapping. The kernel
never tells userspace what key it uses for this.
This can cause the test to fail with messages like:
protection_keys_64.2: pkey-helpers.h:132: _read_pkey_reg: Assertion `pkey_reg == shadow_pkey_reg' failed.
because the shadow was not updated with the new kernel-set value.
Forcibly update the shadow value immediately after an mprotect().
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 6af17cf89e ("x86/pkeys/selftests: Add PROT_EXEC test")
Signed-off-by: Dave Hansen <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Aneesh Kumar K.V <[email protected]>
Cc: Ram Pai <[email protected]>
Cc: Sandipan Das <[email protected]>
Cc: Florian Weimer <[email protected]>
Cc: "Desnes A. Nunes do Rosario" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Thiago Jung Bauermann <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Michal Suchanek <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Patch series "selftests/vm/pkeys: Bug fixes and a new test".
There has been a lot of activity on the x86 front around the XSAVE
architecture which is used to context-switch processor state (among other
things). In addition, AMD has recently joined the protection keys club by
adding processor support for PKU.
The AMD implementation helped uncover a kernel bug around the PKRU "init
state", which actually applied to Intel's implementation but was just
harder to hit. This series adds a test which is expected to help find
this class of bug both on AMD and Intel. All the work around pkeys on x86
also uncovered a few bugs in the selftest.
This patch (of 4):
The "random" pkey allocation code currently does the good old:
srand((unsigned int)time(NULL));
*But*, it unfortunately does this on every random pkey allocation.
There may be thousands of these a second. time() has a one second
resolution. So, each time alloc_random_pkey() is called, the PRNG is
*RESET* to time(). This is nasty. Normally, if you do:
srand(<ANYTHING>);
foo = rand();
bar = rand();
You'll be quite guaranteed that 'foo' and 'bar' are different. But, if
you do:
srand(1);
foo = rand();
srand(1);
bar = rand();
You are quite guaranteed that 'foo' and 'bar' are the *SAME*. The recent
"fix" effectively forced the test case to use the same "random" pkey for
the whole test, unless the test run crossed a second boundary.
Only run srand() once at program startup.
This explains some very odd and persistent test failures I've been seeing.
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 6e373263ce ("selftests/vm/pkeys: fix alloc_random_pkey() to make it really random")
Signed-off-by: Dave Hansen <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Aneesh Kumar K.V <[email protected]>
Cc: Ram Pai <[email protected]>
Cc: Sandipan Das <[email protected]>
Cc: Florian Weimer <[email protected]>
Cc: "Desnes A. Nunes do Rosario" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Thiago Jung Bauermann <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Michal Suchanek <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Currently, the context (fds, mmap-ed areas, etc.) are global. Each test
mutates this state in some way, in some cases really "clobbering it"
(e.g., the events test mremap-ing area_dst over the top of area_src, or
the minor faults tests overwriting the count_verify values in the test
areas). We run the tests in a particular order, each test is careful to
make the right assumptions about its starting state, etc.
But, this is fragile. It's better for a test's success or failure to not
depend on what some other prior test case did to the global state.
To that end, clear and reinitialize the test context at the start of each
test case, so whatever prior test cases did doesn't affect future tests.
This is particularly relevant to this series because the events test's
mremap of area_dst screws up assumptions the minor fault test was relying
on. This wasn't a problem for hugetlb, as we don't mremap in that case.
[[email protected]: fix conflict between this patch and the uffd pagemap series]
Link: https://lkml.kernel.org/r/YKQqKrl+/cQ1utrb@t490s
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Axel Rasmussen <[email protected]>
Signed-off-by: Peter Xu <[email protected]>
Reviewed-by: Peter Xu <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Brian Geffon <[email protected]>
Cc: "Dr . David Alan Gilbert" <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Lokesh Gidra <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Upton <[email protected]>
Cc: Shaohua Li <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Wang Qing <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This is a preparatory commit. In the future, we want to be able to setup
alias mappings for area_src and area_dst in the shmem test, like we do in
the hugetlb_shared test. With a VMA obtained via mmap(MAP_ANONYMOUS |
MAP_SHARED), it isn't clear how to do this.
