Commit 6aab341e authored by Linus Torvalds's avatar Linus Torvalds
Browse files

mm: re-architect the VM_UNPAGED logic 



This replaces the (in my opinion horrible) VM_UNMAPPED logic with very
explicit support for a "remapped page range" aka VM_PFNMAP.  It allows a
VM area to contain an arbitrary range of page table entries that the VM
never touches, and never considers to be normal pages.

Any user of "remap_pfn_range()" automatically gets this new
functionality, and doesn't even have to mark the pages reserved or
indeed mark them any other way.  It just works.  As a side effect, doing
mmap() on /dev/mem works for arbitrary ranges.

Sparc update from David in the next commit.

Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 458af543

arch/powerpc/kernel/vdso.c

+2 −4
Original line number Diff line number Diff line
@@ -145,8 +145,7 @@ static void dump_vdso_pages(struct vm_area_struct * vma) 
			struct page *pg = virt_to_page(vdso32_kbase +

						       i*PAGE_SIZE);

			struct page *upg = (vma && vma->vm_mm) ?

				follow_page(vma->vm_mm, vma->vm_start +

					    i*PAGE_SIZE, 0)

				follow_page(vma, vma->vm_start + i*PAGE_SIZE, 0)

				: NULL;

			dump_one_vdso_page(pg, upg);

		}
@@ -157,8 +156,7 @@ static void dump_vdso_pages(struct vm_area_struct * vma) 
			struct page *pg = virt_to_page(vdso64_kbase +

						       i*PAGE_SIZE);

			struct page *upg = (vma && vma->vm_mm) ?

				follow_page(vma->vm_mm, vma->vm_start +

					    i*PAGE_SIZE, 0)

				follow_page(vma, vma->vm_start + i*PAGE_SIZE, 0)

				: NULL;

			dump_one_vdso_page(pg, upg);

		}

drivers/char/mem.c

+1 −1
Original line number Diff line number Diff line
@@ -591,7 +591,7 @@ static inline size_t read_zero_pagealigned(char __user * buf, size_t size) 


		if (vma->vm_start > addr || (vma->vm_flags & VM_WRITE) == 0)

			goto out_up;

		if (vma->vm_flags & (VM_SHARED | VM_HUGETLB | VM_UNPAGED))

		if (vma->vm_flags & (VM_SHARED | VM_HUGETLB))

			break;

		count = vma->vm_end - addr;

		if (count > size)

fs/proc/task_mmu.c

+3 −4
Original line number Diff line number Diff line
@@ -402,12 +402,11 @@ struct numa_maps { 
/*

 * Calculate numa node maps for a vma

 */

static struct numa_maps *get_numa_maps(const struct vm_area_struct *vma)

static struct numa_maps *get_numa_maps(struct vm_area_struct *vma)

{

	int i;

	struct page *page;

	unsigned long vaddr;

	struct mm_struct *mm = vma->vm_mm;

	int i;

	struct numa_maps *md = kmalloc(sizeof(struct numa_maps), GFP_KERNEL);



	if (!md)
@@ -420,7 +419,7 @@ static struct numa_maps *get_numa_maps(const struct vm_area_struct *vma) 
		md->node[i] =0;



 	for (vaddr = vma->vm_start; vaddr < vma->vm_end; vaddr += PAGE_SIZE) {

		page = follow_page(mm, vaddr, 0);

		page = follow_page(vma, vaddr, 0);

		if (page) {

			int count = page_mapcount(page);

include/linux/mm.h

+3 −2
Original line number Diff line number Diff line
@@ -145,7 +145,7 @@ extern unsigned int kobjsize(const void *objp); 
#define VM_GROWSDOWN	0x00000100	/* general info on the segment */

#define VM_GROWSUP	0x00000200

#define VM_SHM		0x00000000	/* Means nothing: delete it later */

#define VM_UNPAGED	0x00000400	/* Pages managed without map count */

#define VM_PFNMAP	0x00000400	/* Page-ranges managed without "struct page", just pure PFN */

#define VM_DENYWRITE	0x00000800	/* ETXTBSY on write attempts.. */



#define VM_EXECUTABLE	0x00001000
@@ -664,6 +664,7 @@ struct zap_details { 
	unsigned long truncate_count;		/* Compare vm_truncate_count */

};



struct page *vm_normal_page(struct vm_area_struct *, unsigned long, pte_t);

unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,

		unsigned long size, struct zap_details *);

unsigned long unmap_vmas(struct mmu_gather **tlb,
@@ -953,7 +954,7 @@ unsigned long vmalloc_to_pfn(void *addr); 
int remap_pfn_range(struct vm_area_struct *, unsigned long addr,

			unsigned long pfn, unsigned long size, pgprot_t);



struct page *follow_page(struct mm_struct *, unsigned long address,

struct page *follow_page(struct vm_area_struct *, unsigned long address,

			unsigned int foll_flags);

#define FOLL_WRITE	0x01	/* check pte is writable */

#define FOLL_TOUCH	0x02	/* mark page accessed */

mm/fremap.c

+7 −15
Original line number Diff line number Diff line
@@ -27,24 +27,20 @@ static int zap_pte(struct mm_struct *mm, struct vm_area_struct *vma, 
	struct page *page = NULL;



	if (pte_present(pte)) {

		unsigned long pfn = pte_pfn(pte);

		flush_cache_page(vma, addr, pfn);

		flush_cache_page(vma, addr, pte_pfn(pte));

		pte = ptep_clear_flush(vma, addr, ptep);

		if (unlikely(!pfn_valid(pfn))) {

			print_bad_pte(vma, pte, addr);

			goto out;

		}

		page = pfn_to_page(pfn);

		page = vm_normal_page(vma, addr, pte);

		if (page) {

			if (pte_dirty(pte))

				set_page_dirty(page);

			page_remove_rmap(page);

			page_cache_release(page);

		}

	} else {

		if (!pte_file(pte))

			free_swap_and_cache(pte_to_swp_entry(pte));

		pte_clear(mm, addr, ptep);

	}

out:

	return !!page;

}
@@ -65,8 +61,6 @@ int install_page(struct mm_struct *mm, struct vm_area_struct *vma, 
	pte_t pte_val;

	spinlock_t *ptl;



	BUG_ON(vma->vm_flags & VM_UNPAGED);



	pgd = pgd_offset(mm, addr);

	pud = pud_alloc(mm, pgd, addr);

	if (!pud)
@@ -122,8 +116,6 @@ int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma, 
	pte_t pte_val;

	spinlock_t *ptl;



	BUG_ON(vma->vm_flags & VM_UNPAGED);



	pgd = pgd_offset(mm, addr);

	pud = pud_alloc(mm, pgd, addr);

	if (!pud)

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