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Subject[patch 2/6] mmu_notifier: Callbacks to invalidate address ranges
The invalidation of address ranges in a mm_struct needs to be
performed when pages are removed or permissions etc change.
Most of the VM address space changes can use the range invalidate
callback.

invalidate_range() is generally called with mmap_sem held but
no spinlocks are active. If invalidate_range() is called with
locks held then we pass a flag into invalidate_range()

Comments state that mmap_sem must be held for
remap_pfn_range() but various drivers do not seem to do this.

Signed-off-by: Andrea Arcangeli <andrea@qumranet.com>
Signed-off-by: Robin Holt <holt@sgi.com>
Signed-off-by: Christoph Lameter <clameter@sgi.com>

---
mm/fremap.c | 2 ++
mm/hugetlb.c | 2 ++
mm/memory.c | 11 +++++++++--
mm/mmap.c | 1 +
4 files changed, 14 insertions(+), 2 deletions(-)
Index: linux-2.6/mm/fremap.c
===================================================================
--- linux-2.6.orig/mm/fremap.c 2008-01-25 19:31:05.000000000 -0800
+++ linux-2.6/mm/fremap.c 2008-01-25 19:32:49.000000000 -0800
@@ -15,6 +15,7 @@
#include <linux/rmap.h>
#include <linux/module.h>
#include <linux/syscalls.h>
+#include <linux/mmu_notifier.h>

#include <asm/mmu_context.h>
#include <asm/cacheflush.h>
@@ -211,6 +212,7 @@ asmlinkage long sys_remap_file_pages(uns
spin_unlock(&mapping->i_mmap_lock);
}

+ mmu_notifier(invalidate_range, mm, start, start + size, 0);
err = populate_range(mm, vma, start, size, pgoff);
if (!err && !(flags & MAP_NONBLOCK)) {
if (unlikely(has_write_lock)) {
Index: linux-2.6/mm/memory.c
===================================================================
--- linux-2.6.orig/mm/memory.c 2008-01-25 19:31:05.000000000 -0800
+++ linux-2.6/mm/memory.c 2008-01-25 19:32:49.000000000 -0800
@@ -50,6 +50,7 @@
#include <linux/delayacct.h>
#include <linux/init.h>
#include <linux/writeback.h>
+#include <linux/mmu_notifier.h>

#include <asm/pgalloc.h>
#include <asm/uaccess.h>
@@ -891,6 +892,8 @@ unsigned long zap_page_range(struct vm_a
end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
if (tlb)
tlb_finish_mmu(tlb, address, end);
+ mmu_notifier(invalidate_range, mm, address, end,
+ (details ? (details->i_mmap_lock != NULL) : 0));
return end;
}

@@ -1319,7 +1322,7 @@ int remap_pfn_range(struct vm_area_struc
{
pgd_t *pgd;
unsigned long next;
- unsigned long end = addr + PAGE_ALIGN(size);
+ unsigned long start = addr, end = addr + PAGE_ALIGN(size);
struct mm_struct *mm = vma->vm_mm;
int err;

@@ -1360,6 +1363,7 @@ int remap_pfn_range(struct vm_area_struc
if (err)
break;
} while (pgd++, addr = next, addr != end);
+ mmu_notifier(invalidate_range, mm, start, end, 0);
return err;
}
EXPORT_SYMBOL(remap_pfn_range);
@@ -1443,7 +1447,7 @@ int apply_to_page_range(struct mm_struct
{
pgd_t *pgd;
unsigned long next;
- unsigned long end = addr + size;
+ unsigned long start = addr, end = addr + size;
int err;

BUG_ON(addr >= end);
@@ -1454,6 +1458,7 @@ int apply_to_page_range(struct mm_struct
if (err)
break;
} while (pgd++, addr = next, addr != end);
+ mmu_notifier(invalidate_range, mm, start, end, 0);
return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);
@@ -1634,6 +1639,8 @@ gotten:
/*
* Re-check the pte - we dropped the lock
*/
+ mmu_notifier(invalidate_range, mm, address,
+ address + PAGE_SIZE - 1, 0);
page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
if (likely(pte_same(*page_table, orig_pte))) {
if (old_page) {
Index: linux-2.6/mm/mmap.c
===================================================================
--- linux-2.6.orig/mm/mmap.c 2008-01-25 19:31:05.000000000 -0800
+++ linux-2.6/mm/mmap.c 2008-01-25 19:32:49.000000000 -0800
@@ -1748,6 +1748,7 @@ static void unmap_region(struct mm_struc
free_pgtables(&tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
next? next->vm_start: 0);
tlb_finish_mmu(tlb, start, end);
+ mmu_notifier(invalidate_range, mm, start, end, 0);
}

/*
Index: linux-2.6/mm/hugetlb.c
===================================================================
--- linux-2.6.orig/mm/hugetlb.c 2008-01-25 19:33:58.000000000 -0800
+++ linux-2.6/mm/hugetlb.c 2008-01-25 19:34:13.000000000 -0800
@@ -14,6 +14,7 @@
#include <linux/mempolicy.h>
#include <linux/cpuset.h>
#include <linux/mutex.h>
+#include <linux/mmu_notifier.h>

#include <asm/page.h>
#include <asm/pgtable.h>
@@ -763,6 +764,7 @@ void __unmap_hugepage_range(struct vm_ar
}
spin_unlock(&mm->page_table_lock);
flush_tlb_range(vma, start, end);
+ mmu_notifier(invalidate_range, mm, start, end, 1);
list_for_each_entry_safe(page, tmp, &page_list, lru) {
list_del(&page->lru);
put_page(page);
--


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