So, mmap() with an fd, so we can create alias mappings. Use memfd_create
instead of actually passing in a tmpfs path like hugetlb does, since it's
more convenient / simpler to run, and works just as well.
Future commits will:
1. Setup the alias mappings.
2. Extend our tests to actually take advantage of this, to test new
userfaultfd behavior being introduced in this series.
Also, a small fix in the area we're changing: when the hugetlb setup fails
in main(), pass in the right argv[] so we actually print out the hugetlb
file path.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Axel Rasmussen <[email protected]>
Reviewed-by: Peter Xu <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Brian Geffon <[email protected]>
Cc: "Dr . David Alan Gilbert" <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Lokesh Gidra <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Upton <[email protected]>
Cc: Shaohua Li <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Wang Qing <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Patch series "userfaultfd/selftests: A few cleanups", v2.
I wanted to cleanup userfaultfd.c fault handling for a long time. If it's
not cleaned, when the new code grows the file it'll also grow the size
that needs to be cleaned... This is my attempt to cleanup the userfaultfd
selftest on fault handling, to use an err() macro instead of either
fprintf() or perror() then another exit() call.
The huge cleanup is done in the last patch. The first 4 patches are some
other standalone cleanups for the same file, so I put them together.
This patch (of 5):
Userfaultfd selftest does not need to handle kernel initiated fault. Set
user mode so it can be run even if unprivileged_userfaultfd=0 (which is
the default).
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peter Xu <[email protected]>
Reviewed-by: Axel Rasmussen <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Brian Geffon <[email protected]>
Cc: "Dr . David Alan Gilbert" <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Lokesh Gidra <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Upton <[email protected]>
Cc: Shaohua Li <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Wang Qing <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Patch series "mm/gup: Fix pin page write cache bouncing on has_pinned", v2.
This series contains 3 patches, the 1st one enables threading for
gup_benchmark in the kselftest. The latter two patches are collected from
Andrea's local branch which can fix write cache bouncing issue with
pinning fast-gup.
To be explicit on the latter two patches:
- the 2nd patch fixes the perf degrade when introducing has_pinned, then
- the last patch tries to remove the has_pinned with a bit in mm->flags
For patch 3: originally I think we had a plan to reuse has_pinned into a
counter very soon, however that's not happening at least until today, so
maybe it proves that we can remove it until we really want such a counter
for whatever reason. As the commit message stated, it saves 4 bytes for
each mm without observable regressions.
Regarding testing: we can reference to the commit message of patch 2 for
some detailed testing with will-is-scale. Meanwhile I did patch 1 just
because then we can even easily verify the patchset using the existing
kselftest facilities or even regress test it in the future with the repo
if we want.
Below numbers are extra verification tests that I did besides commit
message of patch 2 using the new gup_benchmark and 256 cpus. Below test
is done on 40 cpus host with Intel(R) Xeon(R) CPU E5-2630 v4 @ 2.20GHz,
and I can get similar result (of course the write cache bouncing get
severe with even more cores).
