Le 18/09/2026 à 10:44, Barry Song a écrit :
On Fri, Sep 18, 2026 at 2:14 PM Christophe Leroy (CS GROUP)
<[email protected]> wrote:
Le 17/09/2026 à 07:29, Wen Jiang a écrit :
From: Wen Jiang <[email protected]>
vmap installs PTE-level block mappings (SZ_16K/SZ_512K on powerpc/8xx)
by reusing set_huge_pte_at(), a HugeTLB helper gated by
CONFIG_HUGETLB_PAGE. This makes the feature silently unavailable on
CONFIG_HUGETLB_PAGE=n kernels and couples mm/vmalloc.c to HugeTLB
internals it does not otherwise need.
Add pte_set_huge() to powerpc/8xx, next to the existing
pmd_clear_huge()/pud_clear_huge() in mm/nohash/8xx.c. It builds the huge
PTE and writes it into the backing cells directly, without going through
set_huge_pte_at(), so it does not depend on CONFIG_HUGETLB_PAGE.
No pte_clear_huge() is needed: 8xx does not implement
arch_vmap_pte_range_unmap_size(), so the vmap unmap path never takes the
block-mapping branch.
In practice PPC_8xx selects HUGETLBFS unconditionally, so
CONFIG_HUGETLB_PAGE=n does not occur there today; this is a decoupling
cleanup rather than a new configuration.
8xx selects CONFIG_HUGETLB_PAGE because it uses set_huge_pte_at() to map
kernel text with large pages. That was added by commit 34536d780683
("powerpc/8xx: Add a function to early map kernel via huge pages")
But now pte_set_huge() could be used instead in
__early_map_kernel_hugepage() and then CONFIG_HUGETLB_PAGE could be removed.
Hi Christophe,
Do you mean the code below? If so, it sounds like a good place to
clean this up for powerpc as a separate cleanup patch.
Yes this is what I have in mind allthough I have not studied it in details.
diff --git a/arch/powerpc/mm/nohash/8xx.c b/arch/powerpc/mm/nohash/8xx.c
index 2518d2a6bdb4..830cdb391161 100644
--- a/arch/powerpc/mm/nohash/8xx.c
+++ b/arch/powerpc/mm/nohash/8xx.c
@@ -87,9 +87,7 @@ static int __ref
__early_map_kernel_hugepage(unsigned long va, phys_addr_t pa,
if (WARN_ON(!ptep))
return -ENOMEM;
- set_huge_pte_at(&init_mm, va, ptep,
- arch_make_huge_pte(pfn_pte(pa >> PAGE_SHIFT,
prot), shift, 0),
- 1UL << shift);
+ pte_set_huge(ptep, va, pa, prot, 1UL << shift);
return 0;
}
diff --git a/arch/powerpc/platforms/Kconfig.cputype
b/arch/powerpc/platforms/Kconfig.cputype
index f0adbf7ecb7f..efba4d960083 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -41,7 +41,6 @@ config PPC_8xx
select FSL_SOC
select PPC_KUEP
select HAVE_ARCH_VMAP_STACK
- select HUGETLBFS
config 44x
bool "AMCC 44x, 46x or 47x"
There is no caller yet: mm/vmalloc.c is converted later in this series,
once the generic fallbacks are in place.
Signed-off-by: Wen Jiang <[email protected]>
Reviewed-by: Christophe Leroy (CS GROUP) <[email protected]>
Best Regards
Barry
