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53bc5c556b
set_tsk_need_resched() tests TIF_NEED_RESCHED, calls
__trace_set_need_resched() if the flag is clear, then sets it via
set_tsk_thread_flag(). A BPF raw_tp program attached to
sched_set_need_resched executes synchronously inside __bpf_trace_run().
On return, __bpf_trace_run() drops the RCU lock with
rcu_read_unlock_migrate(), which on the preempt-or-BH-disabled path
calls set_need_resched_current() -> set_tsk_need_resched() again.
set_tsk_thread_flag() follows the tracepoint call, so every re-entrant
frame sees TIF_NEED_RESCHED clear and calls __trace_set_need_resched()
again:
BUG: TASK stack guard page was hit at ffffc9001224ff98
Oops: stack guard page: 0000 [#1] SMP KASAN PTI
RIP: 0010:__bpf_trace_sched_set_need_resched_tp+0x1c/0x190
Call Trace:
trace_sched_set_need_resched_tp+0x110/0x130
set_tsk_need_resched include/linux/sched.h:2076
set_need_resched_current include/linux/sched.h:2094
rcu_read_unlock_special+0x43a/0x440
__rcu_read_unlock+0x9e/0x120
rcu_read_unlock_migrate+0xa9/0x240
__bpf_trace_run+0x131/0x180
bpf_trace_run3+0x333/0x430
__bpf_trace_sched_set_need_resched_tp+0x13a/0x190
trace_sched_set_need_resched_tp+0x110/0x130
set_tsk_need_resched include/linux/sched.h:2076
...
__resched_curr() has the same ordering, firing the tracepoint before
setting the flag via set_ti_thread_flag() or set_nr_and_not_polling().
Fix it for consistency.
Replace the separate test_tsk_thread_flag() + set_tsk_thread_flag() pair
in set_tsk_need_resched() with test_and_set_tsk_thread_flag(). In
__resched_curr(), move the tracepoint call after the flag is set in
each path.
Fixes:
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| acpi | ||
| asm-generic | ||
| clocksource | ||
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