Commit 412d0003 authored by Dave Hansen's avatar Dave Hansen Committed by Andrew Morton
Browse files

x86/mm: use 'ptdesc' when freeing PMD pages 

There are a billion ways to refer to a physical memory address.  One of
the x86 PMD freeing code location chooses to use a 'pte_t *' to point to a
PMD page and then call a PTE-specific freeing function for it.  That's a
bit wonky.

Just use a 'struct ptdesc *' instead.  Its entire purpose is to refer to
page table pages.  It also means being able to remove an explicit cast.

Right now, pte_free_kernel() is a one-liner that calls
pagetable_dtor_free().  Effectively, all this patch does is remove one
superfluous __pa(__va(paddr)) conversion and then call
pagetable_dtor_free() directly instead of through a helper.

Link: https://lkml.kernel.org/r/20251022082635.2462433-5-baolu.lu@linux.intel.com


Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robin Murohy <robin.murphy@arm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Cc: Vasant Hegde <vasant.hegde@amd.com>
Cc: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yi Lai <yi1.lai@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 97787052

arch/x86/mm/pgtable.c

+6 −6
Original line number Diff line number Diff line
@@ -729,7 +729,7 @@ int pmd_clear_huge(pmd_t *pmd) 
int pud_free_pmd_page(pud_t *pud, unsigned long addr)

{

	pmd_t *pmd, *pmd_sv;

	pte_t *pte;

	struct ptdesc *pt;

	int i;



	pmd = pud_pgtable(*pud);
@@ -750,8 +750,8 @@ int pud_free_pmd_page(pud_t *pud, unsigned long addr) 


	for (i = 0; i < PTRS_PER_PMD; i++) {

		if (!pmd_none(pmd_sv[i])) {

			pte = (pte_t *)pmd_page_vaddr(pmd_sv[i]);

			pte_free_kernel(&init_mm, pte);

			pt = page_ptdesc(pmd_page(pmd_sv[i]));

			pagetable_dtor_free(pt);

		}

	}
@@ -772,15 +772,15 @@ int pud_free_pmd_page(pud_t *pud, unsigned long addr) 
 */

int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)

{

	pte_t *pte;

	struct ptdesc *pt;



	pte = (pte_t *)pmd_page_vaddr(*pmd);

	pt = page_ptdesc(pmd_page(*pmd));

	pmd_clear(pmd);



	/* INVLPG to clear all paging-structure caches */

	flush_tlb_kernel_range(addr, addr + PAGE_SIZE-1);



	pte_free_kernel(&init_mm, pte);

	pagetable_dtor_free(pt);



	return 1;

}