diff options
Diffstat (limited to 'mm/mmap.c')
| -rw-r--r-- | mm/mmap.c | 80 |
1 files changed, 67 insertions, 13 deletions
@@ -67,7 +67,7 @@ int vm_enough_memory(long pages) } /* Remove one vm structure from the inode's i_mapping address space. */ -static inline void remove_shared_vm_struct(struct vm_area_struct *vma) +static inline void __remove_shared_vm_struct(struct vm_area_struct *vma) { struct file * file = vma->vm_file; @@ -75,14 +75,41 @@ static inline void remove_shared_vm_struct(struct vm_area_struct *vma) struct inode *inode = file->f_dentry->d_inode; if (vma->vm_flags & VM_DENYWRITE) atomic_inc(&inode->i_writecount); - spin_lock(&inode->i_mapping->i_shared_lock); if(vma->vm_next_share) vma->vm_next_share->vm_pprev_share = vma->vm_pprev_share; *vma->vm_pprev_share = vma->vm_next_share; - spin_unlock(&inode->i_mapping->i_shared_lock); } } +static inline void remove_shared_vm_struct(struct vm_area_struct *vma) +{ + lock_vma_mappings(vma); + __remove_shared_vm_struct(vma); + unlock_vma_mappings(vma); +} + +void lock_vma_mappings(struct vm_area_struct *vma) +{ + struct address_space *mapping; + + mapping = NULL; + if (vma->vm_file) + mapping = vma->vm_file->f_dentry->d_inode->i_mapping; + if (mapping) + spin_lock(&mapping->i_shared_lock); +} + +void unlock_vma_mappings(struct vm_area_struct *vma) +{ + struct address_space *mapping; + + mapping = NULL; + if (vma->vm_file) + mapping = vma->vm_file->f_dentry->d_inode->i_mapping; + if (mapping) + spin_unlock(&mapping->i_shared_lock); +} + /* * sys_brk() for the most part doesn't need the global kernel * lock, except when an application is doing something nasty @@ -316,13 +343,22 @@ unsigned long do_mmap_pgoff(struct file * file, unsigned long addr, unsigned lon * after the call. Save the values we need now ... */ flags = vma->vm_flags; - addr = vma->vm_start; /* can addr have changed?? */ + + /* Can addr have changed?? + * + * Answer: Yes, several device drivers can do it in their + * f_op->mmap method. -DaveM + */ + addr = vma->vm_start; + + lock_vma_mappings(vma); spin_lock(&mm->page_table_lock); - insert_vm_struct(mm, vma); + __insert_vm_struct(mm, vma); if (correct_wcount) atomic_inc(&file->f_dentry->d_inode->i_writecount); merge_segments(mm, vma->vm_start, vma->vm_end); spin_unlock(&mm->page_table_lock); + unlock_vma_mappings(vma); mm->total_vm += len >> PAGE_SHIFT; if (flags & VM_LOCKED) { @@ -534,10 +570,12 @@ static struct vm_area_struct * unmap_fixup(struct mm_struct *mm, /* Work out to one of the ends. */ if (end == area->vm_end) { area->vm_end = addr; + lock_vma_mappings(area); spin_lock(&mm->page_table_lock); } else if (addr == area->vm_start) { area->vm_pgoff += (end - area->vm_start) >> PAGE_SHIFT; area->vm_start = end; + lock_vma_mappings(area); spin_lock(&mm->page_table_lock); } else { /* Unmapping a hole: area->vm_start < addr <= end < area->vm_end */ @@ -560,12 +598,18 @@ static struct vm_area_struct * unmap_fixup(struct mm_struct *mm, if (mpnt->vm_ops && mpnt->vm_ops->open) mpnt->vm_ops->open(mpnt); area->vm_end = addr; /* Truncate area */ + + /* Because mpnt->vm_file == area->vm_file this locks + * things correctly. + */ + lock_vma_mappings(area); spin_lock(&mm->page_table_lock); - insert_vm_struct(mm, mpnt); + __insert_vm_struct(mm, mpnt); } - insert_vm_struct(mm, area); + __insert_vm_struct(mm, area); spin_unlock(&mm->page_table_lock); + unlock_vma_mappings(area); return extra; } @@ -811,10 +855,12 @@ unsigned long do_brk(unsigned long addr, unsigned long len) flags = vma->vm_flags; addr = vma->vm_start; + lock_vma_mappings(vma); spin_lock(&mm->page_table_lock); - insert_vm_struct(mm, vma); + __insert_vm_struct(mm, vma); merge_segments(mm, vma->vm_start, vma->vm_end); spin_unlock(&mm->page_table_lock); + unlock_vma_mappings(vma); mm->total_vm += len >> PAGE_SHIFT; if (flags & VM_LOCKED) { @@ -877,9 +923,10 @@ void exit_mmap(struct mm_struct * mm) } /* Insert vm structure into process list sorted by address - * and into the inode's i_mmap ring. + * and into the inode's i_mmap ring. If vm_file is non-NULL + * then the i_shared_lock must be held here. */ -void insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vmp) +void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vmp) { struct vm_area_struct **pprev; struct file * file; @@ -916,15 +963,20 @@ void insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vmp) head = &mapping->i_mmap_shared; /* insert vmp into inode's share list */ - spin_lock(&mapping->i_shared_lock); if((vmp->vm_next_share = *head) != NULL) (*head)->vm_pprev_share = &vmp->vm_next_share; *head = vmp; vmp->vm_pprev_share = head; - spin_unlock(&mapping->i_shared_lock); } } +void insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vmp) +{ + lock_vma_mappings(vmp); + __insert_vm_struct(mm, vmp); + unlock_vma_mappings(vmp); +} + /* Merge the list of memory segments if possible. * Redundant vm_area_structs are freed. * This assumes that the list is ordered by address. @@ -986,11 +1038,13 @@ void merge_segments (struct mm_struct * mm, unsigned long start_addr, unsigned l mpnt->vm_pgoff += (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT; mpnt->vm_start = mpnt->vm_end; spin_unlock(&mm->page_table_lock); + unlock_vma_mappings(mpnt); mpnt->vm_ops->close(mpnt); + lock_vma_mappings(mpnt); spin_lock(&mm->page_table_lock); } mm->map_count--; - remove_shared_vm_struct(mpnt); + __remove_shared_vm_struct(mpnt); if (mpnt->vm_file) fput(mpnt->vm_file); kmem_cache_free(vm_area_cachep, mpnt); |