diff options
| -rw-r--r-- | include/linux/mm_types.h | 9 | ||||
| -rw-r--r-- | mm/mmap.c | 143 |
2 files changed, 141 insertions, 11 deletions
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 31f8a3a..94fa52b 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -238,6 +238,14 @@ struct vm_area_struct { struct rb_node vm_rb; /* + * Largest free memory gap in bytes to the left of this VMA. + * Either between this VMA and vma->vm_prev, or between one of the + * VMAs below us in the VMA rbtree and its ->vm_prev. This helps + * get_unmapped_area find a free area of the right size. + */ + unsigned long rb_subtree_gap; + + /* * For areas with an address space and backing store, * linkage into the address_space->i_mmap interval tree, or * linkage of vma in the address_space->i_mmap_nonlinear list. @@ -322,6 +330,7 @@ struct mm_struct { unsigned long task_size; /* size of task vm space */ unsigned long cached_hole_size; /* if non-zero, the largest hole below free_area_cache */ unsigned long free_area_cache; /* first hole of size cached_hole_size or larger */ + unsigned long highest_vm_end; /* highest vma end address */ pgd_t * pgd; atomic_t mm_users; /* How many users with user space? */ atomic_t mm_count; /* How many references to "struct mm_struct" (users count as 1) */ @@ -31,6 +31,7 @@ #include <linux/audit.h> #include <linux/khugepaged.h> #include <linux/uprobes.h> +#include <linux/rbtree_augmented.h> #include <asm/uaccess.h> #include <asm/cacheflush.h> @@ -297,6 +298,27 @@ out: return retval; } +static long vma_compute_subtree_gap(struct vm_area_struct *vma) +{ + unsigned long max, subtree_gap; + max = vma->vm_start; + if (vma->vm_prev) + max -= vma->vm_prev->vm_end; + if (vma->vm_rb.rb_left) { + subtree_gap = rb_entry(vma->vm_rb.rb_left, + struct vm_area_struct, vm_rb)->rb_subtree_gap; + if (subtree_gap > max) + max = subtree_gap; + } + if (vma->vm_rb.rb_right) { + subtree_gap = rb_entry(vma->vm_rb.rb_right, + struct vm_area_struct, vm_rb)->rb_subtree_gap; + if (subtree_gap > max) + max = subtree_gap; + } + return max; +} + #ifdef CONFIG_DEBUG_VM_RB static int browse_rb(struct rb_root *root) { @@ -327,6 +349,18 @@ static int browse_rb(struct rb_root *root) return i; } +static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore) +{ + struct rb_node *nd; + + for (nd = rb_first(root); nd; nd = rb_next(nd)) { + struct vm_area_struct *vma; + vma = rb_entry(nd, struct vm_area_struct, vm_rb); + BUG_ON(vma != ignore && + vma->rb_subtree_gap != vma_compute_subtree_gap(vma)); + } +} + void validate_mm(struct mm_struct *mm) { int bug = 0; @@ -349,9 +383,52 @@ void validate_mm(struct mm_struct *mm) BUG_ON(bug); } #else +#define validate_mm_rb(root, ignore) do { } while (0) #define validate_mm(mm) do { } while (0) #endif +RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb, + unsigned long, rb_subtree_gap, vma_compute_subtree_gap) + +/* + * Update augmented rbtree rb_subtree_gap values after vma->vm_start or + * vma->vm_prev->vm_end values changed, without modifying the vma's position + * in the rbtree. + */ +static void vma_gap_update(struct vm_area_struct *vma) +{ + /* + * As it turns out, RB_DECLARE_CALLBACKS() already created a callback + * function that does exacltly what we want. + */ + vma_gap_callbacks_propagate(&vma->vm_rb, NULL); +} + +static inline void vma_rb_insert(struct vm_area_struct *vma, + struct rb_root *root) +{ + /* All rb_subtree_gap values must be consistent prior to insertion */ + validate_mm_rb(root, NULL); + + rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks); +} + +static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root) +{ + /* + * All rb_subtree_gap values must be consistent prior to erase, + * with the possible exception of the vma being erased. + */ + validate_mm_rb(root, vma); + + /* + * Note rb_erase_augmented is a fairly large inline function, + * so make sure we instantiate it only once with our desired + * augmented rbtree callbacks. + */ + rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks); +} + /* * vma has some anon_vma assigned, and is already