Re: [PATCH 07/12] mm: Remove redundant pXd_devmap calls
From: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Date: 2025-05-29 11:54:40
Also in:
dri-devel, linux-arm-kernel, linux-cxl, linux-ext4, linux-fsdevel, linux-mm, linux-riscv, linux-xfs, lkml, loongarch, nvdimm
On Thu, 29 May 2025 16:32:08 +1000 Alistair Popple [off-list ref] wrote:
DAX was the only thing that created pmd_devmap and pud_devmap entries however it no longer does as DAX pages are now refcounted normally and pXd_trans_huge() returns true for those. Therefore checking both pXd_devmap and pXd_trans_huge() is redundant and the former can be removed without changing behaviour as it will always be false. Signed-off-by: Alistair Popple <apopple@nvidia.com>
quoted hunk ↗ jump to hunk
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 8d9d706..31b4110 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c@@ -1398,10 +1398,7 @@ static int insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, } entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); - if (pfn_t_devmap(pfn))
Didn't this go away in patch 5? I didn't check but this looks like a bisectability issue.
- entry = pmd_mkdevmap(entry);
- else
- entry = pmd_mkspecial(entry);
+ entry = pmd_mkspecial(entry);
if (write) {
entry = pmd_mkyoung(pmd_mkdirty(entry));
entry = maybe_pmd_mkwrite(entry, vma);