After patch 1 applied (only test patch, so using old kernel):
$ sudo chrt -f 1 ./gup_test -a -m 512 -j 40
PIN_FAST_BENCHMARK: Time: get:459632 put:5990 us
PIN_FAST_BENCHMARK: Time: get:461967 put:5840 us
PIN_FAST_BENCHMARK: Time: get:464521 put:6140 us
PIN_FAST_BENCHMARK: Time: get:465176 put:7100 us
PIN_FAST_BENCHMARK: Time: get:465960 put:6733 us
PIN_FAST_BENCHMARK: Time: get:465324 put:6781 us
PIN_FAST_BENCHMARK: Time: get:466018 put:7130 us
PIN_FAST_BENCHMARK: Time: get:466362 put:7118 us
PIN_FAST_BENCHMARK: Time: get:465118 put:6975 us
PIN_FAST_BENCHMARK: Time: get:466422 put:6602 us
PIN_FAST_BENCHMARK: Time: get:465791 put:6818 us
PIN_FAST_BENCHMARK: Time: get:467091 put:6298 us
PIN_FAST_BENCHMARK: Time: get:467694 put:5432 us
PIN_FAST_BENCHMARK: Time: get:469575 put:5581 us
PIN_FAST_BENCHMARK: Time: get:468124 put:6055 us
PIN_FAST_BENCHMARK: Time: get:468877 put:6720 us
PIN_FAST_BENCHMARK: Time: get:467212 put:4961 us
PIN_FAST_BENCHMARK: Time: get:467834 put:6697 us
PIN_FAST_BENCHMARK: Time: get:470778 put:6398 us
PIN_FAST_BENCHMARK: Time: get:469788 put:6310 us
PIN_FAST_BENCHMARK: Time: get:488277 put:7113 us
PIN_FAST_BENCHMARK: Time: get:486613 put:7085 us
PIN_FAST_BENCHMARK: Time: get:486940 put:7202 us
PIN_FAST_BENCHMARK: Time: get:488728 put:7101 us
PIN_FAST_BENCHMARK: Time: get:487570 put:7327 us
PIN_FAST_BENCHMARK: Time: get:489260 put:7027 us
PIN_FAST_BENCHMARK: Time: get:488846 put:6866 us
PIN_FAST_BENCHMARK: Time: get:488521 put:6745 us
PIN_FAST_BENCHMARK: Time: get:489950 put:6459 us
PIN_FAST_BENCHMARK: Time: get:489777 put:6617 us
PIN_FAST_BENCHMARK: Time: get:488224 put:6591 us
PIN_FAST_BENCHMARK: Time: get:488644 put:6477 us
PIN_FAST_BENCHMARK: Time: get:488754 put:6711 us
PIN_FAST_BENCHMARK: Time: get:488875 put:6743 us
PIN_FAST_BENCHMARK: Time: get:489290 put:6657 us
PIN_FAST_BENCHMARK: Time: get:490264 put:6684 us
PIN_FAST_BENCHMARK: Time: get:489631 put:6737 us
PIN_FAST_BENCHMARK: Time: get:488434 put:6655 us
PIN_FAST_BENCHMARK: Time: get:492213 put:6297 us
PIN_FAST_BENCHMARK: Time: get:491124 put:6173 us
After the whole series applied (new fixed kernel):
$ sudo chrt -f 1 ./gup_test -a -m 512 -j 40
PIN_FAST_BENCHMARK: Time: get:82038 put:7041 us
PIN_FAST_BENCHMARK: Time: get:82144 put:6817 us
PIN_FAST_BENCHMARK: Time: get:83417 put:6674 us
PIN_FAST_BENCHMARK: Time: get:82540 put:6594 us
PIN_FAST_BENCHMARK: Time: get:83214 put:6681 us
PIN_FAST_BENCHMARK: Time: get:83444 put:6889 us
PIN_FAST_BENCHMARK: Time: get:83194 put:7499 us
PIN_FAST_BENCHMARK: Time: get:84876 put:7369 us
PIN_FAST_BENCHMARK: Time: get:86092 put:10289 us
PIN_FAST_BENCHMARK: Time: get:86153 put:10415 us
PIN_FAST_BENCHMARK: Time: get:85026 put:7751 us
PIN_FAST_BENCHMARK: Time: get:85458 put:7944 us
PIN_FAST_BENCHMARK: Time: get:85735 put:8154 us
PIN_FAST_BENCHMARK: Time: get:85851 put:8299 us
PIN_FAST_BENCHMARK: Time: get:86323 put:9617 us
PIN_FAST_BENCHMARK: Time: get:86288 put:10496 us
PIN_FAST_BENCHMARK: Time: get:87697 put:9346 us
PIN_FAST_BENCHMARK: Time: get:87980 put:8382 us
PIN_FAST_BENCHMARK: Time: get:88719 put:8400 us
PIN_FAST_BENCHMARK: Time: get:87616 put:8588 us
PIN_FAST_BENCHMARK: Time: get:86730 put:9563 us
PIN_FAST_BENCHMARK: Time: get:88167 put:8673 us
PIN_FAST_BENCHMARK: Time: get:86844 put:9777 us
PIN_FAST_BENCHMARK: Time: get:88068 put:11774 us
PIN_FAST_BENCHMARK: Time: get:86170 put:15676 us
