[PATCH 3/3] mm/vmalloc: correct a few logic error in __insert_vmap_area()

From: zijun_hu
Date: Tue Sep 20 2016 - 02:03:31 EST

From: zijun_hu <zijun_hu@xxxxxxx>

correct a few logic error in __insert_vmap_area() since the else if
condition is always true and meaningless

avoid endless loop under [un]mapping improper ranges whose boundary
are not aligned to page

correct lazy_max_pages() return value if the number of online cpus
is power of 2

improve performance for pcpu_get_vm_areas() via optimizing vmap_areas
overlay checking algorithm and finding near vmap_areas by list_head
other than rbtree

simplify /proc/vmallocinfo implementation via seq_file helpers
for list_head

Signed-off-by: zijun_hu <zijun_hu@xxxxxxx>
Signed-off-by: zijun_hu <zijun_hu@xxxxxxxx>
---
include/linux/list.h | 11 ++++++
mm/internal.h | 6 +++
mm/memblock.c | 10 +----
mm/vmalloc.c | 104 +++++++++++++++++++++++++++------------------------
4 files changed, 74 insertions(+), 57 deletions(-)

diff --git a/include/linux/list.h b/include/linux/list.h
index 5183138..23c3081 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -181,6 +181,17 @@ static inline int list_is_last(const struct list_head *list,
}

/**
+ * list_is_first - tests whether @list is the first entry in list @head
+ * @list: the entry to test
+ * @head: the head of the list
+ */
+static inline int list_is_first(const struct list_head *list,
+ const struct list_head *head)
+{
+ return list->prev == head;
+}
+
+/**
* list_empty - tests whether a list is empty
* @head: the list to test.
*/
diff --git a/mm/internal.h b/mm/internal.h
index 1501304..abbff7c 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -71,6 +71,12 @@ static inline void set_page_refcounted(struct page *page)
set_page_count(page, 1);
}

+/**
+ * check whether range [@s0, @e0) has intersection with [@s1, @e1)
+ */
+#define is_range_overlay(s0, e0, s1, e1) \
+ (((s1) >= (e0) || (s0) >= (e1)) ? false : true)
+
extern unsigned long highest_memmap_pfn;

/*
diff --git a/mm/memblock.c b/mm/memblock.c
index 483197e..b4c7d7c 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -85,20 +85,14 @@ static inline phys_addr_t memblock_cap_size(phys_addr_t base, phys_addr_t *size)
/*
* Address comparison utilities
*/
-static unsigned long __init_memblock memblock_addrs_overlap(phys_addr_t base1, phys_addr_t size1,
- phys_addr_t base2, phys_addr_t size2)
-{
- return ((base1 < (base2 + size2)) && (base2 < (base1 + size1)));
-}
-
bool __init_memblock memblock_overlaps_region(struct memblock_type *type,
phys_addr_t base, phys_addr_t size)
{
unsigned long i;

for (i = 0; i < type->cnt; i++)
- if (memblock_addrs_overlap(base, size, type->regions[i].base,
- type->regions[i].size))
+ if (is_range_overlay(base, base + size, type->regions[i].base,
+ type->regions[i].base + type->regions[i].size))
break;
return i < type->cnt;
}
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 91f44e7..dc938f6 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -67,7 +67,7 @@ static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end)
do {
pte_t ptent = ptep_get_and_clear(&init_mm, addr, pte);
WARN_ON(!pte_none(ptent) && !pte_present(ptent));
- } while (pte++, addr += PAGE_SIZE, addr != end);
+ } while (pte++, addr += PAGE_SIZE, addr < end && addr >= PAGE_SIZE);
}

static void vunmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end)
@@ -108,6 +108,9 @@ static void vunmap_page_range(unsigned long addr, unsigned long end)
unsigned long next;

