Instead of popping only the maximum element from the heap during each
iteration, we now pop the two largest elements at once. Although this
introduces an additional comparison to determine the second largest
element, it enables a reduction in the height of the tree by one during
the heapify operations starting from root's left/right child. This
reduction in tree height by one leads to a decrease of one comparison and
one swap.
This optimization results in saving approximately 0.5 * n swaps without
increasing the number of comparisons. Additionally, the heap size during
heapify is now one less than the original size, offering a chance for
further reduction in comparisons and swaps.
The following experimental data is based on the array generated using
get_random_u32().
| N | swaps (old) | swaps (new) | comparisons (old) | comparisons (new) |
|-------|-------------|-------------|-------------------|-------------------|
| 1000 | 9054 | 8569 | 10328 | 10320 |
| 2000 | 20137 | 19182 | 22634 | 22587 |
| 3000 | 32062 | 30623 | 35833 | 35752 |
| 4000 | 44274 | 42282 | 49332 | 49306 |
| 5000 | 57195 | 54676 | 63300 | 63294 |
| 6000 | 70205 | 67202 | 77599 | 77557 |
| 7000 | 83276 | 79831 | 92113 | 92032 |
| 8000 | 96630 | 92678 | 106635 | 106617 |
| 9000 | 110349 | 105883 | 121505 | 121404 |
| 10000 | 124165 | 119202 | 136628 | 136617 |
Link: https://lkml.kernel.org/r/20240113031352.2395118-3-visitorckw@gmail.com
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Cc: Ching-Chun (Jim) Huang <jserv@ccns.ncku.edu.tw>
Cc: George Spelvin <lkml@sdf.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "lib/sort: Optimize the number of swaps and comparisons".
This patch series aims to optimize the heapsort algorithm, specifically
targeting a reduction in the number of swaps and comparisons required.
This patch (of 2):
Currently, when searching for the sift-down path and encountering equal
elements, the algorithm chooses the left child. However, considering that
the height of the right subtree may be one less than that of the left
subtree, selecting the right child in such cases can potentially reduce
the number of comparisons and swaps.
For instance, when sorting an array of 10,000 identical elements, the
current implementation requires 247,209 comparisons. With this patch, the
number of comparisons can be reduced to 227,241.
Link: https://lkml.kernel.org/r/20240113031352.2395118-1-visitorckw@gmail.com
Link: https://lkml.kernel.org/r/20240113031352.2395118-2-visitorckw@gmail.com
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
XArray multi-index entries do not keep track of the order stored once the
entry is being marked as used with cmpxchg (conditionally replaced with
NULL). Add a test to check the order is actually lost. The test also
verifies the order and entries for all the tied indexes before and after
the NULL replacement with xa_cmpxchg.
Add another entry at 1 << order that keeps the node around and the order
information for the NULL-entry after xa_cmpxchg.
Link: https://lkml.kernel.org/r/20240131225125.1370598-3-mcgrof@kernel.org
Signed-off-by: Daniel Gomez <da.gomez@samsung.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "test_xarray: advanced API multi-index tests", v2.
This is a respin of the test_xarray multi-index tests [0] which use and
demonstrate the advanced API which is used by the page cache. This should
let folks more easily follow how we use multi-index to support for example
a min order later in the page cache. It also lets us grow the selftests
to mimic more of what we do in the page cache.
This patch (of 2):
The multi index selftests are great but they don't replicate how we deal
with the page cache exactly, which makes it a bit hard to follow as the
page cache uses the advanced API.
Add tests which use the advanced API, mimicking what we do in the page
cache, while at it, extend the example to do what is needed for min order
support.
[mcgrof@kernel.org: fix soft lockup for advanced-api tests]
Link: https://lkml.kernel.org/r/20240216194329.840555-1-mcgrof@kernel.org
[akpm@linux-foundation.org: s/i/loops/, make non-static]
[akpm@linux-foundation.org: restore static storage for loop counter]
Link: https://lkml.kernel.org/r/20240131225125.1370598-1-mcgrof@kernel.org
Link: https://lkml.kernel.org/r/20240131225125.1370598-2-mcgrof@kernel.org
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Tested-by: Daniel Gomez <da.gomez@samsung.com>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The local variables r_tmp and l_tmp in mast_spanning_rebalance() are
already initialized at its declaration; there is no need to assign the
value again.
