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Age	Commit message (Collapse)	Author
2025-07-19	samples: enhance hung_task detector test with read-write semaphore support	Zi Li
	Extend the hung_task detector test module to include read-write semaphore support alongside existing mutex and semaphore tests. This module now creates additional debugfs files under <debugfs>/hung_task, namely 'rw_semaphore_read' and 'rw_semaphore_write', in addition to 'mutex' and 'semaphore'. Reading these files with multiple processes triggers a prolonged sleep (256 seconds) while holding the respective lock, enabling hung_task detector testing for various locking mechanisms. This change builds on the extensible hung_task_tests module, adding read-write semaphore functionality to improve test coverage for kernel locking primitives. The implementation ensures proper lock handling and includes checks to prevent redundant data reads. Usage is: > cd /sys/kernel/debug/hung_task > cat mutex & cat mutex # Test mutex blocking > cat semaphore & cat semaphore # Test semaphore blocking > cat rw_semaphore_write \ & cat rw_semaphore_read # Test rwsem blocking > cat rw_semaphore_write \ & cat rw_semaphore_write # Test rwsem blocking Update the Kconfig description to reflect the addition of read-write semaphore debugfs files. Link: https://lkml.kernel.org/r/20250627072924.36567-4-lance.yang@linux.dev Signed-off-by: Zi Li <zi.li@linux.dev> Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Cc: Anna Schumaker <anna.schumaker@oracle.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joel Granados <joel.granados@kernel.org> Cc: John Stultz <jstultz@google.com> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Mingzhe Yang <mingzhe.yang@ly.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Tomasz Figa <tfiga@chromium.org> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Cc: Yongliang Gao <leonylgao@tencent.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-05-11	samples: extend hung_task detector test with semaphore support	Zi Li
	Extend the existing hung_task detector test module to support multiple lock types, including mutex and semaphore, with room for future additions (e.g., spinlock, etc.). This module creates dummy files under <debugfs>/hung_task, such as 'mutex' and 'semaphore'. The read process on any of these files will sleep for enough long time (256 seconds) while holding the respective lock. As a result, the second process will wait on the lock for a prolonged duration and be detected by the hung_task detector. This change unifies the previous mutex-only sample into a single, extensible hung_task_tests module, reducing code duplication and improving maintainability. Usage is: > cd /sys/kernel/debug/hung_task > cat mutex & cat mutex # Test mutex blocking > cat semaphore & cat semaphore # Test semaphore blocking Update the Kconfig description to reflect multiple debugfs files support. Link: https://lkml.kernel.org/r/20250414145945.84916-4-ioworker0@gmail.com Signed-off-by: Lance Yang <ioworker0@gmail.com> Signed-off-by: Zi Li <amaindex@outlook.com> Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Cc: Anna Schumaker <anna.schumaker@oracle.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joel Granados <joel.granados@kernel.org> Cc: John Stultz <jstultz@google.com> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Mingzhe Yang <mingzhe.yang@ly.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Tomasz Figa <tfiga@chromium.org> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Cc: Yongliang Gao <leonylgao@tencent.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>