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

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@arm.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



             reply	other threads:[~2025-09-18  9:35 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-09-18  9:34 Dev Jain [this message]
2025-09-18 10:33 ` Mike Rapoport
2025-09-18 13:06   ` Ryan Roberts
2025-09-21  7:39     ` Mike Rapoport
2025-09-22  6:02 ` Anshuman Khandual
2025-09-22  6:50   ` Dev Jain

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