BUG_ON(addr >= end);
+ WARN_ON(!PAGE_ALIGNED(addr | end));
+
+ addr = round_down(addr, PAGE_SIZE);
pgd = pgd_offset_k(addr);
do {
next = pgd_addr_end(addr, end);
@@ -139,7 +142,7 @@ static int vmap_pte_range(pmd_t *pmd, unsigned long addr,
return -ENOMEM;
set_pte_at(&init_mm, addr, pte, mk_pte(page, prot));
(*nr)++;
- } while (pte++, addr += PAGE_SIZE, addr != end);
+ } while (pte++, addr += PAGE_SIZE, addr < end && addr >= PAGE_SIZE);
return 0;
}

@@ -193,6 +196,9 @@ static int vmap_page_range_noflush(unsigned long start, unsigned long end,
int nr = 0;

BUG_ON(addr >= end);
+ WARN_ON(!PAGE_ALIGNED(addr | end));
+
+ addr = round_down(addr, PAGE_SIZE);
pgd = pgd_offset_k(addr);
do {
next = pgd_addr_end(addr, end);
@@ -291,6 +297,22 @@ static unsigned long cached_align;

static unsigned long vmap_area_pcpu_hole;

+static inline struct vmap_area *next_vmap_area(struct vmap_area *va)
+{
+ if (list_is_last(&va->list, &vmap_area_list))
+ return NULL;
+ else
+ return list_next_entry(va, list);
+}
+
+static inline struct vmap_area *prev_vmap_area(struct vmap_area *va)
+{
+ if (list_is_first(&va->list, &vmap_area_list))
+ return NULL;
+ else
+ return list_prev_entry(va, list);
+}
+
static struct vmap_area *__find_vmap_area(unsigned long addr)
{
struct rb_node *n = vmap_area_root.rb_node;
@@ -321,10 +343,10 @@ static void __insert_vmap_area(struct vmap_area *va)

parent = *p;
tmp_va = rb_entry(parent, struct vmap_area, rb_node);
- if (va->va_start < tmp_va->va_end)
- p = &(*p)->rb_left;
- else if (va->va_end > tmp_va->va_start)
- p = &(*p)->rb_right;
+ if (va->va_end <= tmp_va->va_start)
+ p = &parent->rb_left;
+ else if (va->va_start >= tmp_va->va_end)
+ p = &parent->rb_right;
else
BUG();
}
@@ -594,7 +616,9 @@ static unsigned long lazy_max_pages(void)
{
unsigned int log;

- log = fls(num_online_cpus());
+ log = num_online_cpus();
+ if (log > 1)
+ log = (unsigned int)get_count_order(log);

return log * (32UL * 1024 * 1024 / PAGE_SIZE);
}
@@ -1110,7 +1134,7 @@ void vm_unmap_ram(const void *mem, unsigned int count)

BUG_ON(!addr);
BUG_ON(addr < VMALLOC_START);
- BUG_ON(addr > VMALLOC_END);
+ BUG_ON(addr >= VMALLOC_END);
BUG_ON(!PAGE_ALIGNED(addr));

debug_check_no_locks_freed(mem, size);
@@ -2294,10 +2318,6 @@ void free_vm_area(struct vm_struct *area)
EXPORT_SYMBOL_GPL(free_vm_area);

#ifdef CONFIG_SMP
-static struct vmap_area *node_to_va(struct rb_node *n)
-{
- return n ? rb_entry(n, struct vmap_area, rb_node) : NULL;
-}

/**
* pvm_find_next_prev - find the next and prev vmap_area surrounding @end
@@ -2333,10 +2353,10 @@ static bool pvm_find_next_prev(unsigned long end,

if (va->va_end > end) {
*pnext = va;
- *pprev = node_to_va(rb_prev(&(*pnext)->rb_node));
+ *pprev = prev_vmap_area(va);
} else {
*pprev = va;
- *pnext = node_to_va(rb_next(&(*pprev)->rb_node));
+ *pnext = next_vmap_area(va);
}
return true;
}
@@ -2371,7 +2391,7 @@ static unsigned long pvm_determine_end(struct vmap_area **pnext,

while (*pprev && (*pprev)->va_end > addr) {
*pnext = *pprev;
- *pprev = node_to_va(rb_prev(&(*pnext)->rb_node));
+ *pprev = prev_vmap_area(*pnext);
}

return addr;
@@ -2411,31 +2431,34 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
struct vm_struct **vms;
int area, area2, last_area, term_area;
unsigned long base, start, end, last_end;
+ unsigned long start2, end2;
bool purged = false;

