Re: [Question] Question about GFP_ATOMIC allocations on PREEMPT_RT kernel

[Yeoreum Yun <yeoreum.yun@arm.com>]

Hi Harry,

[...]
>
> You're not supposed allocate (even with GFP_ATOMIC) or free memory on
> PREEMPT_RT in non-threaded interrupt context [1].
>
> I think it somwhow implied in [2]? (Ok, probably not that obvious)
>
> "Acquiring a raw_spinlock_t disables preemption and possibly also
> interrupts, so the critical section must avoid acquiring a regular
> spinlock_t or rwlock_t, for example, the critical section must avoid
> allocating memory."
>
> "But this code fails on PREEMPT_RT kernels because the memory allocator
> is fully preemptible and therefore cannot be invoked from truly atomic
> contexts."
>
> [1] https://lore.kernel.org/linux-mm/YwZSUpYY9l442Lxr@linutronix.de
>
> [2] https://www.kernel.org/doc/html/latest/locking/locktypes.html#raw-spinlock-t-on-rt
>

Thanks for clear reference :D
I miss the clause of [2]...

--
Sincerely,
Yeoreum Yun
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