linux-IllusionX/mm/fremap.c
Rik van Riel ba470de431 mmap: handle mlocked pages during map, remap, unmap
Originally by Nick Piggin <npiggin@suse.de>

Remove mlocked pages from the LRU using "unevictable infrastructure"
during mmap(), munmap(), mremap() and truncate().  Try to move back to
normal LRU lists on munmap() when last mlocked mapping removed.  Remove
PageMlocked() status when page truncated from file.

[akpm@linux-foundation.org: cleanup]
[kamezawa.hiroyu@jp.fujitsu.com: fix double unlock_page()]
[kosaki.motohiro@jp.fujitsu.com: split LRU: munlock rework]
[lee.schermerhorn@hp.com: mlock: fix __mlock_vma_pages_range comment block]
[akpm@linux-foundation.org: remove bogus kerneldoc token]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamewzawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-20 08:52:31 -07:00

260 lines
6.7 KiB
C

/*
* linux/mm/fremap.c
*
* Explicit pagetable population and nonlinear (random) mappings support.
*
* started by Ingo Molnar, Copyright (C) 2002, 2003
*/
#include <linux/backing-dev.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/file.h>
#include <linux/mman.h>
#include <linux/pagemap.h>
#include <linux/swapops.h>
#include <linux/rmap.h>
#include <linux/module.h>
#include <linux/syscalls.h>
#include <linux/mmu_notifier.h>
#include <asm/mmu_context.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include "internal.h"
static void zap_pte(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep)
{
pte_t pte = *ptep;
if (pte_present(pte)) {
struct page *page;
flush_cache_page(vma, addr, pte_pfn(pte));
pte = ptep_clear_flush(vma, addr, ptep);
page = vm_normal_page(vma, addr, pte);
if (page) {
if (pte_dirty(pte))
set_page_dirty(page);
page_remove_rmap(page, vma);
page_cache_release(page);
update_hiwater_rss(mm);
dec_mm_counter(mm, file_rss);
}
} else {
if (!pte_file(pte))
free_swap_and_cache(pte_to_swp_entry(pte));
pte_clear_not_present_full(mm, addr, ptep, 0);
}
}
/*
* Install a file pte to a given virtual memory address, release any
* previously existing mapping.
*/
static int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, unsigned long pgoff, pgprot_t prot)
{
int err = -ENOMEM;
pte_t *pte;
spinlock_t *ptl;
pte = get_locked_pte(mm, addr, &ptl);
if (!pte)
goto out;
if (!pte_none(*pte))
zap_pte(mm, vma, addr, pte);
set_pte_at(mm, addr, pte, pgoff_to_pte(pgoff));
/*
* We don't need to run update_mmu_cache() here because the "file pte"
* being installed by install_file_pte() is not a real pte - it's a
* non-present entry (like a swap entry), noting what file offset should
* be mapped there when there's a fault (in a non-linear vma where
* that's not obvious).
*/
pte_unmap_unlock(pte, ptl);
err = 0;
out:
return err;
}
static int populate_range(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, unsigned long size, pgoff_t pgoff)
{
int err;
do {
err = install_file_pte(mm, vma, addr, pgoff, vma->vm_page_prot);
if (err)
return err;
size -= PAGE_SIZE;
addr += PAGE_SIZE;
pgoff++;
} while (size);
return 0;
}
/**
* sys_remap_file_pages - remap arbitrary pages of an existing VM_SHARED vma
* @start: start of the remapped virtual memory range
* @size: size of the remapped virtual memory range
* @prot: new protection bits of the range (see NOTE)
* @pgoff: to-be-mapped page of the backing store file
* @flags: 0 or MAP_NONBLOCKED - the later will cause no IO.
*
* sys_remap_file_pages remaps arbitrary pages of an existing VM_SHARED vma
* (shared backing store file).
*
* This syscall works purely via pagetables, so it's the most efficient
* way to map the same (large) file into a given virtual window. Unlike
