On Tue, Jun 14, 2022 at 9:11 AM Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote: > > On 2022-06-13 23:13:49 [+0200], Arnd Bergmann wrote: > > Acked-by: Arnd Bergmann <arnd@xxxxxxxx> > > > > It's probably best to keep this together with the corresponding architecture > > specific changes. I was a bit worried about bisection at first, but > > then realized > > that this is not a problem for mainline since ARCH_SUPPORTS_RT is not > > yet enabled on any architecture. > > So where do I put this patch to? If I remember correctly then arm64 is > using this. ARM has its own thing and x86 has this change already. I don't see HAVE_SOFTIRQ_ON_OWN_STACK for arm, parisc, powerpc, s390, sh, sparc and x86, but not arm64. I would suggest having a single patch that does the same change across all architectures that don't already do this, and then merging it either through tip or through my asm-generic tree. > - ksoftirqd thread. > - in the force-threaded interrupt after the main handler. > - any time after bh-counter hits zero due local_bh_enable(). > > The last one will cause higher task stacks. Does this mean it only happens when a softirq gets raised from task context (which would be predictable), or also at an arbitrary time if it gets raised by a non-threaded hardirq or IPI? Arnd