Two failure patterns are seen randomly when running slub_kunit tests with
CONFIG_SLAB_FREELIST_RANDOM and CONFIG_SLAB_FREELIST_HARDENED enabled.
Pattern 1:
# test_clobber_zone: pass:1 fail:0 skip:0 total:1
ok 1 test_clobber_zone
# test_next_pointer: EXPECTATION FAILED at lib/slub_kunit.c:72
Expected 3 == slab_errors, but
slab_errors == 0 (0x0)
# test_next_pointer: EXPECTATION FAILED at lib/slub_kunit.c:84
Expected 2 == slab_errors, but
slab_errors == 0 (0x0)
# test_next_pointer: pass:0 fail:1 skip:0 total:1
not ok 2 test_next_pointer
In this case, test_next_pointer() overwrites p[s->offset], but the data
at p[s->offset] is already 0x12.
Pattern 2:
ok 1 test_clobber_zone
# test_next_pointer: EXPECTATION FAILED at lib/slub_kunit.c:72
Expected 3 == slab_errors, but
slab_errors == 2 (0x2)
# test_next_pointer: pass:0 fail:1 skip:0 total:1
not ok 2 test_next_pointer
In this case, p[s->offset] has a value other than 0x12, but one of the
expected failures is nevertheless missing.
Invert data instead of writing a fixed value to corrupt the cache data
structures to fix the problem.
Fixes: 1f9f78b1b3 ("mm/slub, kunit: add a KUnit test for SLUB debugging functionality")
Cc: Oliver Glitta <glittao@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
CC: Daniel Latypov <dlatypov@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
This KUnit next update for Linux 6.2-rc1 consists of several enhancements,
fixes, clean-ups, documentation updates, improvements to logging and KTAP
compliance of KUnit test output:
- log numbers in decimal and hex
- parse KTAP compliant test output
- allow conditionally exposing static symbols to tests
when KUNIT is enabled
- make static symbols visible during kunit testing
- clean-ups to remove unused structure definition
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Merge tag 'linux-kselftest-kunit-next-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest
Pull KUnit updates from Shuah Khan:
"Several enhancements, fixes, clean-ups, documentation updates,
improvements to logging and KTAP compliance of KUnit test output:
- log numbers in decimal and hex
- parse KTAP compliant test output
- allow conditionally exposing static symbols to tests when KUNIT is
enabled
- make static symbols visible during kunit testing
- clean-ups to remove unused structure definition"
* tag 'linux-kselftest-kunit-next-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: (29 commits)
Documentation: dev-tools: Clarify requirements for result description
apparmor: test: make static symbols visible during kunit testing
kunit: add macro to allow conditionally exposing static symbols to tests
kunit: tool: make parser preserve whitespace when printing test log
Documentation: kunit: Fix "How Do I Use This" / "Next Steps" sections
kunit: tool: don't include KTAP headers and the like in the test log
kunit: improve KTAP compliance of KUnit test output
kunit: tool: parse KTAP compliant test output
mm: slub: test: Use the kunit_get_current_test() function
kunit: Use the static key when retrieving the current test
kunit: Provide a static key to check if KUnit is actively running tests
kunit: tool: make --json do nothing if --raw_ouput is set
kunit: tool: tweak error message when no KTAP found
kunit: remove KUNIT_INIT_MEM_ASSERTION macro
Documentation: kunit: Remove redundant 'tips.rst' page
Documentation: KUnit: reword description of assertions
Documentation: KUnit: make usage.rst a superset of tips.rst, remove duplication
kunit: eliminate KUNIT_INIT_*_ASSERT_STRUCT macros
kunit: tool: remove redundant file.close() call in unit test
kunit: tool: unit tests all check parser errors, standardize formatting a bit
...
Use the newly-added function kunit_get_current_test() instead of
accessing current->kunit_test directly. This function uses a static key
to return more quickly when KUnit is enabled, but no tests are actively
running. There should therefore be a negligible performance impact to
enabling the slub KUnit tests.
Other than the performance improvement, this should be a no-op.
Cc: Oliver Glitta <glittao@gmail.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Gow <davidgow@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
kmalloc redzone check for slub has been merged, and it's better to add
a kunit case for it, which is inspired by a real-world case as described
in commit 120ee599b5 ("staging: octeon-usb: prevent memory corruption"):
"
octeon-hcd will crash the kernel when SLOB is used. This usually happens
after the 18-byte control transfer when a device descriptor is read.
The DMA engine is always transferring full 32-bit words and if the
transfer is shorter, some random garbage appears after the buffer.
The problem is not visible with SLUB since it rounds up the allocations
to word boundary, and the extra bytes will go undetected.
"
To avoid interrupting the normal functioning of kmalloc caches, a
kmem_cache mimicing kmalloc cache is created with similar flags, and
kmalloc_trace() is used to really test the orig_size and redzone setup.
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Feng Tang <feng.tang@intel.com>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
When kfence is enabled, the buffer allocated from the test case
could be from a kfence pool, and the operation could be also
caught and reported by kfence first, causing the case to fail.
With default kfence setting, this is very difficult to be triggered.
By changing CONFIG_KFENCE_NUM_OBJECTS from 255 to 16383, and
CONFIG_KFENCE_SAMPLE_INTERVAL from 100 to 5, the allocation from
kfence did hit 7 times in different slub_kunit cases out of 900
times of boot test.
To avoid this, initially we tried is_kfence_address() to check this
and repeated allocation till finding a non-kfence address. Vlastimil
Babka suggested SLAB_SKIP_KFENCE flag could be used to achieve this,
and better add a wrapper function for simplifying cache creation.
Signed-off-by: Feng Tang <feng.tang@intel.com>
Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
slub_kunit does not expect other debugging flags to be set when running
tests. When SLAB_RED_ZONE flag is set globally, test fails because the
flag affects number of errors reported.
To make slub_kunit unaffected by user specified debugging flags,
introduce SLAB_NO_USER_FLAGS to ignore them. With this flag, only flags
specified in the code are used and others are ignored.
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Link: https://lore.kernel.org/r/Yk0sY9yoJhFEXWOg@hyeyoo
SLUB has resiliency_test() function which is hidden behind #ifdef
SLUB_RESILIENCY_TEST that is not part of Kconfig, so nobody runs it.
KUnit should be a proper replacement for it.
Try changing byte in redzone after allocation and changing pointer to next
free node, first byte, 50th byte and redzone byte. Check if validation
finds errors.
There are several differences from the original resiliency test: Tests
create own caches with known state instead of corrupting shared kmalloc
caches.
The corruption of freepointer uses correct offset, the original resiliency
test got broken with freepointer changes.
Scratch changing random byte test, because it does not have meaning in
this form where we need deterministic results.
Add new option CONFIG_SLUB_KUNIT_TEST in Kconfig. Tests next_pointer,
first_word and clobber_50th_byte do not run with KASAN option on. Because
the test deliberately modifies non-allocated objects.
Use kunit_resource to count errors in cache and silence bug reports.
Count error whenever slab_bug() or slab_fix() is called or when the count
of pages is wrong.
[glittao@gmail.com: remove unused function test_exit(), from SLUB KUnit test]
Link: https://lkml.kernel.org/r/20210512140656.12083-1-glittao@gmail.com
[akpm@linux-foundation.org: export kasan_enable/disable_current to modules]
Link: https://lkml.kernel.org/r/20210511150734.3492-2-glittao@gmail.com
Signed-off-by: Oliver Glitta <glittao@gmail.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Daniel Latypov <dlatypov@google.com>
Acked-by: Marco Elver <elver@google.com>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Guenter Roeck