Re: Bisected: [PATCH v7 2/8] hugetlb: restructure pool allocations

[Mike Kravetz]

On 10/19/23 11:15, Sergey Senozhatsky wrote:
> On (23/10/18 15:44), Mike Kravetz wrote:
> > Hi Sergey,
> > 
> > Sorry for the delay.  Not ignoring your report but chasing this in
> > another thread.
> 
> Hi Mike, no worries.
> 
> > https://lore.kernel.org/linux-mm/20231018222003.GA21776@monkey/
> 
> Oh, interesting.
> I just read the article the other day about some of unexpected optimizations
> that clang can do [1].
> 
> Setting h to NULL seems to be fixing the problem for me.
> 
> > Quick question.
> > Are you using LLVM/clang in your builds?
> 
> Yes, clang 14.0.6
> The kernel compiled with gcc does not BUG_ON().
> 
> > My guess is that you are hitting the same issue.  That BUG at mm/hugetlb.c:3180
> > should not be checked/executed unless you allocate gigantic hugetlb pages on
> > the kernel command line.  Suspect you are not doing this, and loop code is
> > being run when it should not.
> 
> Looks very similar indeed.
> 
> [1] https://research.swtch.com/ub

Thank you for testing!
-- 
Mike Kravetz