[PATCH 03/16] mm: check rb_subtree_gap correctness
From: akpm@linux-foundation.org (Andrew Morton)
Date: 2012-11-06 22:38:19
Also in:
linux-mips, linux-mm, linux-sh, lkml, sparclinux
On Mon, 5 Nov 2012 14:47:00 -0800 Michel Lespinasse [off-list ref] wrote:
quoted hunk ↗ jump to hunk
When CONFIG_DEBUG_VM_RB is enabled, check that rb_subtree_gap is correctly set for every vma and that mm->highest_vm_end is also correct. Also add an explicit 'bug' variable to track if browse_rb() detected any invalid condition. ...@@ -365,7 +365,7 @@ static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root) #ifdef CONFIG_DEBUG_VM_RB static int browse_rb(struct rb_root *root) { - int i = 0, j; + int i = 0, j, bug = 0; struct rb_node *nd, *pn = NULL; unsigned long prev = 0, pend = 0;@@ -373,29 +373,33 @@ static int browse_rb(struct rb_root *root) struct vm_area_struct *vma; vma = rb_entry(nd, struct vm_area_struct, vm_rb); if (vma->vm_start < prev) - printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1; + printk("vm_start %lx prev %lx\n", vma->vm_start, prev), bug = 1; if (vma->vm_start < pend) - printk("vm_start %lx pend %lx\n", vma->vm_start, pend); + printk("vm_start %lx pend %lx\n", vma->vm_start, pend), bug = 1; if (vma->vm_start > vma->vm_end) - printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start); + printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start), bug = 1; + if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) + printk("free gap %lx, correct %lx\n", + vma->rb_subtree_gap, + vma_compute_subtree_gap(vma)), bug = 1;
OK, now who did that. Whoever it was: stop it or you'll have your kernel license revoked!
--- a/mm/mmap.c~mm-check-rb_subtree_gap-correctness-fix
+++ a/mm/mmap.c@@ -372,16 +372,25 @@ static int browse_rb(struct rb_root *roo 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); - if (vma->vm_start < prev) - printk("vm_start %lx prev %lx\n", vma->vm_start, prev), bug = 1; - if (vma->vm_start < pend) - printk("vm_start %lx pend %lx\n", vma->vm_start, pend), bug = 1; - if (vma->vm_start > vma->vm_end) - printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start), bug = 1; - if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) + if (vma->vm_start < prev) { + printk("vm_start %lx prev %lx\n", vma->vm_start, prev); + bug = 1; + } + if (vma->vm_start < pend) { + printk("vm_start %lx pend %lx\n", vma->vm_start, pend); + bug = 1; + } + if (vma->vm_start > vma->vm_end) { + printk("vm_end %lx < vm_start %lx\n", + vma->vm_end, vma->vm_start); + bug = 1; + } + if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) { printk("free gap %lx, correct %lx\n", vma->rb_subtree_gap, - vma_compute_subtree_gap(vma)), bug = 1; + vma_compute_subtree_gap(vma)); + bug = 1; + } i++; pn = nd; prev = vma->vm_start;
@@ -390,8 +399,10 @@ static int browse_rb(struct rb_root *roo j = 0; for (nd = pn; nd; nd = rb_prev(nd)) j++; - if (i != j) - printk("backwards %d, forwards %d\n", j, i), bug = 1; + if (i != j) { + printk("backwards %d, forwards %d\n", j, i); + bug = 1; + } return bug ? -1 : i; }
@@ -411,14 +422,20 @@ void validate_mm(struct mm_struct *mm) vma = vma->vm_next; i++; } - if (i != mm->map_count) - printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1; - if (highest_address != mm->highest_vm_end) + if (i != mm->map_count) { + printk("map_count %d vm_next %d\n", mm->map_count, i); + bug = 1; + } + if (highest_address != mm->highest_vm_end) { printk("mm->highest_vm_end %lx, found %lx\n", - mm->highest_vm_end, highest_address), bug = 1; + mm->highest_vm_end, highest_address); + bug = 1; + } i = browse_rb(&mm->mm_rb); - if (i != mm->map_count) - printk("map_count %d rb %d\n", mm->map_count, i), bug = 1; + if (i != mm->map_count) { + printk("map_count %d rb %d\n", mm->map_count, i); + bug = 1; + } BUG_ON(bug); } #else