inserted on that * anon_vma's interval trees. @@ -421,8 +498,25 @@ static int find_vma_links(struct mm_struct *mm, unsigned long addr, void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, struct rb_node **rb_link, struct rb_node *rb_parent) { + /* Update tracking information for the gap following the new vma. */ + if (vma->vm_next) + vma_gap_update(vma->vm_next); + else + mm->highest_vm_end = vma->vm_end; + + /* + * vma->vm_prev wasn't known when we followed the rbtree to find the + * correct insertion point for that vma. As a result, we could not + * update the vma vm_rb parents rb_subtree_gap values on the way down. + * So, we first insert the vma with a zero rb_subtree_gap value + * (to be consistent with what we did on the way down), and then + * immediately update the gap to the correct value. Finally we + * rebalance the rbtree after all augmented values have been set. + */ rb_link_node(&vma->vm_rb, rb_parent, rb_link); - rb_insert_color(&vma->vm_rb, &mm->mm_rb); + vma->rb_subtree_gap = 0; + vma_gap_update(vma); + vma_rb_insert(vma, &mm->mm_rb); } static void __vma_link_file(struct vm_area_struct *vma) @@ -498,12 +592,12 @@ static inline void __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma, struct vm_area_struct *prev) { - struct vm_area_struct *next = vma->vm_next; + struct vm_area_struct *next; - prev->vm_next = next; + vma_rb_erase(vma, &mm->mm_rb); + prev->vm_next = next = vma->vm_next; if (next) next->vm_prev = prev; - rb_erase(&vma->vm_rb, &mm->mm_rb); if (mm->mmap_cache == vma) mm->mmap_cache = prev; } @@ -525,6 +619,7 @@ int vma_adjust(struct vm_area_struct *vma, unsigned long start, struct rb_root *root = NULL; struct anon_vma *anon_vma = NULL; struct file *file = vma->vm_file; + bool start_changed = false, end_changed = false; long adjust_next = 0; int remove_next = 0; @@ -615,8 +710,14 @@ again: remove_next = 1 + (end > next->vm_end); vma_interval_tree_remove(next, root); } - vma->vm_start = start; - vma->vm_end = end; + if (start != vma->vm_start) { + vma->vm_start = start; + start_changed = true; + } + if (end != vma->vm_end) { + vma->vm_end = end; + end_changed = true; + } vma->vm_pgoff = pgoff; if (adjust_next) { next->vm_start += adjust_next << PAGE_SHIFT; @@ -645,6 +746,15 @@ again: remove_next = 1 + (end > next->vm_end); * (it may either follow vma or precede it). */ __insert_vm_struct(mm, insert); + } else { + if (start_changed) + vma_gap_update(vma); + if (end_changed) { + if (!next) + mm->highest_vm_end = end; + else if (!adjust_next) + vma_gap_update(next); + } } if (anon_vma) { @@ -678,10 +788,13 @@ again: remove_next = 1 + (end > next->vm_end); * we must remove another next too. It would clutter * up the code too much to do both in one go. */ - if (remove_next == 2) { - next = vma->vm_next; + next = vma->vm_next; + if (remove_next == 2) goto again; - } + else if (next) + vma_gap_update(next); + else + mm->highest_vm_end = end; } if (insert && file) uprobe_mmap(insert); @@ -1784,6 +1897,10 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address) anon_vma_interval_tree_pre_update_vma(vma); vma->vm_end = address; anon_vma_interval_tree_post_update_vma(vma); + if (vma->vm_next) + vma_gap_update(vma->vm_next); + else + vma->vm_mm->highest_vm_end = address; perf_event_mmap(vma); } } @@ -1838,6 +1955,7 @@ int expand_downwards(struct vm_area_struct *vma, vma->vm_start = address; vma->vm_pgoff -= grow; anon_vma_interval_tree_post_update_vma(vma); + vma_gap_update(vma); perf_event_mmap(vma); } } @@ -1960,14 +2078,17 @@ detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, insertion_point = (prev ? &prev->vm_next : &mm->mmap); vma->vm_prev = NULL; do { - rb_erase(&vma->vm_rb, &mm->mm_rb); + vma_rb_erase(vma, &mm->mm_rb); mm->map_count--; tail_vma = vma; vma = vma->vm_next; } while (vma && vma->vm_start < end); *insertion_point = vma; - if (vma) + if (vma) { vma->vm_prev = prev; + vma_gap_update(vma); + } else + mm->highest_vm_end = prev ? prev->vm_end : 0; tail_vma->vm_next = NULL; if (mm->unmap_area == arch_unmap_area) addr = prev ? prev->vm_end : mm->mmap_base; |
