On 16.06.25 13:58, Alistair Popple wrote:
Nothing uses PFN_DEV anymore so no need to create devmap pXd's when
mapping a PFN. Instead special mappings will be created which ensures
vm_normal_page_pXd() will not return pages which don't have an
associated page. This could change behaviour slightly on architectures
where pXd_devmap() does not imply pXd_special() as the normal page
checks would have fallen through to checking VM_PFNMAP/MIXEDMAP instead,
which in theory at least could have returned a page.
However vm_normal_page_pXd() should never have been returning pages for
pXd_devmap() entries anyway, so anything relying on that would have been
a bug.
Signed-off-by: Alistair Popple <apopple@xxxxxxxxxx>
---
Changes since v1:
- New for v2
---
mm/huge_memory.c | 12 ++----------
1 file changed, 2 insertions(+), 10 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index b096240..6514e25 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1415,11 +1415,7 @@ static int insert_pmd(struct vm_area_struct *vma, unsigned long addr,
add_mm_counter(mm, mm_counter_file(fop.folio), HPAGE_PMD_NR);
} else {
entry = pmd_mkhuge(pfn_t_pmd(fop.pfn, prot));
-
- if (pfn_t_devmap(fop.pfn))
- entry = pmd_mkdevmap(entry);
- else
- entry = pmd_mkspecial(entry);
+ entry = pmd_mkspecial(entry);
}
if (write) {
entry = pmd_mkyoung(pmd_mkdirty(entry));
@@ -1565,11 +1561,7 @@ static void insert_pud(struct vm_area_struct *vma, unsigned long addr,
add_mm_counter(mm, mm_counter_file(fop.folio), HPAGE_PUD_NR);
} else {
entry = pud_mkhuge(pfn_t_pud(fop.pfn, prot));
-
- if (pfn_t_devmap(fop.pfn))
- entry = pud_mkdevmap(entry);
- else
- entry = pud_mkspecial(entry);
+ entry = pud_mkspecial(entry);
}
if (write) {
entry = pud_mkyoung(pud_mkdirty(entry));
Why not squash this patch into #3, and remove the pmd_special() check
from vm_normal_page_pmd() in the same go? Seems wrong to handle the
PMD/PUD case separately.
But now I am confused why some pte_devmap() checks are removed in patch
#3, while others are removed in #7.
Why not split it up into (a) stop setting p*_devmap() and (b) remove
p*_devmap().
Logically makes more sense to me ... :)
--
Cheers,
David / dhildenb
