Re: [PATCH] hugetlb: add cond_resched() to __unmap_hugepage_range()

[Matthew Wilcox <willy@infradead.org>]

On Tue, Aug 18, 2026 at 04:24:30PM -0700, Andrew Morton wrote:
> On Wed, 19 Aug 2026 06:18:58 +0800 Lance Yang <lance.yang@linux.dev> wrote:
> 
> > >> > 
> > >> > That's pretty bad behavior and we might want to fix it in earlier
> > >> > kernels.  Is PREEMPT_NONE effectively dead in 6.18.x and its
> > >> > existing users?
> > >> > 
> > >> > If yes, we do want to fix older kernels then we should merge this.
> > >> > 
> > >> 
> > >> Okay, but that would be stable-only fixes?
> > >
> > >Not understanding.
> > >
> > >Maybe you refer to adding a patch to -stable but not to -linus?  That's
> > >against the -stable rules
> > >(Documentation/process/stable-kernel-rules.rst).
> > 
> > Since cond_resched() is a scheduling no-op under LAZY/FULL anyway (only
> > the __might_resched() debug check remains), why not take this upstream
> > with Cc: stable?
> 
> I think so - as long as PREEPMT_NONE exists we should support it as
> well as we can.  If the day comes that PREEMPT_NONE is removed, then we
> get to remove lots of cond_resched()s.  mm/ has 200 of the things.
> 
> > Mainline scheduling stays unchanged, and stable can pick it up for old
> > PREEMPT_NONE kernels. wdyt?
> 
> Addressing this issue in older kernels is another reason.

That is not the direction that the scheduler developers wish us to take.