Commit 3b6521f5 authored by Oliver O'Halloran's avatar Oliver O'Halloran Committed by Linus Torvalds
Browse files

mm/huge_memory.c: deposit a pgtable for DAX PMD faults when required 

Although all architectures use a deposited page table for THP on
anonymous VMAs, some architectures (s390 and powerpc) require the
deposited storage even for file backed VMAs due to quirks of their MMUs.

This patch adds support for depositing a table in DAX PMD fault handling
path for archs that require it.  Other architectures should see no
functional changes.

Link: http://lkml.kernel.org/r/20170411174233.21902-3-oohall@gmail.com


Signed-off-by: default avatarOliver O'Halloran <oohall@gmail.com>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: linux-nvdimm@ml01.01.org
Cc: Oliver O'Halloran <oohall@gmail.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c14a6eb4

mm/huge_memory.c

+18 −2
Original line number Diff line number Diff line
@@ -715,7 +715,8 @@ int do_huge_pmd_anonymous_page(struct vm_fault *vmf) 
}



static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,

		pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write)

		pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,

		pgtable_t pgtable)

{

	struct mm_struct *mm = vma->vm_mm;

	pmd_t entry;
@@ -729,6 +730,12 @@ static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, 
		entry = pmd_mkyoung(pmd_mkdirty(entry));

		entry = maybe_pmd_mkwrite(entry, vma);

	}



	if (pgtable) {

		pgtable_trans_huge_deposit(mm, pmd, pgtable);

		atomic_long_inc(&mm->nr_ptes);

	}



	set_pmd_at(mm, addr, pmd, entry);

	update_mmu_cache_pmd(vma, addr, pmd);

	spin_unlock(ptl);
@@ -738,6 +745,7 @@ int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, 
			pmd_t *pmd, pfn_t pfn, bool write)

{

	pgprot_t pgprot = vma->vm_page_prot;

	pgtable_t pgtable = NULL;

	/*

	 * If we had pmd_special, we could avoid all these restrictions,

	 * but we need to be consistent with PTEs and architectures that
@@ -752,9 +760,15 @@ int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, 
	if (addr < vma->vm_start || addr >= vma->vm_end)

		return VM_FAULT_SIGBUS;



	if (arch_needs_pgtable_deposit()) {

		pgtable = pte_alloc_one(vma->vm_mm, addr);

		if (!pgtable)

			return VM_FAULT_OOM;

	}



	track_pfn_insert(vma, &pgprot, pfn);



	insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write);

	insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write, pgtable);

	return VM_FAULT_NOPAGE;

}

EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
@@ -1611,6 +1625,8 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 
			tlb->fullmm);

	tlb_remove_pmd_tlb_entry(tlb, pmd, addr);

	if (vma_is_dax(vma)) {

		if (arch_needs_pgtable_deposit())

			zap_deposited_table(tlb->mm, pmd);

		spin_unlock(ptl);

		if (is_huge_zero_pmd(orig_pmd))

			tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);

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