PIN_FAST_BENCHMARK: Time: get:87967 put:12827 us
PIN_FAST_BENCHMARK: Time: get:95773 put:7652 us
PIN_FAST_BENCHMARK: Time: get:87734 put:13650 us
PIN_FAST_BENCHMARK: Time: get:89833 put:14237 us
PIN_FAST_BENCHMARK: Time: get:96186 put:8029 us
PIN_FAST_BENCHMARK: Time: get:95532 put:8886 us
PIN_FAST_BENCHMARK: Time: get:95351 put:5826 us
PIN_FAST_BENCHMARK: Time: get:96401 put:8407 us
PIN_FAST_BENCHMARK: Time: get:96473 put:8287 us
PIN_FAST_BENCHMARK: Time: get:97177 put:8430 us
PIN_FAST_BENCHMARK: Time: get:98120 put:5263 us
PIN_FAST_BENCHMARK: Time: get:96271 put:7757 us
PIN_FAST_BENCHMARK: Time: get:99628 put:10467 us
PIN_FAST_BENCHMARK: Time: get:99344 put:10045 us
PIN_FAST_BENCHMARK: Time: get:94212 put:15485 us
Summary:
Old kernel: 477729.97 (+-3.79%)
New kernel: 89144.65 (+-11.76%)
This patch (of 3):
Add a new parameter "-j N" to support concurrent gup test.
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peter Xu <[email protected]>
Reviewed-by: John Hubbard <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Kirill Tkhai <[email protected]>
Cc: Kirill Shutemov <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Jann Horn <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Hugh Dickins <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
When pages are pinned they can be faulted in userland and migrated, and
they can be faulted right in kernel without migration.
In either case, the pinned pages must end-up being pinnable (not
movable).
Add a new test to gup_test, to help verify that the gup/pup
(get_user_pages() / pin_user_pages()) behavior with respect to pinnable
and movable pages is reasonable and correct. Specifically, provide a
way to:
1) Verify that only "pinnable" pages are pinned. This is checked
automatically for you.
2) Verify that gup/pup performance is reasonable. This requires
comparing benchmarks between doing gup/pup on pages that have been
pre-faulted in from user space, vs. doing gup/pup on pages that are
not faulted in until gup/pup time (via FOLL_TOUCH). This decision is
controlled with the new -z command line option.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Pavel Tatashin <[email protected]>
Reviewed-by: John Hubbard <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Ira Weiny <[email protected]>
Cc: James Morris <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Sasha Levin <[email protected]>
Cc: Steven Rostedt (VMware) <[email protected]>
Cc: Tyler Hicks <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
In gup_test both gup_flags and test_flags use the same flags field.
This is broken.
Farther, in the actual gup_test.c all the passed gup_flags are erased
and unconditionally replaced with FOLL_WRITE.
Which means that test_flags are ignored, and code like this always
performs pin dump test:
155 if (gup->flags & GUP_TEST_FLAG_DUMP_PAGES_USE_PIN)
156 nr = pin_user_pages(addr, nr, gup->flags,
157 pages + i, NULL);
158 else
159 nr = get_user_pages(addr, nr, gup->flags,
160 pages + i, NULL);
161 break;
Add a new test_flags field, to allow raw gup_flags to work. Add a new
subcommand for DUMP_USER_PAGES_TEST to specify that pin test should be
performed.
Remove unconditional overwriting of gup_flags via FOLL_WRITE. But,
preserve the previous behaviour where FOLL_WRITE was the default flag,
and add a new option "-W" to unset FOLL_WRITE.
Rename flags with gup_flags.
