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When slub_kunit is not built-in, call kfree_rcu() and kfree_rcu_nolock()
to test kfree_rcu_nolock() in slub_kunit.
Rename the test case as the test covers more _nolock() APIs.
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Signed-off-by: Harry Yoo (Oracle) <harry@kernel.org>
Link: https://patch.msgid.link/20260729-kfree_rcu_nolock-v5-8-a28cdcda9673@kernel.org
Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
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Since kmalloc_nolock() always fails in NMI and hardirq contexts on
PREEMPT_RT, slub_kunit cannot properly test _nolock() APIs.
Register a kprobe pre-handler to invoke kmalloc_nolock() and
kfree_nolock() in the middle of the slab allocator. However, do not
register the handler on UP kernels because that use case is not
well supported [1] in the kernel.
To attach the pre-handler while s->cpu_sheaves->lock or n->list_lock
is held, add a wrapper function for lockdep_assert_held() that calls
a no-op function slab_attach_kprobe_locked() on debug builds. The
function is optimized away when neither CONFIG_PROVE_LOCKING nor
CONFIG_DEBUG_VM is selected and register_kprobe() fails.
The function calls barrier() to prevent the compiler from optimizing
away its callsites. Otherwise, the compiler may consider the function
does not have any side effect and remove callsites.
Compared to using plain kprobe, this has two advantages: 1) it avoids
hardcoding function names in the test, and 2) it can trigger those APIs
in the middle of a function, where the lock is expected to be held as
annotated with lockdep.
While it was proposed [2] to use kunit function redirection to test
this, it is currently infeasible as some lock helpers don't have
symbols.
Factor out the nested loop that calls kmalloc and friends to
test_kmalloc_kfree(), and call them in
test_kmalloc_kfree_nolock_{perf,kprobe}(), each being an independent
test case. During the refactoring, drop alloc_fail handling as it
doesn't provide much benefits.
Link: https://lore.kernel.org/linux-mm/20260427-nolock-api-fix-v2-0-a6b83a92d9a4@kernel.org [1]
Link: https://lore.kernel.org/linux-mm/6edebc2b-5f5a-4b9c-9a4c-564310acee1b@kernel.org [2]
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Reviewed-by: Shengming Hu <hu.shengming@zte.com.cn>
Signed-off-by: Harry Yoo (Oracle) <harry@kernel.org>
Link: https://patch.msgid.link/20260729-kfree_rcu_nolock-v5-1-a28cdcda9673@kernel.org
Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
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Testing invocation of {kmalloc,kfree}_nolock() during kmalloc() or
kfree() is tricky, and it is even harder to ensure that slowpaths are
properly tested. Lack of such testing has led to late discovery of
the bug fixed by commit a1e244a9f177 ("mm/slab: use prandom if
!allow_spin").
Add a slub_kunit test that allocates and frees objects in a tight loop
while a perf event triggers interrupts (NMI or hardirq depending on
the arch) on the same task, invoking {kmalloc,kfree}_nolock() from the
overflow handler.
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Harry Yoo (Oracle) <harry@kernel.org>
Link: https://patch.msgid.link/20260406090907.11710-3-harry@kernel.org
Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
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Modules without a description now cause a warning:
WARNING: modpost: missing MODULE_DESCRIPTION() in lib/tests/slub_kunit.o
Link: https://lkml.kernel.org/r/20250324173242.1501003-10-arnd@kernel.org
Fixes: 6c6c1fc09de3 ("modpost: require a MODULE_DESCRIPTION()")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Guenetr Roeck <linux@roeck-us.net>
Cc: Jeff Johnson <jeff.johnson@oss.qualcomm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Pei Xiao <xiaopei01@kylinos.cn>
Cc: Rae Moar <rmoar@google.com>
Cc: Stehen Rothwell <sfr@canb.auug.org.au>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab
Pull slab updates from Vlastimil Babka:
- Move the TINY_RCU kvfree_rcu() implementation from RCU to SLAB
subsystem and cleanup its integration (Vlastimil Babka)
Following the move of the TREE_RCU batching kvfree_rcu()
implementation in 6.14, move also the simpler TINY_RCU variant.
Refactor the #ifdef guards so that the simple implementation is also
used with SLUB_TINY.
Remove the need for RCU to recognize fake callback function pointers
(__is_kvfree_rcu_offset()) when handling call_rcu() by implementing a
callback that calculates the object's address from the embedded
rcu_head address without knowing its offset.
- Improve kmalloc cache randomization in kvmalloc (GONG Ruiqi)
Due to an extra layer of function call, all kvmalloc() allocations
used the same set of random caches. Thanks to moving the kvmalloc()
implementation to slub.c, this is improved and randomization now
works for kvmalloc.
- Various improvements to debugging, testing and other cleanups (Hyesoo
Yu, Lilith Gkini, Uladzislau Rezki, Matthew Wilcox, Kevin Brodsky, Ye
Bin)
* tag 'slab-for-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab:
slub: Handle freelist cycle in on_freelist()
mm/slab: call kmalloc_noprof() unconditionally in kmalloc_array_noprof()
slab: Mark large folios for debugging purposes
kunit, slub: Add test_kfree_rcu_wq_destroy use case
mm, slab: cleanup slab_bug() parameters
mm: slub: call WARN() when detecting a slab corruption
mm: slub: Print the broken data before restoring them
slab: Achieve better kmalloc caches randomization in kvmalloc
slab: Adjust placement of __kvmalloc_node_noprof
mm/slab: simplify SLAB_* flag handling
slab: don't batch kvfree_rcu() with SLUB_TINY
rcu, slab: use a regular callback function for kvfree_rcu
rcu: remove trace_rcu_kvfree_callback
slab, rcu: move TINY_RCU variant of kvfree_rcu() to SLAB
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Following from the recent KUnit file naming discussion[1], move all
KUnit tests in lib/ into lib/tests/.
Link: https://lore.kernel.org/lkml/20240720165441.it.320-kees@kernel.org/ [1]
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: David Gow <davidgow@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Rae Moar <rmoar@google.com>
Link: https://lore.kernel.org/r/20241202075545.3648096-4-davidgow@google.com
Signed-off-by: Kees Cook <kees@kernel.org>
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