* mmap()/mremap() it does not create any new vmas. The new mappings are
* also safe across swapout.
*
* NOTE: the @prot parameter right now is ignored (but must be zero),
* and the vma's default protection is used. Arbitrary protections
* might be implemented in the future.
*/
asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size,
unsigned long prot, unsigned long pgoff, unsigned long flags)
{
struct mm_struct *mm = current->mm;
struct address_space *mapping;
unsigned long end = start + size;
struct vm_area_struct *vma;
int err = -EINVAL;
int has_write_lock = 0;
if (prot)
return err;
/*
* Sanitize the syscall parameters:
*/
start = start & PAGE_MASK;
size = size & PAGE_MASK;
/* Does the address range wrap, or is the span zero-sized? */
if (start + size <= start)
return err;
/* Can we represent this offset inside this architecture's pte's? */
#if PTE_FILE_MAX_BITS < BITS_PER_LONG
if (pgoff + (size >> PAGE_SHIFT) >= (1UL << PTE_FILE_MAX_BITS))
return err;
#endif
/* We need down_write() to change vma->vm_flags. */
down_read(&mm->mmap_sem);
retry:
vma = find_vma(mm, start);
/*
* Make sure the vma is shared, that it supports prefaulting,
* and that the remapped range is valid and fully within
* the single existing vma. vm_private_data is used as a
* swapout cursor in a VM_NONLINEAR vma.
*/
if (!vma || !(vma->vm_flags & VM_SHARED))
goto out;
if (vma->vm_private_data && !(vma->vm_flags & VM_NONLINEAR))
goto out;
if (!(vma->vm_flags & VM_CAN_NONLINEAR))
goto out;
if (end <= start || start < vma->vm_start || end > vma->vm_end)
goto out;
/* Must set VM_NONLINEAR before any pages are populated. */
if (!(vma->vm_flags & VM_NONLINEAR)) {
/* Don't need a nonlinear mapping, exit success */
if (pgoff == linear_page_index(vma, start)) {
err = 0;
goto out;
}
if (!has_write_lock) {
up_read(&mm->mmap_sem);
down_write(&mm->mmap_sem);
has_write_lock = 1;
goto retry;
}
mapping = vma->vm_file->f_mapping;
/*
* page_mkclean doesn't work on nonlinear vmas, so if
* dirty pages need to be accounted, emulate with linear
* vmas.
*/
if (mapping_cap_account_dirty(mapping)) {
unsigned long addr;
struct file *file = vma->vm_file;
flags &= MAP_NONBLOCK;
get_file(file);
addr = mmap_region(file, start, size,
flags, vma->vm_flags, pgoff, 1);
fput(file);
if (IS_ERR_VALUE(addr)) {
err = addr;
} else {
BUG_ON(addr != start);
err = 0;
}
goto out;
}
spin_lock(&mapping->i_mmap_lock);
flush_dcache_mmap_lock(mapping);
vma->vm_flags |= VM_NONLINEAR;
vma_prio_tree_remove(vma, &mapping->i_mmap);
vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
flush_dcache_mmap_unlock(mapping);
spin_unlock(&mapping->i_mmap_lock);
}
if (vma->vm_flags & VM_LOCKED) {
/*
* drop PG_Mlocked flag for over-mapped range
*/
unsigned int saved_flags = vma->vm_flags;
munlock_vma_pages_range(vma, start, start + size);
vma->vm_flags = saved_flags;
}
mmu_notifier_invalidate_range_start(mm, start, start + size);
err = populate_range(mm, vma, start, size, pgoff);
mmu_notifier_invalidate_range_end(mm, start, start + size);
if (!err && !(flags & MAP_NONBLOCK)) {
if (vma->vm_flags & VM_LOCKED) {
/*
* might be mapping previously unmapped range of file
*/
mlock_vma_pages_range(vma, start, start + size);
} else {
if (unlikely(has_write_lock)) {
downgrade_write(&mm->mmap_sem);
has_write_lock = 0;
}
make_pages_present(start, start+size);
}
}
/*
* We can't clear VM_NONLINEAR because we'd have to do
* it after ->populate completes, and that would prevent
* downgrading the lock. (Locks can't be upgraded).
*/
out:
if (likely(!has_write_lock))
up_read(&mm->mmap_sem);
else
up_write(&mm->mmap_sem);
return err;
}