Chris Wilson wrote:
> In preparation for exporting very similar functionality through another
> interface, gut the current remap_pfn_range(). The motivating factor here
> is to reuse the PGB/PUD/PMD/PTE walker, but allow back progation of
> errors rather than BUG_ON.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Rik van Riel <riel@xxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxx>
> Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxx>
> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: linux-mm@xxxxxxxxx
> ---
> mm/memory.c | 102 +++++++++++++++++++++++++++++++++---------------------------
> 1 file changed, 57 insertions(+), 45 deletions(-)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 037b812a9531..d2c7fe88a289 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2295,71 +2295,81 @@ int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
> }
> EXPORT_SYMBOL(vm_insert_mixed);
>
> +struct remap_pfn {
> + struct mm_struct *mm;
> + unsigned long addr;
> + unsigned long pfn;
> + pgprot_t prot;
> +};
> +
> /*
> * maps a range of physical memory into the requested pages. the old
> * mappings are removed. any references to nonexistent pages results
> * in null mappings (currently treated as "copy-on-access")
> */
> -static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
> - unsigned long addr, unsigned long end,
> - unsigned long pfn, pgprot_t prot)
> +static inline int remap_pfn(struct remap_pfn *r, pte_t *pte)
> +{
> + if (!pte_none(*pte))
> + return -EBUSY;
> +
> + set_pte_at(r->mm, r->addr, pte,
> + pte_mkspecial(pfn_pte(r->pfn, r->prot)));
> + r->pfn++;
> + r->addr += PAGE_SIZE;
> + return 0;
> +}
> +
> +static int remap_pte_range(struct remap_pfn *r, pmd_t *pmd, unsigned long end)
> {
> pte_t *pte;
> spinlock_t *ptl;
> + int err;
>
> - pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
> + pte = pte_alloc_map_lock(r->mm, pmd, r->addr, &ptl);
> if (!pte)
> return -ENOMEM;
> +
> arch_enter_lazy_mmu_mode();
> do {
> - BUG_ON(!pte_none(*pte));
> - set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
> - pfn++;
> - } while (pte++, addr += PAGE_SIZE, addr != end);
> + err = remap_pfn(r, pte++);
> + } while (err == 0 && r->addr < end);
> arch_leave_lazy_mmu_mode();
> +
> pte_unmap_unlock(pte - 1, ptl);
> - return 0;
> + return err;
> }
>
> -static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
> - unsigned long addr, unsigned long end,
> - unsigned long pfn, pgprot_t prot)
> +static inline int remap_pmd_range(struct remap_pfn *r, pud_t *pud, unsigned long end)
> {
> pmd_t *pmd;
> - unsigned long next;
> + int err;
>
> - pfn -= addr >> PAGE_SHIFT;
> - pmd = pmd_alloc(mm, pud, addr);
> + pmd = pmd_alloc(r->mm, pud, r->addr);
> if (!pmd)
> return -ENOMEM;
> VM_BUG_ON(pmd_trans_huge(*pmd));
> +
> do {
> - next = pmd_addr_end(addr, end);
> - if (remap_pte_range(mm, pmd, addr, next,
> - pfn + (addr >> PAGE_SHIFT), prot))
> - return -ENOMEM;
> - } while (pmd++, addr = next, addr != end);
> - return 0;
> + err = remap_pte_range(r, pmd++, pmd_addr_end(r->addr, end));
> + } while (err == 0 && r->addr < end);
> +
> + return err;
> }
>
> -static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
> - unsigned long addr, unsigned long end,
> - unsigned long pfn, pgprot_t prot)
> +static inline int remap_pud_range(struct remap_pfn *r, pgd_t *pgd, unsigned long end)
> {
> pud_t *pud;
> - unsigned long next;
> + int err;
>
> - pfn -= addr >> PAGE_SHIFT;
> - pud = pud_alloc(mm, pgd, addr);
> + pud = pud_alloc(r->mm, pgd, r->addr);
> if (!pud)
> return -ENOMEM;
> +
> do {
> - next = pud_addr_end(addr, end);
> - if (remap_pmd_range(mm, pud, addr, next,
> - pfn + (addr >> PAGE_SHIFT), prot))
> - return -ENOMEM;
> - } while (pud++, addr = next, addr != end);
> - return 0;
> + err = remap_pmd_range(r, pud++, pud_addr_end(r->addr, end));
> + } while (err == 0 && r->addr < end);
> +
> + return err;
> }
>
> /**
> @@ -2375,10 +2385,9 @@ static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
> int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
> unsigned long pfn, unsigned long size, pgprot_t prot)
> {
> - pgd_t *pgd;
> - unsigned long next;
> unsigned long end = addr + PAGE_ALIGN(size);
> - struct mm_struct *mm = vma->vm_mm;
> + struct remap_pfn r;
> + pgd_t *pgd;
> int err;
>
> /*
> @@ -2412,19 +2421,22 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
> vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
>
> BUG_ON(addr >= end);
> - pfn -= addr >> PAGE_SHIFT;
> - pgd = pgd_offset(mm, addr);
> flush_cache_range(vma, addr, end);
> +
> + r.mm = vma->vm_mm;
> + r.addr = addr;
> + r.pfn = pfn;
> + r.prot = prot;
> +
> + pgd = pgd_offset(r.mm, addr);
> do {
> - next = pgd_addr_end(addr, end);
> - err = remap_pud_range(mm, pgd, addr, next,
> - pfn + (addr >> PAGE_SHIFT), prot);
> - if (err)
> - break;
> - } while (pgd++, addr = next, addr != end);
> + err = remap_pud_range(&r, pgd++, pgd_addr_end(r.addr, end));
> + } while (err == 0 && r.addr < end);
>
> - if (err)
> + if (err) {
> untrack_pfn(vma, pfn, PAGE_ALIGN(size));
> + BUG_ON(err == -EBUSY);
We probably need a comment for the BUG_ON().
Otherwise,
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> + }
>
> return err;
> }
--
Kirill A. Shutemov
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