Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 426 insertions, 0 deletions

diff --git a/mm/mremap.c b/mm/mremap.c
new file mode 100644
index 000000000000..0d1c1b9c7a0a
--- /dev/null
+++ b/mm/mremap.c
@@ -0,0 +1,426 @@
+/*
+ *      mm/mremap.c
+ *
+ *      (C) Copyright 1996 Linus Torvalds
+ *
+ *      Address space accounting code   <alan@redhat.com>
+ *      (C) Copyright 2002 Red Hat Inc, All Rights Reserved
+ */
+
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+#include <linux/slab.h>
+#include <linux/shm.h>
+#include <linux/mman.h>
+#include <linux/swap.h>
+#include <linux/fs.h>
+#include <linux/highmem.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
+
+#include <asm/uaccess.h>
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+
+static pte_t *get_one_pte_map_nested(struct mm_struct *mm, unsigned long addr)
+{
+        pgd_t *pgd;
+        pud_t *pud;
+        pmd_t *pmd;
+        pte_t *pte = NULL;
+
+        pgd = pgd_offset(mm, addr);
+        if (pgd_none_or_clear_bad(pgd))
+                goto end;
+
+        pud = pud_offset(pgd, addr);
+        if (pud_none_or_clear_bad(pud))
+                goto end;
+
+        pmd = pmd_offset(pud, addr);
+        if (pmd_none_or_clear_bad(pmd))
+                goto end;
+
+        pte = pte_offset_map_nested(pmd, addr);
+        if (pte_none(*pte)) {
+                pte_unmap_nested(pte);
+                pte = NULL;
+        }
+end:
+        return pte;
+}
+
+static pte_t *get_one_pte_map(struct mm_struct *mm, unsigned long addr)
+{
+        pgd_t *pgd;
+        pud_t *pud;
+        pmd_t *pmd;
+
+        pgd = pgd_offset(mm, addr);
+        if (pgd_none_or_clear_bad(pgd))
+                return NULL;
+
+        pud = pud_offset(pgd, addr);
+        if (pud_none_or_clear_bad(pud))
+                return NULL;
+
+        pmd = pmd_offset(pud, addr);
+        if (pmd_none_or_clear_bad(pmd))
+                return NULL;
+
+        return pte_offset_map(pmd, addr);
+}
+
+static inline pte_t *alloc_one_pte_map(struct mm_struct *mm, unsigned long addr)
+{
+        pgd_t *pgd;
+        pud_t *pud;
+        pmd_t *pmd;
+        pte_t *pte = NULL;
+
+        pgd = pgd_offset(mm, addr);
+
+        pud = pud_alloc(mm, pgd, addr);
+        if (!pud)
+                return NULL;
+        pmd = pmd_alloc(mm, pud, addr);
+        if (pmd)
+                pte = pte_alloc_map(mm, pmd, addr);
+        return pte;
+}
+
+static int
+move_one_page(struct vm_area_struct *vma, unsigned long old_addr,
+                struct vm_area_struct *new_vma, unsigned long new_addr)
+{
+        struct address_space *mapping = NULL;
+        struct mm_struct *mm = vma->vm_mm;
+        int error = 0;
+        pte_t *src, *dst;
+
+        if (vma->vm_file) {
+                /*
+                 * Subtle point from Rajesh Venkatasubramanian: before
+                 * moving file-based ptes, we must lock vmtruncate out,
+                 * since it might clean the dst vma before the src vma,
+                 * and we propagate stale pages into the dst afterward.
+                 */
+                mapping = vma->vm_file->f_mapping;
+                spin_lock(&mapping->i_mmap_lock);
+                if (new_vma->vm_truncate_count &&
+                    new_vma->vm_truncate_count != vma->vm_truncate_count)
+                        new_vma->vm_truncate_count = 0;
+        }
+        spin_lock(&mm->page_table_lock);
+
+        src = get_one_pte_map_nested(mm, old_addr);
+        if (src) {
+                /*
+                 * Look to see whether alloc_one_pte_map needs to perform a
+                 * memory allocation.  If it does then we need to drop the
+                 * atomic kmap
+                 */
+                dst = get_one_pte_map(mm, new_addr);
+                if (unlikely(!dst)) {
+                        pte_unmap_nested(src);
+                        if (mapping)
+                                spin_unlock(&mapping->i_mmap_lock);
+                        dst = alloc_one_pte_map(mm, new_addr);
+                        if (mapping && !spin_trylock(&mapping->i_mmap_lock)) {
+                                spin_unlock(&mm->page_table_lock);
+                                spin_lock(&mapping->i_mmap_lock);
+                                spin_lock(&mm->page_table_lock);
+                        }
+                        src = get_one_pte_map_nested(mm, old_addr);
+                }
+                /*
+                 * Since alloc_one_pte_map can drop and re-acquire
+                 * page_table_lock, we should re-check the src entry...
