linux-kernel - [PATCH] mm: Remove PMD alignment constraint in execmem

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Message-Id: <20250918093453.75676-1-dev.jain@arm.com>
Date: Thu, 18 Sep 2025 15:04:53 +0530
From: Dev Jain <dev.jain@....com>
To: akpm@...ux-foundation.org
Cc: rppt@...nel.org,
	ryan.roberts@....com,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Dev Jain <dev.jain@....com>
Subject: [PATCH] mm: Remove PMD alignment constraint in execmem_vmalloc()

When using vmalloc with VM_ALLOW_HUGE_VMAP flag, it will set the alignment
to PMD_SIZE internally, if it deems huge mappings to be eligible.
Therefore, setting the alignment in execmem_vmalloc is redundant. Apart
from this, it also reduces the probability of allocation in case vmalloc
fails to allocate hugepages - in the fallback case, vmalloc tries to use
the original alignment and allocate basepages, which unfortunately will
again be PMD_SIZE passed over from execmem_vmalloc, thus constraining
the search for a free space in vmalloc region.

Therefore, remove this constraint.

Signed-off-by: Dev Jain <dev.jain@....com>
---
mm-selftests pass, but I am not sure if they touch execmem code, and I
have no experience with this code.

 mm/execmem.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/mm/execmem.c b/mm/execmem.c
index 0822305413ec..810a4ba9c924 100644
--- a/mm/execmem.c
+++ b/mm/execmem.c
@@ -38,9 +38,6 @@ static void *execmem_vmalloc(struct execmem_range *range, size_t size,
 	if (kasan)
 		vm_flags |= VM_DEFER_KMEMLEAK;

-	if (vm_flags & VM_ALLOW_HUGE_VMAP)
-		align = PMD_SIZE;
-
 	p = __vmalloc_node_range(size, align, start, end, gfp_flags,
 				 pgprot, vm_flags, NUMA_NO_NODE,
 				 __builtin_return_address(0));
-- 
2.30.2