Re: [PATCH v3 4/4] mm/page_alloc: remove a couple of VM_BUG_ON()st

["Brendan Jackman" <brendan.jackman@linux.dev>]

On Wed Jul 15, 2026 at 1:25 PM UTC, Vlastimil Babka (SUSE) wrote:
> Subject has stray 't' at the end?

Thanks - will fix if we do a v3 (otherwise Andrew, please can you amend
when you apply it?)

> On 7/15/26 13:03, Brendan Jackman wrote:
>> VM_BUG_ON() is out of favour and on the way to removal, since I recently
>> touched alloc_pages_node_noprof() I am removing that invocation, and
>> also removing the __folio_alloc_node_noprof() one for consistency. If
>> this precondition is violated, the system will soon crash anyway.
>> 
>> Suggested-by: Zi Yan <ziy@nvidia.com>
>> Link: https://lore.kernel.org/all/7F866265-3F2E-4765-B9D4-9AB898A9C4AC@nvidia.com/
>> Acked-by: Zi Yan <ziy@nvidia.com>
>> Signed-off-by: Brendan Jackman <jackmanb@google.com>
>
> Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
>
>> ---
>>  include/linux/gfp.h | 1 -
>>  mm/page_alloc.c     | 1 -
>>  2 files changed, 2 deletions(-)
>> 
>> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
>> index 4d57e9c0bf204..872bc53f32ec8 100644
>> --- a/include/linux/gfp.h
>> +++ b/include/linux/gfp.h
>> @@ -255,7 +255,6 @@ static inline void warn_if_node_offline(int this_node, gfp_t gfp_mask)
>>  static inline
>>  struct folio *__folio_alloc_node_noprof(gfp_t gfp, unsigned int order, int nid)
>>  {
>> -	VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES);
>>  	warn_if_node_offline(nid, gfp);
>>  
>>  	return __folio_alloc_noprof(gfp, order, nid, NULL);
>
> Well if you want more cleanups, I can see in iommu_alloc_pages_node_sz():
>
>
>         /*
>          * __folio_alloc_node() does not handle NUMA_NO_NODE like
>          * alloc_pages_node() did.
>          */
>         if (nid == NUMA_NO_NODE)
>                 nid = numa_mem_id();
>
>         folio = __folio_alloc_node(gfp | __GFP_ZERO, order, nid);
>
> Should we introduce folio_alloc_node() and make __folio_alloc_node()
> mm-internal, for consistency?

Ha, I literally just wrote that patch. I'm planning to do it as yet
another series as there's a little dance needed to get it all into
shape. But, also happy to just expand this one if you prefer.

Then I'm gonna add alloc_flags to the __ variant so filemap.c can set
ALLOC_UNMAPPED for AS_NO_DIRECT_MAP.