Remove the duplicate initialization of {r,l}_tmp. No functional change.
Due to common compiler optimizations, also no change to object code.
This issue was identified with clang-analyzer's dead stores analysis.
Link: https://lkml.kernel.org/r/20240122102000.29558-1-lukas.bulwahn@gmail.com
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pull simple offset series from Chuck Lever
In an effort to address slab fragmentation issues reported a few
months ago, I've replaced the use of xarrays for the directory
offset map in "simple" file systems (including tmpfs).
Thanks to Liam Howlett for helping me get this working with Maple
Trees.
* series 'Use Maple Trees for simple_offset utilities' of https://lore.kernel.org/r/170820083431.6328.16233178852085891453.stgit@91.116.238.104.host.secureserver.net: (6 commits)
libfs: Convert simple directory offsets to use a Maple Tree
test_maple_tree: testing the cyclic allocation
maple_tree: Add mtree_alloc_cyclic()
libfs: Add simple_offset_empty()
libfs: Define a minimum directory offset
libfs: Re-arrange locking in offset_iterate_dir()
Signed-off-by: Christian Brauner <brauner@kernel.org>
Using sizeof(dst) for the "size" argument in strscpy() is the
overwhelmingly common case. Instead of requiring this everywhere, allow a
2-argument version to be used that will use the sizeof() internally. There
are other functions in the kernel with optional arguments[1], so this
isn't unprecedented, and improves readability. Update and relocate the
kern-doc for strscpy() too, and drop __HAVE_ARCH_STRSCPY as it is unused.
Adjust ARCH=um build to notice the changed export name, as it doesn't
do full header includes for the string helpers.
This could additionally let us save a few hundred lines of code:
1177 files changed, 2455 insertions(+), 3026 deletions(-)
with a treewide cleanup using Coccinelle:
@needless_arg@
expression DST, SRC;
@@
strscpy(DST, SRC
-, sizeof(DST)
)
Link: https://elixir.bootlin.com/linux/v6.7/source/include/linux/pci.h#L1517 [1]
Reviewed-by: Justin Stitt <justinstitt@google.com>
Cc: Andy Shevchenko <andy@kernel.org>
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
In preparation for making strscpy_pad()'s 3rd argument optional, redefine
it as a macro. This also has the benefit of allowing greater FORITFY
introspection, as it couldn't see into the strscpy() nor the memset()
within strscpy_pad().
Cc: Andy Shevchenko <andy@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: <linux-hardening@vger.kernel.org>
Reviewed-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
In order to mitigate unexpected signed wrap-around[1], bring back the
signed integer overflow sanitizer. It was removed in commit 6aaa31aeb9
("ubsan: remove overflow checks") because it was effectively a no-op
when combined with -fno-strict-overflow (which correctly changes signed
overflow from being "undefined" to being explicitly "wrap around").
Compilers are adjusting their sanitizers to trap wrap-around and to
detecting common code patterns that should not be instrumented
(e.g. "var + offset < var"). Prepare for this and explicitly rename
the option from "OVERFLOW" to "WRAP" to more accurately describe the
behavior.
To annotate intentional wrap-around arithmetic, the helpers
wrapping_add/sub/mul_wrap() can be used for individual statements. At
the function level, the __signed_wrap attribute can be used to mark an
entire function as expecting its signed arithmetic to wrap around. For a
single object file the Makefile can use "UBSAN_SIGNED_WRAP_target.o := n"
to mark it as wrapping, and for an entire directory, "UBSAN_SIGNED_WRAP :=
n" can be used.
Additionally keep these disabled under CONFIG_COMPILE_TEST for now.
Link: https://github.com/KSPP/linux/issues/26 [1]
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Hao Luo <haoluo@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Trying to run the iov_iter unit test on a nommu system such as the qemu
kc705-nommu emulation results in a crash.
KTAP version 1
# Subtest: iov_iter
# module: kunit_iov_iter
1..9
BUG: failure at mm/nommu.c:318/vmap()!
Kernel panic - not syncing: BUG!
The test calls vmap() directly, but vmap() is not supported on nommu
systems, causing the crash. TEST_IOV_ITER therefore needs to depend on
MMU.
Link: https://lkml.kernel.org/r/20240208153010.1439753-1-linux@roeck-us.net
Fixes: 2d71340ff1 ("iov_iter: Kunit tests for copying to/from an iterator")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Cc: David Howells <dhowells@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
'def_bool X' is a shorthand for 'bool' plus 'default X'.
