Re: [PATCH 2/4] mm: hugetlb: skip CMA allocations under PF_MEMALLOC_PIN

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

> On Nov 3, 2026, at 16:01, Qi Zheng <qi.zheng@linux.dev> wrote:
> 
> From: Qi Zheng <zhengqi.arch@bytedance.com>
> 
> With gigantic overcommit enabled, a fault during long-term pinning
> can allocate a fresh HugeTLB folio from CMA despite PF_MEMALLOC_PIN.
> 
> The folio must then be migrated before it can be pinned. However,
> fresh gigantic migration targets are not supported, so pinning fails
> when the HugeTLB pool has no suitable target, even if the original
> fault could have allocated pinnable memory outside CMA.
> 
> Honor PF_MEMALLOC_PIN in the HugeTLB CMA allocator so the fault can
> try the non-CMA fallback, or fail when allocation is restricted to CMA.
> 
> Fixes: eb02f14c4a2b ("mm/hugetlb: allow overcommitting gigantic hugepages")
> Cc: stable@vger.kernel.org
> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>

LGTM.

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

Thanks.