On 17.10.2025 11:23, Roger Pau Monné wrote:
> On Thu, Oct 16, 2025 at 09:31:21AM +0200, Jan Beulich wrote:
>> Despite 1db7829e5657 ("x86/hpet: do local APIC EOI after interrupt
>> processing") we can still observe nested invocations of
>> hpet_interrupt_handler(). This is, afaict, a result of previously used
>> channels retaining their IRQ affinity until some other CPU re-uses them.
>> Such nesting is increasingly problematic with higher CPU counts, as both
>> handle_hpet_broadcast() and cpumask_raise_softirq() have a cpumask_t local
>> variable. IOW already a single level of nesting may require more stack
>> space (2 times above 4k) than we have available (8k), when NR_CPUS=16383
>> (the maximum value presently possible).
>>
>> Signed-off-by: Jan Beulich <[email protected]>
>> ---
>> Whether this is still worthwhile with "x86/HPET: use single, global, low-
>> priority vector for broadcast IRQ" isn't quite clear to me.
>
> Seeing the rest of the series, I don't think this is necessary
> anymore? Also the comment you here is made stale by the patch that
> uses a global vector.
Right now I'm not quite sure, hence the remark and the patch being part of
the series. If I re-work patch 3 to avoid the mask/unmask upon affinity
changes, I think the one here can indeed be dropped.
Jan