+                 */
+                if (src) {
+                        if (dst) {
+                                pte_t pte;
+                                pte = ptep_clear_flush(vma, old_addr, src);
+                                set_pte_at(mm, new_addr, dst, pte);
+                        } else
+                                error = -ENOMEM;
+                        pte_unmap_nested(src);
+                }
+                if (dst)
+                        pte_unmap(dst);
+        }
+        spin_unlock(&mm->page_table_lock);
+        if (mapping)
+                spin_unlock(&mapping->i_mmap_lock);
+        return error;
+}
+
+static unsigned long move_page_tables(struct vm_area_struct *vma,
+                unsigned long old_addr, struct vm_area_struct *new_vma,
+                unsigned long new_addr, unsigned long len)
+{
+        unsigned long offset;
+
+        flush_cache_range(vma, old_addr, old_addr + len);
+
+        /*
+         * This is not the clever way to do this, but we're taking the
+         * easy way out on the assumption that most remappings will be
+         * only a few pages.. This also makes error recovery easier.
+         */
+        for (offset = 0; offset < len; offset += PAGE_SIZE) {
+                if (move_one_page(vma, old_addr + offset,
+                                new_vma, new_addr + offset) < 0)
+                        break;
+                cond_resched();
+        }
+        return offset;
+}
+
+static unsigned long move_vma(struct vm_area_struct *vma,
+                unsigned long old_addr, unsigned long old_len,
+                unsigned long new_len, unsigned long new_addr)
+{
+        struct mm_struct *mm = vma->vm_mm;
+        struct vm_area_struct *new_vma;
+        unsigned long vm_flags = vma->vm_flags;
+        unsigned long new_pgoff;
+        unsigned long moved_len;
+        unsigned long excess = 0;
+        int split = 0;
+
+        /*
+         * We'd prefer to avoid failure later on in do_munmap:
+         * which may split one vma into three before unmapping.
+         */
+        if (mm->map_count >= sysctl_max_map_count - 3)
+                return -ENOMEM;
+
+        new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
+        new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff);
+        if (!new_vma)
+                return -ENOMEM;
+
+        moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len);
+        if (moved_len < old_len) {
+                /*
+                 * On error, move entries back from new area to old,
+                 * which will succeed since page tables still there,
+                 * and then proceed to unmap new area instead of old.
+                 */
+                move_page_tables(new_vma, new_addr, vma, old_addr, moved_len);
+                vma = new_vma;
+                old_len = new_len;
+                old_addr = new_addr;
+                new_addr = -ENOMEM;
+        }
+
+        /* Conceal VM_ACCOUNT so old reservation is not undone */
+        if (vm_flags & VM_ACCOUNT) {
+                vma->vm_flags &= ~VM_ACCOUNT;
+                excess = vma->vm_end - vma->vm_start - old_len;
+                if (old_addr > vma->vm_start &&
+                    old_addr + old_len < vma->vm_end)
+                        split = 1;
+        }
+
+        if (do_munmap(mm, old_addr, old_len) < 0) {
+                /* OOM: unable to split vma, just get accounts right */
+                vm_unacct_memory(excess >> PAGE_SHIFT);
+                excess = 0;
+        }
+
+        /* Restore VM_ACCOUNT if one or two pieces of vma left */
+        if (excess) {
+                vma->vm_flags |= VM_ACCOUNT;
+                if (split)
+                        vma->vm_next->vm_flags |= VM_ACCOUNT;
+        }
+
+        mm->total_vm += new_len >> PAGE_SHIFT;
+        __vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
+        if (vm_flags & VM_LOCKED) {
+                mm->locked_vm += new_len >> PAGE_SHIFT;
+                if (new_len > old_len)
+                        make_pages_present(new_addr + old_len,
+                                           new_addr + new_len);
+        }
+
+        return new_addr;
+}
+
+/*
+ * Expand (or shrink) an existing mapping, potentially moving it at the
+ * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
+ *
+ * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
+ * This option implies MREMAP_MAYMOVE.
+ */
+unsigned long do_mremap(unsigned long addr,
+        unsigned long old_len, unsigned long new_len,
+        unsigned long flags, unsigned long new_addr)
+{
+        struct vm_area_struct *vma;
+        unsigned long ret = -EINVAL;
+        unsigned long charged = 0;
+
+        if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
+                goto out;
+
+        if (addr & ~PAGE_MASK)
+                goto out;
+
+        old_len = PAGE_ALIGN(old_len);
+        new_len = PAGE_ALIGN(new_len);
+
+        /*
+         * We allow a zero old-len as a special case
+         * for DOS-emu "duplicate shm area" thing. But
+         * a zero new-len is nonsensical.
+         */
+        if (!new_len)
+                goto out;
+
+        /* new_addr is only valid if MREMAP_FIXED is specified */
+        if (flags & MREMAP_FIXED) {
+                if (new_addr & ~PAGE_MASK)
+                        goto out;
+                if (!(flags & MREMAP_MAYMOVE))
+                        goto out;
+
+                if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
+                        goto out;
+
+                /* Check if the location we're moving into overlaps the
+                 * old location at all, and fail if it does.