'def_bool' is redundant where 'bool' is already present, so 'def_bool X'
can be replaced with 'default X', or removed if X is 'n'.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Pull driver core fixes from Greg KH:
"Here are some driver core fixes, a kobject fix, and a documentation
update for 6.8-rc5. In detail these changes are:
- devlink fixes for reported issues with 6.8-rc1
- topology scheduling regression fix that has been reported by many
- kobject loosening of checks change in -rc1 is now reverted as some
codepaths seemed to need the checks
- documentation update for the CVE process. Has been reviewed by
many, the last minute change to the document was to bring the .rst
format back into the the new style rules, the contents did not
change.
All of these, except for the documentation update, have been in
linux-next for over a week. The documentation update has been reviewed
for weeks by a group of developers, and in public for a week and the
wording has stabilized for now. If future changes are needed, we can
do so before 6.8-final is out (or anytime after that)"
* tag 'driver-core-6.8-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
Documentation: Document the Linux Kernel CVE process
Revert "kobject: Remove redundant checks for whether ktype is NULL"
driver core: fw_devlink: Improve logs for cycle detection
driver core: fw_devlink: Improve detection of overlapping cycles
driver core: Fix device_link_flag_is_sync_state_only()
topology: Set capacity_freq_ref in all cases
This is a followup of commit a3498436b3 ("netns: restrict uevents")
- uevent_sock_mutex no longer protects uevent_seqnum thanks
to prior patch in the series.
- uevent_net_broadcast() can run without holding uevent_sock_mutex.
- Instead of grabbing uevent_sock_mutex before calling
kobject_uevent_net_broadcast(), we can move the
mutex_lock(&uevent_sock_mutex) to the place we iterate over
uevent_sock_list : uevent_net_broadcast_untagged().
After this patch, typical netdevice creations and destructions
calling uevent_net_broadcast_tagged() no longer need to acquire
uevent_sock_mutex.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Christian Brauner <brauner@kernel.org>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20240214084829.684541-3-edumazet@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull tracing fixes from Steven Rostedt:
- Fix the #ifndef that didn't have the 'CONFIG_' prefix on
HAVE_DYNAMIC_FTRACE_WITH_REGS
The fix to have dynamic trampolines work with x86 broke arm64 as the
config used in the #ifdef was HAVE_DYNAMIC_FTRACE_WITH_REGS and not
CONFIG_HAVE_DYNAMIC_FTRACE_WITH_REGS which removed the fix that the
previous fix was to fix.
- Fix tracing_on state
The code to test if "tracing_on" is set incorrectly used
ring_buffer_record_is_on() which returns false if the ring buffer
isn't able to be written to.
But the ring buffer disable has several bits that disable it. One is
internal disabling which is used for resizing and other modifications
of the ring buffer. But the "tracing_on" user space visible flag
should only report if tracing is actually on and not internally
disabled, as this can cause confusion as writing "1" when it is
disabled will not enable it.
Instead use ring_buffer_record_is_set_on() which shows the user space
visible settings.
- Fix a false positive kmemleak on saved cmdlines
Now that the saved_cmdlines structure is allocated via alloc_page()
and not via kmalloc() it has become invisible to kmemleak. The
allocation done to one of its pointers was flagged as a dangling
allocation leak. Make kmemleak aware of this allocation and free.
- Fix synthetic event dynamic strings
An update that cleaned up the synthetic event code removed the return
value of trace_string(), and had it return zero instead of the
length, causing dynamic strings in the synthetic event to always have
zero size.
- Clean up documentation and header files for seq_buf
* tag 'trace-v6.8-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
seq_buf: Fix kernel documentation
seq_buf: Don't use "proxy" headers
tracing/synthetic: Fix trace_string() return value
tracing: Inform kmemleak of saved_cmdlines allocation
tracing: Use ring_buffer_record_is_set_on() in tracer_tracing_is_on()
tracing: Fix HAVE_DYNAMIC_FTRACE_WITH_REGS ifdef
Move the s390 specific raid6 inline assemblies, make them generic, and
reuse them to implement the raid6 gen/xor implementation.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
The kernel_fpu structure has a quite large size of 520 bytes. In order to
reduce stack footprint introduce several kernel fpu structures with
different and also smaller sizes. This way every kernel fpu user must use
the correct variant. A compile time check verifies that the correct variant
is used.