/* verify parameters and allocate data structures */
+ if (nr_vms < 1)
+ return NULL;
BUG_ON(offset_in_page(align) || !is_power_of_2(align));
- for (last_area = 0, area = 0; area < nr_vms; area++) {
+
+ last_area = nr_vms - 1;
+ BUG_ON(!IS_ALIGNED(offsets[last_area], align));
+ BUG_ON(!IS_ALIGNED(sizes[last_area], align));
+ for (area = 0; area < nr_vms - 1; area++) {
start = offsets[area];
end = start + sizes[area];

/* is everything aligned properly? */
- BUG_ON(!IS_ALIGNED(offsets[area], align));
- BUG_ON(!IS_ALIGNED(sizes[area], align));
+ BUG_ON(!IS_ALIGNED(start, align));
+ BUG_ON(!IS_ALIGNED(end, align));

/* detect the area with the highest address */
if (start > offsets[last_area])
last_area = area;

- for (area2 = 0; area2 < nr_vms; area2++) {
- unsigned long start2 = offsets[area2];
- unsigned long end2 = start2 + sizes[area2];
-
- if (area2 == area)
- continue;
+ for (area2 = area + 1; area2 < nr_vms; area2++) {
+ start2 = offsets[area2];
+ end2 = start2 + sizes[area2];

- BUG_ON(start2 >= start && start2 < end);
- BUG_ON(end2 <= end && end2 > start);
+ BUG_ON(is_range_overlay(start, end, start2, end2));
}
}
last_end = offsets[last_area] + sizes[last_area];
@@ -2505,7 +2528,7 @@ retry:
*/
if (prev && prev->va_end > base + start) {
next = prev;
- prev = node_to_va(rb_prev(&next->rb_node));
+ prev = prev_vmap_area(next);
base = pvm_determine_end(&next, &prev, align) - end;
term_area = area;
continue;
@@ -2576,32 +2599,13 @@ void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
static void *s_start(struct seq_file *m, loff_t *pos)
__acquires(&vmap_area_lock)
{
- loff_t n = *pos;
- struct vmap_area *va;
-
spin_lock(&vmap_area_lock);
- va = list_first_entry(&vmap_area_list, typeof(*va), list);
- while (n > 0 && &va->list != &vmap_area_list) {
- n--;
- va = list_next_entry(va, list);
- }
- if (!n && &va->list != &vmap_area_list)
- return va;
-
- return NULL;
-
+ return seq_list_start(&vmap_area_list, *pos);
}

static void *s_next(struct seq_file *m, void *p, loff_t *pos)
{
- struct vmap_area *va = p, *next;
-
- ++*pos;
- next = list_next_entry(va, list);
- if (&next->list != &vmap_area_list)
- return next;
-
- return NULL;
+ return seq_list_next(p, &vmap_area_list, pos);
}

static void s_stop(struct seq_file *m, void *p)
@@ -2636,9 +2640,11 @@ static void show_numa_info(struct seq_file *m, struct vm_struct *v)

static int s_show(struct seq_file *m, void *p)
{
- struct vmap_area *va = p;
+ struct vmap_area *va;
struct vm_struct *v;

+ va = list_entry((struct list_head *)p, struct vmap_area, list);
+
/*
* s_show can encounter race with remove_vm_area, !VM_VM_AREA on
* behalf of vmap area is being tear down or vm_map_ram allocation.
--
1.9.1