Re: Sleeping BUG in khugepaged for i586

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu 08-06-17 16:48:31, Michal Hocko wrote:
> On Wed 07-06-17 13:56:01, David Rientjes wrote:
> > On Wed, 7 Jun 2017, Vlastimil Babka wrote:
> > 
> > > >> Hmm I'd expect such spin lock to be reported together with mmap_sem in
> > > >> the debugging "locks held" message?
> > > > 
> > > > My bisection of the problem is about half done. My latest good version is commit 
> > > > 7b8cd33 and the latest bad one is 2ea659a. Only about 7 steps to go.
> > > 
> > > Hmm, your bisection will most likely just find commit 338a16ba15495
> > > which added the cond_resched() at mm/khugepaged.c:655. CCing David who
> > > added it.
> > > 
> > 
> > I agree it's probably going to bisect to 338a16ba15495 since it's the 
> > cond_resched() at the line number reported, but I think there must be 
> > something else going on.  I think the list of locks held by khugepaged is 
> > correct because it matches with the implementation.  The preempt_count(), 
> > as suggested by Andrew, does not.  If this is reproducible, I'd like to 
> > know what preempt_count() is.
> 
> collapse_huge_page
>   pte_offset_map
>     kmap_atomic
>       kmap_atomic_prot
>         preempt_disable
>   __collapse_huge_page_copy
>   pte_unmap
>     kunmap_atomic
>       __kunmap_atomic
>         preempt_enable
> 
> I suspect, so cond_resched seems indeed inappropriate on 32b systems.

The code still seems to be in the mmotm tree. Are there any plans to fix
this or drop the patch?
-- 
Michal Hocko
SUSE Labs

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>



[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Bugtraq]     [Linux OMAP]     [Linux MIPS]     [eCos]     [Asterisk Internet PBX]     [Linux API]
  Powered by Linux