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[PATCH] x86_64: Fixed guard page handling again in iounmap

Browse source 
Caused oopses again.  Also fix potential mismatch in checking if
change_page_attr was needed.

To do it without races I needed to change mm/vmalloc.c to export a
__remove_vm_area that does not take vmlist lock.

Noticed by Terence Ripperda and based on a patch of his.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Andi Kleen 2005-05-20 14:27:57 -07:00 committed by Linus Torvalds
parent c4d1fcf3a2
commit 7856dfeb23
3 changed files with 35 additions and 40 deletions
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29
arch/x86_64/mm/ioremap.c
View file

@ -133,7 +133,7 @@ ioremap_change_attr(unsigned long phys_addr, unsigned long size,
unsigned long flags)
{
int err = 0;
if (flags && phys_addr + size - 1 < (end_pfn_map << PAGE_SHIFT)) {
if (phys_addr + size - 1 < (end_pfn_map << PAGE_SHIFT)) {
unsigned long npages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
unsigned long vaddr = (unsigned long) __va(phys_addr);
@ -214,7 +214,7 @@ void __iomem * __ioremap(unsigned long phys_addr, unsigned long size, unsigned l
remove_vm_area((void *)(PAGE_MASK & (unsigned long) addr));
return NULL;
}
if (ioremap_change_attr(phys_addr, size, flags) < 0) {
if (flags && ioremap_change_attr(phys_addr, size, flags) < 0) {
area->flags &= 0xffffff;
vunmap(addr);
return NULL;
@ -251,7 +251,7 @@ void __iomem *ioremap_nocache (unsigned long phys_addr, unsigned long size)
void iounmap(volatile void __iomem *addr)
{
struct vm_struct *p, **pprev;
struct vm_struct *p;
if (addr <= high_memory)
return;
@ -260,24 +260,11 @@ void iounmap(volatile void __iomem *addr)
return;
write_lock(&vmlist_lock);
for (p = vmlist, pprev = &vmlist; p != NULL; pprev = &p->next, p = *pprev)
if (p->addr == (void *)(PAGE_MASK & (unsigned long)addr))
break;
if (!p) {
printk("__iounmap: bad address %p\n", addr);
goto out_unlock;
}
*pprev = p->next;
unmap_vm_area(p);
if ((p->flags >> 20) &&
p->phys_addr + p->size - 1 < virt_to_phys(high_memory)) {
/* p->size includes the guard page, but cpa doesn't like that */
change_page_attr_addr((unsigned long)__va(p->phys_addr),
p->size >> PAGE_SHIFT,
PAGE_KERNEL);
global_flush_tlb();
}
out_unlock:
p = __remove_vm_area((void *)((unsigned long)addr & PAGE_MASK));
if (!p)
printk("iounmap: bad address %p\n", addr);
else if (p->flags >> 20)
ioremap_change_attr(p->phys_addr, p->size, 0);
write_unlock(&vmlist_lock);
kfree(p);
}

1
include/linux/vmalloc.h
View file

@ -41,6 +41,7 @@ extern struct vm_struct *get_vm_area(unsigned long size, unsigned long flags);
extern struct vm_struct *__get_vm_area(unsigned long size, unsigned long flags,
unsigned long start, unsigned long end);
extern struct vm_struct *remove_vm_area(void *addr);
extern struct vm_struct *__remove_vm_area(void *addr);
extern int map_vm_area(struct vm_struct *area, pgprot_t prot,
struct page ***pages);
extern void unmap_vm_area(struct vm_struct *area);

45
mm/vmalloc.c
View file

@ -248,6 +248,28 @@ struct vm_struct *get_vm_area(unsigned long size, unsigned long flags)
return __get_vm_area(size, flags, VMALLOC_START, VMALLOC_END);
}
/* Caller must hold vmlist_lock */
struct vm_struct *__remove_vm_area(void *addr)
{
struct vm_struct **p, *tmp;
for (p = &vmlist ; (tmp = *p) != NULL ;p = &tmp->next) {
if (tmp->addr == addr)
goto found;
}
return NULL;
found:
unmap_vm_area(tmp);
*p = tmp->next;
/*
* Remove the guard page.
*/
tmp->size -= PAGE_SIZE;
return tmp;
}
/**
* remove_vm_area - find and remove a contingous kernel virtual area
*
@ -255,30 +277,15 @@ struct vm_struct *get_vm_area(unsigned long size, unsigned long flags)
*
* Search for the kernel VM area starting at @addr, and remove it.
* This function returns the found VM area, but using it is NOT safe
* on SMP machines.
* on SMP machines, except for its size or flags.
*/
struct vm_struct *remove_vm_area(void *addr)
{
struct vm_struct **p, *tmp;
struct vm_struct *v;
write_lock(&vmlist_lock);
for (p = &vmlist ; (tmp = *p) != NULL ;p = &tmp->next) {
if (tmp->addr == addr)
goto found;
}
v = __remove_vm_area(addr);
write_unlock(&vmlist_lock);
return NULL;
found:
unmap_vm_area(tmp);
*p = tmp->next;
write_unlock(&vmlist_lock);
/*
* Remove the guard page.
*/
tmp->size -= PAGE_SIZE;
return tmp;
return v;
}
void __vunmap(void *addr, int deallocate_pages)