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

["Vlastimil Babka (SUSE)" <vbabka@kernel.org>]

On 7/15/26 15:48, Brendan Jackman wrote:
> 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

Cool!

> shape. But, also happy to just expand this one if you prefer.

Not necessary, another series is fine.

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

Great!