| Message ID | 20230408052226.25268-1-Tze-nan.Wu@mediatek.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | ring-buffer: Prevent inconsistent operation on cpu_buffer->resize_disabled | expand |
Hi Tze-nan,
kernel test robot noticed the following build warnings:
[auto build test WARNING on linus/master]
[also build test WARNING on rostedt-trace/for-next v6.3-rc5 next-20230406]
[cannot apply to rostedt-trace/for-next-urgent]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Tze-nan-Wu/ring-buffer-Prevent-inconsistent-operation-on-cpu_buffer-resize_disabled/20230408-132502
patch link: https://lore.kernel.org/r/20230408052226.25268-1-Tze-nan.Wu%40mediatek.com
patch subject: [PATCH] ring-buffer: Prevent inconsistent operation on cpu_buffer->resize_disabled
config: x86_64-randconfig-a002-20230403 (https://download.01.org/0day-ci/archive/20230408/202304081615.eiaqpbV8-lkp@intel.com/config)
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/d404bc0af0a4bde3aa20704642d69a78bdc154f8
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Tze-nan-Wu/ring-buffer-Prevent-inconsistent-operation-on-cpu_buffer-resize_disabled/20230408-132502
git checkout d404bc0af0a4bde3aa20704642d69a78bdc154f8
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash kernel/trace/
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202304081615.eiaqpbV8-lkp@intel.com/
All warnings (new ones prefixed by >>):
>> kernel/trace/ring_buffer.c:5359:15: warning: variable 'reset_online_mask' is uninitialized when used here [-Wuninitialized]
cpumask_copy(reset_online_mask, cpu_online_mask);
^~~~~~~~~~~~~~~~~
kernel/trace/ring_buffer.c:5353:33: note: initialize the variable 'reset_online_mask' to silence this warning
cpumask_var_t reset_online_mask;
^
= NULL
1 warning generated.
vim +/reset_online_mask +5359 kernel/trace/ring_buffer.c
5344
5345 /**
5346 * ring_buffer_reset_online_cpus - reset a ring buffer per CPU buffer
5347 * @buffer: The ring buffer to reset a per cpu buffer of
5348 * @cpu: The CPU buffer to be reset
5349 */
5350 void ring_buffer_reset_online_cpus(struct trace_buffer *buffer)
5351 {
5352 struct ring_buffer_per_cpu *cpu_buffer;
5353 cpumask_var_t reset_online_mask;
5354 int cpu;
5355
5356 /* prevent another thread from changing buffer sizes */
5357 mutex_lock(&buffer->mutex);
5358
> 5359 cpumask_copy(reset_online_mask, cpu_online_mask);
5360
5361 for_each_cpu_and(cpu, buffer->cpumask, reset_online_mask) {
5362 cpu_buffer = buffer->buffers[cpu];
5363
5364 atomic_inc(&cpu_buffer->resize_disabled);
5365 atomic_inc(&cpu_buffer->record_disabled);
5366 }
5367
5368 /* Make sure all commits have finished */
5369 synchronize_rcu();
5370
5371 for_each_cpu_and(cpu, buffer->cpumask, reset_online_mask) {
5372 cpu_buffer = buffer->buffers[cpu];
5373
5374 reset_disabled_cpu_buffer(cpu_buffer);
5375
5376 atomic_dec(&cpu_buffer->record_disabled);
5377 atomic_dec(&cpu_buffer->resize_disabled);
5378 }
5379
5380 mutex_unlock(&buffer->mutex);
5381 }
5382
Hi Tze-nan,
kernel test robot noticed the following build warnings:
[auto build test WARNING on linus/master]
[cannot apply to rostedt-trace/for-next-urgent]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Tze-nan-Wu/ring-buffer-Prevent-inconsistent-operation-on-cpu_buffer-resize_disabled/20230408-132502
patch link: https://lore.kernel.org/r/20230408052226.25268-1-Tze-nan.Wu%40mediatek.com
patch subject: [PATCH] ring-buffer: Prevent inconsistent operation on cpu_buffer->resize_disabled
config: s390-allyesconfig (https://download.01.org/0day-ci/archive/20230408/202304082051.Dp50upfS-lkp@intel.com/config)
compiler: s390-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/d404bc0af0a4bde3aa20704642d69a78bdc154f8
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Tze-nan-Wu/ring-buffer-Prevent-inconsistent-operation-on-cpu_buffer-resize_disabled/20230408-132502
git checkout d404bc0af0a4bde3aa20704642d69a78bdc154f8
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=s390 olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=s390 SHELL=/bin/bash kernel/
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202304082051.Dp50upfS-lkp@intel.com/
