diff options
| -rw-r--r-- | mm/mmap.c | 50 |
1 files changed, 46 insertions, 4 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index 43c4955535a..da3e9c04bf3 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -6,6 +6,7 @@ * Address space accounting code <alan@lxorguk.ukuu.org.uk> */ +#include <linux/kernel.h> #include <linux/slab.h> #include <linux/backing-dev.h> #include <linux/mm.h> @@ -550,6 +551,34 @@ static int find_vma_links(struct mm_struct *mm, unsigned long addr, return 0; } +static unsigned long count_vma_pages_range(struct mm_struct *mm, + unsigned long addr, unsigned long end) +{ + unsigned long nr_pages = 0; + struct vm_area_struct *vma; + + /* Find first overlaping mapping */ + vma = find_vma_intersection(mm, addr, end); + if (!vma) + return 0; + + nr_pages = (min(end, vma->vm_end) - + max(addr, vma->vm_start)) >> PAGE_SHIFT; + + /* Iterate over the rest of the overlaps */ + for (vma = vma->vm_next; vma; vma = vma->vm_next) { + unsigned long overlap_len; + + if (vma->vm_start > end) + break; + + overlap_len = min(end, vma->vm_end) - vma->vm_start; + nr_pages += overlap_len >> PAGE_SHIFT; + } + + return nr_pages; +} + void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, struct rb_node **rb_link, struct rb_node *rb_parent) { @@ -1442,6 +1471,23 @@ unsigned long mmap_region(struct file *file, unsigned long addr, unsigned long charged = 0; struct inode *inode = file ? file_inode(file) : NULL; + /* Check against address space limit. */ + if (!may_expand_vm(mm, len >> PAGE_SHIFT)) { + unsigned long nr_pages; + + /* + * MAP_FIXED may remove pages of mappings that intersects with + * requested mapping. Account for the pages it would unmap. + */ + if (!(vm_flags & MAP_FIXED)) + return -ENOMEM; + + nr_pages = count_vma_pages_range(mm, addr, addr + len); + + if (!may_expand_vm(mm, (len >> PAGE_SHIFT) - nr_pages)) + return -ENOMEM; + } + /* Clear old maps */ error = -ENOMEM; munmap_back: @@ -1451,10 +1497,6 @@ munmap_back: goto munmap_back; } - /* Check against address space limit. */ - if (!may_expand_vm(mm, len >> PAGE_SHIFT)) - return -ENOMEM; - /* * Private writable mapping: check memory availability */ |