There are several users which use only 16 instead of all 32 vector
registers. For those users the new kernel_fpu_16 structure with a size of
only 266 bytes can be used.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Move, rename, and merge the fpu and vx header files. This way fpu header
files have a consistent naming scheme (fpu*.h).
Also get rid of the fpu subdirectory and move header files to asm
directory, so that all fpu and vx header files can be found at the same
location.
Merge internal.h header file into other header files, since the internal
helpers are used at many locations. so those helper functions are really
not internal.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Pull KUnit fix from Shuah Khan:
"One important fix to unregister kunit_bus when KUnit module is
unloaded.
Not doing so causes an error when KUnit module tries to re-register
the bus when it gets reloaded"
* tag 'linux_kselftest-kunit-fixes-6.8-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest:
kunit: device: Unregister the kunit_bus on shutdown
The pcim_*() functions in lib/devres.c are guarded by an #ifdef CONFIG_PCI
and, thus, don't belong to this file. They are only ever used for PCI and
are not generic infrastructure.
Move all pcim_*() functions in lib/devres.c to drivers/pci/devres.c.
Adjust the Makefile.
Add drivers/pci/devres.c to Documentation.
Link: https://lore.kernel.org/r/20240131090023.12331-4-pstanner@redhat.com
Suggested-by: Danilo Krummrich <dakr@redhat.com>
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Code sections in s390 specific kernel code which use floating point or
vector registers all come with a 520 byte stack variable to save already in
use registers, if required.
With INIT_STACK_ALL_PATTERN or INIT_STACK_ALL_ZERO enabled this variable
will always be initialized on function entry in addition to saving register
contents, which contradicts the intention (performance improvement) of such
code sections.
Therefore provide a DECLARE_KERNEL_FPU_ONSTACK() macro which provides
struct kernel_fpu variables with an __uninitialized attribute, and convert
all existing code to use this.
This way only this specific type of stack variable will not be initialized,
regardless of config options.
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20240205154844.3757121-3-hca@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
dump_stack() is called in panic(). If for some reason another CPU
is holding the printk_cpu_sync and is unable to release it, the
panic CPU will be unable to continue and print the stacktrace.
Since non-panic CPUs are not allowed to store new printk messages
anyway, there is no need to synchronize the stacktrace output in
a panic situation.
For the panic CPU, do not get the printk_cpu_sync because it is
not needed and avoids a potential deadlock scenario in panic().
Link: https://lore.kernel.org/lkml/ZcIGKU8sxti38Kok@alley
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20240207134103.1357162-15-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>
If KUnit is built as a module, and it's unloaded, the kunit_bus is not
unregistered. This causes an error if it's then re-loaded later, as we
try to re-register the bus.
Unregister the bus and root_device on shutdown, if it looks valid.
In addition, be more specific about the value of kunit_bus_device. It
is:
- a valid struct device* if the kunit_bus initialised correctly.
- an ERR_PTR if it failed to initialise.
- NULL before initialisation and after shutdown.
Fixes: d03c720e03 ("kunit: Add APIs for managing devices")
Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Rae Moar <rmoar@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
For simplicity in splitting out UBSan options into separate rules,
remove CONFIG_UBSAN_SANITIZE_ALL, effectively defaulting to "y", which
is how it is generally used anyway. (There are no ":= y" cases beyond
where a specific file is enabled when a top-level ":= n" is in effect.)
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Marco Elver <elver@google.com>
Cc: linux-doc@vger.kernel.org
Cc: linux-kbuild@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
lib/test_blackhole_dev.c sets a variable that is never read, causing
this following building warning:
lib/test_blackhole_dev.c:32:17: warning: variable 'ethh' set but not used [-Wunused-but-set-variable]
Remove the variable struct ethhdr *ethh, which is unused.
