This is a note to let you know that I've just added the patch titled
arm64/mm: Ensure adequate HUGE_MAX_HSTATE
to the 6.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm64-mm-ensure-adequate-huge_max_hstate.patch
and it can be found in the queue-6.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 96a6dec94bd0151da2aced144f57e00f26e95900
Author: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Date: Mon Dec 2 12:14:07 2024 +0530
arm64/mm: Ensure adequate HUGE_MAX_HSTATE
[ Upstream commit 1e5823c8e86de83a43d59a522b4de29066d3b306 ]
This asserts that HUGE_MAX_HSTATE is sufficient enough preventing potential
hugetlb_max_hstate runtime overflow in hugetlb_add_hstate() thus triggering
a BUG_ON() there after.
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Reviewed-by: Ryan Roberts <ryan.roberts@xxxxxxx>
Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20241202064407.53807-1-anshuman.khandual@xxxxxxx
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index 5f1e2103888b7..0a6956bbfb326 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -508,6 +508,18 @@ pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
static int __init hugetlbpage_init(void)
{
+ /*
+ * HugeTLB pages are supported on maximum four page table
+ * levels (PUD, CONT PMD, PMD, CONT PTE) for a given base
+ * page size, corresponding to hugetlb_add_hstate() calls
+ * here.
+ *
+ * HUGE_MAX_HSTATE should at least match maximum supported
+ * HugeTLB page sizes on the platform. Any new addition to
+ * supported HugeTLB page sizes will also require changing
+ * HUGE_MAX_HSTATE as well.
+ */
+ BUILD_BUG_ON(HUGE_MAX_HSTATE < 4);
if (pud_sect_supported())
hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
