Re: [PATCH v2] mm/hugetlb: use kvmalloc_objs for hugetlb_fault_mutex_table

[Muchun Song <muchun.song@linux.dev>]

> On Oct 6, 2026, at 18:02, Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com> wrote:
> 
> On systems/VMs with a large number of CPUs (e.g. 4096), hugetlb_init()
> computes num_fault_mutexes = roundup_pow_of_two(8 * num_possible_cpus())
> = 32768.  The subsequent kmalloc for the mutex table can exceed
> MAX_PAGE_ORDER when struct mutex is enlarged by debug options like
> CONFIG_DEBUG_MUTEXES and CONFIG_DEBUG_LOCK_ALLOC, resulting in:
> 
>  WARNING: at __alloc_frozen_pages_noprof (order > MAX_PAGE_ORDER)
>  kernel BUG at mm/hugetlb.c (BUG_ON(!hugetlb_fault_mutex_table))
>  Kernel panic - not syncing: Fatal exception
> 
> Switch to kvmalloc_objs() so the allocation falls back to vmalloc when
> the contiguous physical allocation is too large.  The table is only
> accessed by index, so virtual contiguity is sufficient.
> 
> Fixes: 8382d914ebf7 ("mm, hugetlb: improve page-fault scalability")
> Signed-off-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>

Thanks for your fix.

Acked-by: Muchun Song <muchun.song@linux.dev>

Thanks