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Dapeng Mi eb3182ef04 perf/core: Fix system hang caused by cpu-clock usage 
cpu-clock usage by the async-profiler tool can trigger a system hang,
which got bisected back to the following commit by Octavia Togami:

  18dbcbfabf ("perf: Fix the POLL_HUP delivery breakage") causes this issue

The root cause of the hang is that cpu-clock is a special type of SW
event which relies on hrtimers. The __perf_event_overflow() callback
is invoked from the hrtimer handler for cpu-clock events, and
__perf_event_overflow() tries to call cpu_clock_event_stop()
to stop the event, which calls htimer_cancel() to cancel the hrtimer.

But that's a recursion into the hrtimer code from a hrtimer handler,
which (unsurprisingly) deadlocks.

To fix this bug, use hrtimer_try_to_cancel() instead, and set
the PERF_HES_STOPPED flag, which causes perf_swevent_hrtimer()
to stop the event once it sees the PERF_HES_STOPPED flag.

[ mingo: Fixed the comments and improved the changelog. ]

Closes: https://lore.kernel.org/all/CAHPNGSQpXEopYreir+uDDEbtXTBvBvi8c6fYXJvceqtgTPao3Q@mail.gmail.com/
Fixes: 18dbcbfabf ("perf: Fix the POLL_HUP delivery breakage")
Reported-by: Octavia Togami <octavia.togami@gmail.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Octavia Togami <octavia.togami@gmail.com>
Cc: stable@vger.kernel.org
Link: https://github.com/lucko/spark/issues/530
Link: https://patch.msgid.link/20251015051828.12809-1-dapeng1.mi@linux.intel.com
 		2025-11-03 11:04:19 +01:00
..
Makefile perf/hw_breakpoint: Add KUnit test for constraints accounting 2022-08-30 10:56:20 +02:00
callchain.c perf: Simplify get_perf_callchain() user logic 2025-08-26 09:51:13 +02:00
core.c perf/core: Fix system hang caused by cpu-clock usage 2025-11-03 11:04:19 +01:00
hw_breakpoint.c perf/hw_breakpoint: Return EOPNOTSUPP for unsupported breakpoint type 2025-03-04 09:42:13 +01:00
hw_breakpoint_test.c perf/hw_breakpoint: remove MODULE_LICENSE in non-modules 2023-04-13 13:13:52 -07:00
internal.h perf: Convert mmap() refcounts to refcount_t 2025-08-15 13:13:02 +02:00
ring_buffer.c perf: Convert mmap() refcounts to refcount_t 2025-08-15 13:13:02 +02:00
uprobes.c uprobe: Move arch_uprobe_optimize right after handlers execution 2025-10-14 10:38:09 +02:00