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

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>

1 files changed, 8 insertions, 21 deletions

diff --git a/arch/x86_64/mm/ioremap.c b/arch/x86_64/mm/ioremap.c
index c6fb0cb69992..58aac23760ef 100644
--- a/arch/x86_64/mm/ioremap.c
+++ b/arch/x86_64/mm/ioremap.c
@@ -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); 
 }