All warnings (new ones prefixed by >>):
kernel/trace/ring_buffer.c: In function 'ring_buffer_reset_online_cpus':
>> kernel/trace/ring_buffer.c:5359:9: warning: 'reset_online_mask' is used uninitialized [-Wuninitialized]
5359 | cpumask_copy(reset_online_mask, cpu_online_mask);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/trace/ring_buffer.c:5353:23: note: 'reset_online_mask' was declared here
5353 | cpumask_var_t reset_online_mask;
| ^~~~~~~~~~~~~~~~~
vim +/reset_online_mask +5359 kernel/trace/ring_buffer.c
5344
5345 /**
5346 * ring_buffer_reset_online_cpus - reset a ring buffer per CPU buffer
5347 * @buffer: The ring buffer to reset a per cpu buffer of
5348 * @cpu: The CPU buffer to be reset
5349 */
5350 void ring_buffer_reset_online_cpus(struct trace_buffer *buffer)
5351 {
5352 struct ring_buffer_per_cpu *cpu_buffer;
5353 cpumask_var_t reset_online_mask;
5354 int cpu;
5355
5356 /* prevent another thread from changing buffer sizes */
5357 mutex_lock(&buffer->mutex);
5358
> 5359 cpumask_copy(reset_online_mask, cpu_online_mask);
5360
5361 for_each_cpu_and(cpu, buffer->cpumask, reset_online_mask) {
5362 cpu_buffer = buffer->buffers[cpu];
5363
5364 atomic_inc(&cpu_buffer->resize_disabled);
5365 atomic_inc(&cpu_buffer->record_disabled);
5366 }
5367
5368 /* Make sure all commits have finished */
5369 synchronize_rcu();
5370
5371 for_each_cpu_and(cpu, buffer->cpumask, reset_online_mask) {
5372 cpu_buffer = buffer->buffers[cpu];
5373
5374 reset_disabled_cpu_buffer(cpu_buffer);
5375
5376 atomic_dec(&cpu_buffer->record_disabled);
5377 atomic_dec(&cpu_buffer->resize_disabled);
5378 }
5379
5380 mutex_unlock(&buffer->mutex);
5381 }
5382
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 76a2d91eecad..468f46bba71e 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -288,9 +288,6 @@ EXPORT_SYMBOL_GPL(ring_buffer_event_data); #define for_each_buffer_cpu(buffer, cpu) \ for_each_cpu(cpu, buffer->cpumask) -#define for_each_online_buffer_cpu(buffer, cpu) \ - for_each_cpu_and(cpu, buffer->cpumask, cpu_online_mask) - #define TS_SHIFT 27 #define TS_MASK ((1ULL << TS_SHIFT) - 1) #define TS_DELTA_TEST (~TS_MASK) @@ -5353,12 +5350,15 @@ EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); void ring_buffer_reset_online_cpus(struct trace_buffer *buffer) { struct ring_buffer_per_cpu *cpu_buffer; + cpumask_var_t reset_online_mask; int cpu; /* prevent another thread from changing buffer sizes */ mutex_lock(&buffer->mutex); - for_each_online_buffer_cpu(buffer, cpu) { + cpumask_copy(reset_online_mask, cpu_online_mask); + + for_each_cpu_and(cpu, buffer->cpumask, reset_online_mask) { cpu_buffer = buffer->buffers[cpu]; atomic_inc(&cpu_buffer->resize_disabled); @@ -5368,7 +5368,7 @@ void ring_buffer_reset_online_cpus(struct trace_buffer *buffer) /* Make sure all commits have finished */ synchronize_rcu(); - for_each_online_buffer_cpu(buffer, cpu) { + for_each_cpu_and(cpu, buffer->cpumask, reset_online_mask) { cpu_buffer = buffer->buffers[cpu]; reset_disabled_cpu_buffer(cpu_buffer);
Sometimes, write to buffer_size_kb can be permanently failure if we change the cpu_online_mask between two for_each_online_buffer_cpu loops in function ring_buffer_reset_online_cpus. The number of increasing and decreasing on cpu_buffer->resize_disable may be inconsistent, leading the resize_disabled in some CPUs becoming none zero after ring_buffer_reset_online_cpus return. This issue can be reproduced by "echo 0 > trace" and hotplug cpu at the same time. After reproducing succeess, we can find out the attempt to write to buffer_size_kb node failure every time. This patch prevent the inconsistent increasing and decreasing on cpu_buffer->resize_disabled by copying the cpu_online_mask at the beginning of the function. But I wonder if there's any side-effect of this patch, since the behavior changed, if we turn on a cpu between the two loops, reset_disabled_cpu_buffer() of that cpu won't be run as before, meaning the cpu_buffer on that cpu just awake will not be cleaned up. Cc: stable@vger.kernel.org Signed-off-by: Tze-nan Wu <Tze-nan.Wu@mediatek.com> --- kernel/trace/ring_buffer.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)