Fixes: 509e56b37c ("blackhole_dev: add a selftest")
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Fix all kernel-doc warnings in test_kmod.c:
- Mark some enum values as private so that kernel-doc is not needed
for them
- s/thread_mutex/thread_lock/ in a struct's kernel-doc comments
- add kernel-doc info for @task_sync
test_kmod.c:67: warning: Enum value '__TEST_KMOD_INVALID' not described in enum 'kmod_test_case'
test_kmod.c:67: warning: Enum value '__TEST_KMOD_MAX' not described in enum 'kmod_test_case'
test_kmod.c💯 warning: Function parameter or member 'task_sync' not described in 'kmod_test_device_info'
test_kmod.c:134: warning: Function parameter or member 'thread_mutex' not described in 'kmod_test_device'
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: <linux-modules@vger.kernel.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
The loop counter "i" in copy_compat_iovec_from_user() is an int, but
because the nr_segs argument is unsigned long, the signed overflow
sanitizer got worried "i" could wrap around. Instead of making "i" an
unsigned long (which may enlarge the type size), switch both nr_segs
and i to u32. There is no truncation with nr_segs since it is never
larger than UIO_MAXIOV anyway. This keeps sanitizer instrumentation[1]
out of a UACCESS path:
vmlinux.o: warning: objtool: copy_compat_iovec_from_user+0xa9: call to __ubsan_handle_add_overflow() with UACCESS enabled
Link: https://github.com/KSPP/linux/issues/26 [1]
Cc: Christian Brauner <brauner@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20240129183729.work.991-kees@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Similarly to cpumask_weight_and(), cpumask_weight_andnot() is a handy
helper that may help to avoid creating an intermediate mask just to
calculate number of bits that set in a 1st given mask, and clear in 2nd
one.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Pull kunit fixes from Shuah Khan:
"NULL vs IS_ERR() bug fixes, documentation update, MAINTAINERS file
update to add Rae Moar as a reviewer, and a fix to run test suites
only after module initialization completes"
* tag 'linux_kselftest-kunit-fixes-6.8-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest:
Documentation: KUnit: Update the instructions on how to test static functions
kunit: run test suites only after module initialization completes
MAINTAINERS: kunit: Add Rae Moar as a reviewer
kunit: device: Fix a NULL vs IS_ERR() check in init()
kunit: Fix a NULL vs IS_ERR() bug
With the introduction of the pool_rwlock (reader-writer lock), several
fast paths end up taking the pool_rwlock as readers. Furthermore,
stack_depot_put() unconditionally takes the pool_rwlock as a writer.
Despite allowing readers to make forward-progress concurrently,
reader-writer locks have inherent cache contention issues, which does not
scale well on systems with large CPU counts.
Rework the synchronization story of stack depot to again avoid taking any
locks in the fast paths. This is done by relying on RCU-protected list
traversal, and the NMI-safe subset of RCU to delay reuse of freed stack
records. See code comments for more details.
Along with the performance issues, this also fixes incorrect nesting of
rwlock within a raw_spinlock, given that stack depot should still be
usable from anywhere:
| [ BUG: Invalid wait context ]
| -----------------------------
| swapper/0/1 is trying to lock:
| ffffffff89869be8 (pool_rwlock){..--}-{3:3}, at: stack_depot_save_flags
| other info that might help us debug this:
| context-{5:5}
| 2 locks held by swapper/0/1:
| #0: ffffffff89632440 (rcu_read_lock){....}-{1:3}, at: __queue_work
| #1: ffff888100092018 (&pool->lock){-.-.}-{2:2}, at: __queue_work <-- raw_spin_lock
Stack depot usage stats are similar to the previous version after a KASAN
kernel boot:
$ cat /sys/kernel/debug/stackdepot/stats
pools: 838
allocations: 29865
frees: 6604
in_use: 23261
freelist_size: 1879
The number of pools is the same as previously. The freelist size is
minimally larger, but this may also be due to variance across system
boots. This shows that even though we do not eagerly wait for the next
RCU grace period (such as with synchronize_rcu() or call_rcu()) after
freeing a stack record - requiring depot_pop_free() to "poll" if an entry
may be used - new allocations are very likely to happen in later RCU grace
periods.
Link: https://lkml.kernel.org/r/20240118110216.2539519-2-elver@google.com
Fixes: 108be8def4 ("lib/stackdepot: allow users to evict stack traces")
Reported-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Marco Elver <elver@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add a few basic stats counters for stack depot that can be used to derive
if stack depot is working as intended. This is a snapshot of the new
stats after booting a system with a KASAN-enabled kernel:
$ cat /sys/kernel/debug/stackdepot/stats
pools: 838
allocations: 29861
frees: 6561
in_use: 23300
freelist_size: 1840
Generally, "pools" should be well below the max; once the system is
booted, "in_use" should remain relatively steady.
Link: https://lkml.kernel.org/r/20240118110216.2539519-1-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