+                 */
+                if ((new_addr <= addr) && (new_addr+new_len) > addr)
+                        goto out;
+
+                if ((addr <= new_addr) && (addr+old_len) > new_addr)
+                        goto out;
+
+                ret = do_munmap(current->mm, new_addr, new_len);
+                if (ret)
+                        goto out;
+        }
+
+        /*
+         * Always allow a shrinking remap: that just unmaps
+         * the unnecessary pages..
+         * do_munmap does all the needed commit accounting
+         */
+        if (old_len >= new_len) {
+                ret = do_munmap(current->mm, addr+new_len, old_len - new_len);
+                if (ret && old_len != new_len)
+                        goto out;
+                ret = addr;
+                if (!(flags & MREMAP_FIXED) || (new_addr == addr))
+                        goto out;
+                old_len = new_len;
+        }
+
+        /*
+         * Ok, we need to grow..  or relocate.
+         */
+        ret = -EFAULT;
+        vma = find_vma(current->mm, addr);
+        if (!vma || vma->vm_start > addr)
+                goto out;
+        if (is_vm_hugetlb_page(vma)) {
+                ret = -EINVAL;
+                goto out;
+        }
+        /* We can't remap across vm area boundaries */
+        if (old_len > vma->vm_end - addr)
+                goto out;
+        if (vma->vm_flags & VM_DONTEXPAND) {
+                if (new_len > old_len)
+                        goto out;
+        }
+        if (vma->vm_flags & VM_LOCKED) {
+                unsigned long locked, lock_limit;
+                locked = current->mm->locked_vm << PAGE_SHIFT;
+                lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
+                locked += new_len - old_len;
+                ret = -EAGAIN;
+                if (locked > lock_limit && !capable(CAP_IPC_LOCK))
+                        goto out;
+        }
+        ret = -ENOMEM;
+        if ((current->mm->total_vm << PAGE_SHIFT) + (new_len - old_len)
+            > current->signal->rlim[RLIMIT_AS].rlim_cur)
+                goto out;
+
+        if (vma->vm_flags & VM_ACCOUNT) {
+                charged = (new_len - old_len) >> PAGE_SHIFT;
+                if (security_vm_enough_memory(charged))
+                        goto out_nc;
+        }
+
+        /* old_len exactly to the end of the area..
+         * And we're not relocating the area.
+         */
+        if (old_len == vma->vm_end - addr &&
+            !((flags & MREMAP_FIXED) && (addr != new_addr)) &&
+            (old_len != new_len || !(flags & MREMAP_MAYMOVE))) {
+                unsigned long max_addr = TASK_SIZE;
+                if (vma->vm_next)
+                        max_addr = vma->vm_next->vm_start;
+                /* can we just expand the current mapping? */
+                if (max_addr - addr >= new_len) {
+                        int pages = (new_len - old_len) >> PAGE_SHIFT;
+
+                        vma_adjust(vma, vma->vm_start,
+                                addr + new_len, vma->vm_pgoff, NULL);
+
+                        current->mm->total_vm += pages;
+                        __vm_stat_account(vma->vm_mm, vma->vm_flags,
+                                                        vma->vm_file, pages);
+                        if (vma->vm_flags & VM_LOCKED) {
+                                current->mm->locked_vm += pages;
+                                make_pages_present(addr + old_len,
+                                                   addr + new_len);
+                        }
+                        ret = addr;
+                        goto out;
+                }
+        }
+
+        /*
+         * We weren't able to just expand or shrink the area,
+         * we need to create a new one and move it..
+         */
+        ret = -ENOMEM;
+        if (flags & MREMAP_MAYMOVE) {
+                if (!(flags & MREMAP_FIXED)) {
+                        unsigned long map_flags = 0;
+                        if (vma->vm_flags & VM_MAYSHARE)
+                                map_flags |= MAP_SHARED;
+
+                        new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
+                                                vma->vm_pgoff, map_flags);
+                        ret = new_addr;
+                        if (new_addr & ~PAGE_MASK)
+                                goto out;
+                }
+                ret = move_vma(vma, addr, old_len, new_len, new_addr);
+        }
+out:
+        if (ret & ~PAGE_MASK)
+                vm_unacct_memory(charged);
+out_nc:
+        return ret;
+}
+
+asmlinkage unsigned long sys_mremap(unsigned long addr,
+        unsigned long old_len, unsigned long new_len,
+        unsigned long flags, unsigned long new_addr)
+{
+        unsigned long ret;
+
+        down_write(&current->mm->mmap_sem);
+        ret = do_mremap(addr, old_len, new_len, flags, new_addr);
+        up_write(&current->mm->mmap_sem);
+        return ret;
+}