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nommu: fix a number of issues with the per-MM VMA patch

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Fix a number of issues with the per-MM VMA patch:

 (1) Make mmap_pages_allocated an atomic_long_t, just in case this is used on
     a NOMMU system with more than 2G pages.  Makes no difference on a 32-bit
     system.

 (2) Report vma->vm_pgoff * PAGE_SIZE as a 64-bit value, not a 32-bit value,
     lest it overflow.

 (3) Move the allocation of the vm_area_struct slab back for fork.c.

 (4) Use KMEM_CACHE() for both vm_area_struct and vm_region slabs.

 (5) Use BUG_ON() rather than if () BUG().

 (6) Make the default validate_nommu_regions() a static inline rather than a
     #define.

 (7) Make free_page_series()'s objection to pages with a refcount != 1 more
     informative.

 (8) Adjust the __put_nommu_region() banner comment to indicate that the
     semaphore must be held for writing.

 (9) Limit the number of warnings about munmaps of non-mmapped regions.

Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Greg Ungerer <gerg@snapgear.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Howells 2009-04-02 16:56:32 -07:00 committed by Linus Torvalds
parent 5482415a5e
commit 33e5d76979
6 changed files with 30 additions and 34 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
fs/proc/meminfo.c
View file

@ -120,7 +120,7 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
K(i.freeram-i.freehigh),
#endif
#ifndef CONFIG_MMU
K((unsigned long) atomic_read(&mmap_pages_allocated)),
K((unsigned long) atomic_long_read(&mmap_pages_allocated)),
#endif
K(i.totalswap),
K(i.freeswap),

4
fs/proc/task_nommu.c
View file

@ -136,14 +136,14 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma)
}
seq_printf(m,
"%08lx-%08lx %c%c%c%c %08lx %02x:%02x %lu %n",
"%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
vma->vm_start,
vma->vm_end,
flags & VM_READ ? 'r' : '-',
flags & VM_WRITE ? 'w' : '-',
flags & VM_EXEC ? 'x' : '-',
flags & VM_MAYSHARE ? flags & VM_SHARED ? 'S' : 's' : 'p',
vma->vm_pgoff << PAGE_SHIFT,
(unsigned long long) vma->vm_pgoff << PAGE_SHIFT,
MAJOR(dev), MINOR(dev), ino, &len);
if (file) {

2
include/linux/mm.h
View file

@ -1079,7 +1079,7 @@ static inline void setup_per_cpu_pageset(void) {}
#endif
/* nommu.c */
extern atomic_t mmap_pages_allocated;
extern atomic_long_t mmap_pages_allocated;
/* prio_tree.c */
void vma_prio_tree_add(struct vm_area_struct *, struct vm_area_struct *old);

1
kernel/fork.c
View file

@ -1488,6 +1488,7 @@ void __init proc_caches_init(void)
mm_cachep = kmem_cache_create("mm_struct",
sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC);
mmap_init();
}

3
mm/mmap.c
View file

@ -2481,7 +2481,4 @@ void mm_drop_all_locks(struct mm_struct *mm)
*/
void __init mmap_init(void)
{
vm_area_cachep = kmem_cache_create("vm_area_struct",
sizeof(struct vm_area_struct), 0,
SLAB_PANIC, NULL);
}

50
mm/nommu.c
View file

@ -69,7 +69,7 @@ int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
int sysctl_nr_trim_pages = 1; /* page trimming behaviour */
int heap_stack_gap = 0;
atomic_t mmap_pages_allocated;
atomic_long_t mmap_pages_allocated;
EXPORT_SYMBOL(mem_map);
EXPORT_SYMBOL(num_physpages);
@ -463,12 +463,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
*/
void __init mmap_init(void)
{
vm_region_jar = kmem_cache_create("vm_region_jar",
sizeof(struct vm_region), 0,
SLAB_PANIC, NULL);
vm_area_cachep = kmem_cache_create("vm_area_struct",
sizeof(struct vm_area_struct), 0,
SLAB_PANIC, NULL);
vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC);
}
/*
@ -486,27 +481,24 @@ static noinline void validate_nommu_regions(void)
return;
last = rb_entry(lastp, struct vm_region, vm_rb);
if (unlikely(last->vm_end <= last->vm_start))
BUG();
if (unlikely(last->vm_top < last->vm_end))
BUG();
BUG_ON(unlikely(last->vm_end <= last->vm_start));
BUG_ON(unlikely(last->vm_top < last->vm_end));
while ((p = rb_next(lastp))) {
region = rb_entry(p, struct vm_region, vm_rb);
last = rb_entry(lastp, struct vm_region, vm_rb);
if (unlikely(region->vm_end <= region->vm_start))
BUG();
if (unlikely(region->vm_top < region->vm_end))
BUG();
if (unlikely(region->vm_start < last->vm_top))
BUG();
BUG_ON(unlikely(region->vm_end <= region->vm_start));
BUG_ON(unlikely(region->vm_top < region->vm_end));
BUG_ON(unlikely(region->vm_start < last->vm_top));
lastp = p;
}
}
#else
#define validate_nommu_regions() do {} while(0)
static void validate_nommu_regions(void)
{
}
#endif
/*
@ -563,16 +555,17 @@ static void free_page_series(unsigned long from, unsigned long to)
struct page *page = virt_to_page(from);
kdebug("- free %lx", from);
atomic_dec(&mmap_pages_allocated);
atomic_long_dec(&mmap_pages_allocated);
if (page_count(page) != 1)
kdebug("free page %p [%d]", page, page_count(page));
kdebug("free page %p: refcount not one: %d",
page, page_count(page));
put_page(page);
}
}
/*
* release a reference to a region
* - the caller must hold the region semaphore, which this releases
* - the caller must hold the region semaphore for writing, which this releases
* - the region may not have been added to the tree yet, in which case vm_top
* will equal vm_start
*/
@ -1096,7 +1089,7 @@ static int do_mmap_private(struct vm_area_struct *vma,
goto enomem;
total = 1 << order;
atomic_add(total, &mmap_pages_allocated);
atomic_long_add(total, &mmap_pages_allocated);
point = rlen >> PAGE_SHIFT;
@ -1107,7 +1100,7 @@ static int do_mmap_private(struct vm_area_struct *vma,
order = ilog2(total - point);
n = 1 << order;
kdebug("shave %lu/%lu @%lu", n, total - point, total);
atomic_sub(n, &mmap_pages_allocated);
atomic_long_sub(n, &mmap_pages_allocated);
total -= n;
set_page_refcounted(pages + total);
__free_pages(pages + total, order);
@ -1536,10 +1529,15 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
/* find the first potentially overlapping VMA */
vma = find_vma(mm, start);
if (!vma) {
static int limit = 0;
if (limit < 5) {
printk(KERN_WARNING
"munmap of memory not mmapped by process %d (%s):"
" 0x%lx-0x%lx\n",
current->pid, current->comm, start, start + len - 1);
"munmap of memory not mmapped by process %d"
" (%s): 0x%lx-0x%lx\n",
current->pid, current->comm,
start, start + len - 1);
limit++;
}
return -EINVAL;
}