[PATCH 3/4] mm: hugetlb: skip CMA when direct reclaim is disallowed

[Qi Zheng]

From: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>

Switching HugeTLB CMA allocation from cma_alloc_folio() to
cma_alloc_frozen_compound() stopped forwarding the caller's GFP mask.
The new helper uses GFP_KERNEL, re-enabling direct reclaim even when
the caller explicitly disabled it.

The first MPOL_PREFERRED_MANY allocation attempt clears
__GFP_DIRECT_RECLAIM to try the preferred nodes before falling back to
other nodes. For gigantic surplus pages, the CMA path can therefore
enter direct reclaim while allocating migration targets during this
attempt.

Skip HugeTLB CMA allocation when direct reclaim is disallowed.

Fixes: 9bda131c6093 ("mm: cma: add cma_alloc_frozen{_compound}()")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
---
 mm/hugetlb_cma.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/hugetlb_cma.c b/mm/hugetlb_cma.c
index dde1c866406fb..90f8d718a1f16 100644
--- a/mm/hugetlb_cma.c
+++ b/mm/hugetlb_cma.c
@@ -59,7 +59,7 @@ struct folio *hugetlb_cma_alloc_frozen_folio(int order, gfp_t gfp_mask,
 	const nodemask_t *nmask;
 	unsigned int cpuset_mems_cookie;
 
-	if (!hugetlb_cma_size)
+	if (!hugetlb_cma_size || !gfpflags_allow_blocking(gfp_mask))
 		return NULL;
 
 	if (current->flags & PF_MEMALLOC_PIN)
-- 
2.54.0