Re: [External] Re: [PATCH] mm: hugetlb: Only prep and add allocated folios for non-gigantic pages

[Konrad Dybcio]

On 10/10/23 23:30, Mike Kravetz wrote:
> On 10/10/23 18:01, Usama Arif wrote:
> > On 10/10/2023 02:23, Mike Kravetz wrote:
> > > On 10/09/23 15:56, Usama Arif wrote:
> > > > Calling prep_and_add_allocated_folios when allocating gigantic pages
> > > > at boot time causes the kernel to crash as folio_list is empty
> > > > and iterating it causes a NULL pointer dereference. Call this only
> > > > for non-gigantic pages when folio_list has entires.
> > >
> > > Thanks!
> > >
> > > However, are you sure the issue is the result of iterating through a
> > > NULL list?  For reference, the routine prep_and_add_allocated_folios is:
> >
> > Yes, you are right, it wasnt an issue with the list, but the lock. If I do
> > the below diff it boots.
>
> Thanks!
>
> I believe that may be that may be the root cause of boot issues with
> this series.  It is unfortunate that the failures were not consistent
> and did not directly point at the root cause.
>
> Hopefully, these changes will resolve the boot issues for Konrad as well.
>
> I will create a new version of the "Batch hugetlb vmemmap modification
> operations" series with these locking changes.
We sent a reply at the same time :P [1]

Konrad

[1] 
https://lore.kernel.org/all/6f381d4c-d908-4f00-89b3-ed3bcb26b143@xxxxxxxxxx/