With the fix, dump works like this:
root@virtme:/# gup_test -c
---- page #0, starting from user virt addr: 0x7f8acb9e4000
page:00000000d3d2ee27 refcount:2 mapcount:1 mapping:0000000000000000
index:0x0 pfn:0x100bcf
anon flags: 0x300000000080016(referenced|uptodate|lru|swapbacked)
raw: 0300000000080016 ffffd0e204021608 ffffd0e208df2e88 ffff8ea04243ec61
raw: 0000000000000000 0000000000000000 0000000200000000 0000000000000000
page dumped because: gup_test: dump_pages() test
DUMP_USER_PAGES_TEST: done
root@virtme:/# gup_test -c -p
---- page #0, starting from user virt addr: 0x7fd19701b000
page:00000000baed3c7d refcount:1025 mapcount:1 mapping:0000000000000000
index:0x0 pfn:0x108008
anon flags: 0x300000000080014(uptodate|lru|swapbacked)
raw: 0300000000080014 ffffd0e204200188 ffffd0e205e09088 ffff8ea04243ee71
raw: 0000000000000000 0000000000000000 0000040100000000 0000000000000000
page dumped because: gup_test: dump_pages() test
DUMP_USER_PAGES_TEST: done
Refcount shows the difference between pin vs no-pin case.
Also change type of nr from int to long, as it counts number of pages.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Pavel Tatashin <[email protected]>
Reviewed-by: John Hubbard <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Ira Weiny <[email protected]>
Cc: James Morris <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Sasha Levin <[email protected]>
Cc: Steven Rostedt (VMware) <[email protected]>
Cc: Tyler Hicks <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Fix a dormant bug in userfaultfd_events_test(), where we did `return
faulting_process(0)` instead of `exit(faulting_process(0))`. This
caused the forked process to keep running, trying to execute any further
test cases after the events test in parallel with the "real" process.
Add a simple test case which exercises minor faults. In short, it does
the following:
1. "Sets up" an area (area_dst) and a second shared mapping to the same
underlying pages (area_dst_alias).
2. Register one of these areas with userfaultfd, in minor fault mode.
3. Start a second thread to handle any minor faults.
4. Populate the underlying pages with the non-UFFD-registered side of
the mapping. Basically, memset() each page with some arbitrary
contents.
5. Then, using the UFFD-registered mapping, read all of the page
contents, asserting that the contents match expectations (we expect
the minor fault handling thread can modify the page contents before
resolving the fault).
The minor fault handling thread, upon receiving an event, flips all the
bits (~) in that page, just to prove that it can modify it in some
arbitrary way. Then it issues a UFFDIO_CONTINUE ioctl, to setup the
mapping and resolve the fault. The reading thread should wake up and
see this modification.
Currently the minor fault test is only enabled in hugetlb_shared mode,
as this is the only configuration the kernel feature supports.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Axel Rasmussen <[email protected]>
Reviewed-by: Peter Xu <[email protected]>
Cc: Adam Ruprecht <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Alexey Dobriyan <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Cannon Matthews <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Chinwen Chang <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: "Dr . David Alan Gilbert" <[email protected]>
Cc: Huang Ying <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jann Horn <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Lokesh Gidra <[email protected]>
Cc: "Matthew Wilcox (Oracle)" <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: "Michal Koutn" <[email protected]>
Cc: Michel Lespinasse <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Oliver Upton <[email protected]>
Cc: Shaohua Li <[email protected]>
Cc: Shawn Anastasio <[email protected]>
Cc: Steven Price <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
We did not have a direct user interface of splitting the compound page
backing a THP and there is no need unless we want to expose the THP
implementation details to users. Make <debugfs>/split_huge_pages accept a
new command to do that.
By writing "<pid>,<vaddr_start>,<vaddr_end>" to
<debugfs>/split_huge_pages, THPs within the given virtual address range
from the process with the given pid are split. It is used to test
split_huge_page function. In addition, a selftest program is added to
tools/testing/selftests/vm to utilize the interface by splitting
PMD THPs and PTE-mapped THPs.
This does not change the old behavior, i.e., writing 1 to the interface
to split all THPs in the system.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Zi Yan <[email protected]>
Reviewed-by: Yang Shi <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: "Kirill A . Shutemov" <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Mika Penttila <[email protected]>
Cc: Sandipan Das <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
A 'single_cpu_test' parameter is odd and it does not exist anymore.
Instead there was introduced a 'nr_threads' one. If it is not set it
behaves as the former parameter.
That is why update a "stress mode" according to this change specifying
number of workers which are equal to number of CPUs. Also update an
output of help message based on a new interface.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Uladzislau Rezki (Sony) <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Hillf Danton <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Oleksiy Avramchenko <[email protected]>
Cc: Steven Rostedt <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
David Hildenbrand