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authorLinus Torvalds <torvalds@linux-foundation.org>2012-03-21 13:32:19 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-21 13:32:19 -0700
commit3a990a52f9f25f45469e272017a31e7a3fda60ed (patch)
tree366f639d9ce1e907b65caa72bc098df6c4b5a240
parent3556485f1595e3964ba539e39ea682acbb835cee (diff)
parentf5cc4eef9987d0b517364d01e290d6438e47ee5d (diff)
Merge branch 'vm' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull munmap/truncate race fixes from Al Viro: "Fixes for racy use of unmap_vmas() on truncate-related codepaths" * 'vm' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: VM: make zap_page_range() callers that act on a single VMA use separate helper VM: make unmap_vmas() return void VM: don't bother with feeding upper limit to tlb_finish_mmu() in exit_mmap() VM: make zap_page_range() return void VM: can't go through the inner loop in unmap_vmas() more than once... VM: unmap_page_range() can return void
-rw-r--r--include/linux/mm.h4
-rw-r--r--mm/memory.c133
-rw-r--r--mm/mmap.c5
3 files changed, 84 insertions, 58 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 17b27cd269c..b5bb54d6d66 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -893,9 +893,9 @@ struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
unsigned long size);
-unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
+void zap_page_range(struct vm_area_struct *vma, unsigned long address,
unsigned long size, struct zap_details *);
-unsigned long unmap_vmas(struct mmu_gather *tlb,
+void unmap_vmas(struct mmu_gather *tlb,
struct vm_area_struct *start_vma, unsigned long start_addr,
unsigned long end_addr, unsigned long *nr_accounted,
struct zap_details *);
diff --git a/mm/memory.c b/mm/memory.c
index 347e5fad1cf..8438c157e4d 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1282,10 +1282,10 @@ static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
return addr;
}
-static unsigned long unmap_page_range(struct mmu_gather *tlb,
- struct vm_area_struct *vma,
- unsigned long addr, unsigned long end,
- struct zap_details *details)
+static void unmap_page_range(struct mmu_gather *tlb,
+ struct vm_area_struct *vma,
+ unsigned long addr, unsigned long end,
+ struct zap_details *details)
{
pgd_t *pgd;
unsigned long next;
@@ -1305,8 +1305,47 @@ static unsigned long unmap_page_range(struct mmu_gather *tlb,
} while (pgd++, addr = next, addr != end);
tlb_end_vma(tlb, vma);
mem_cgroup_uncharge_end();
+}
- return addr;
+
+static void unmap_single_vma(struct mmu_gather *tlb,
+ struct vm_area_struct *vma, unsigned long start_addr,
+ unsigned long end_addr, unsigned long *nr_accounted,
+ struct zap_details *details)
+{
+ unsigned long start = max(vma->vm_start, start_addr);
+ unsigned long end;
+
+ if (start >= vma->vm_end)
+ return;
+ end = min(vma->vm_end, end_addr);
+ if (end <= vma->vm_start)
+ return;
+
+ if (vma->vm_flags & VM_ACCOUNT)
+ *nr_accounted += (end - start) >> PAGE_SHIFT;
+
+ if (unlikely(is_pfn_mapping(vma)))
+ untrack_pfn_vma(vma, 0, 0);
+
+ if (start != end) {
+ if (unlikely(is_vm_hugetlb_page(vma))) {
+ /*
+ * It is undesirable to test vma->vm_file as it
+ * should be non-null for valid hugetlb area.
+ * However, vm_file will be NULL in the error
+ * cleanup path of do_mmap_pgoff. When
+ * hugetlbfs ->mmap method fails,
+ * do_mmap_pgoff() nullifies vma->vm_file
+ * before calling this function to clean up.
+ * Since no pte has actually been setup, it is
+ * safe to do nothing in this case.
+ */
+ if (vma->vm_file)
+ unmap_hugepage_range(vma, start, end, NULL);
+ } else
+ unmap_page_range(tlb, vma, start, end, details);
+ }
}
/**
@@ -1318,8 +1357,6 @@ static unsigned long unmap_page_range(struct mmu_gather *tlb,
* @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
* @details: details of nonlinear truncation or shared cache invalidation
*
- * Returns the end address of the unmapping (restart addr if interrupted).
- *
* Unmap all pages in the vma list.
*
* Only addresses between `start' and `end' will be unmapped.
@@ -1331,55 +1368,18 @@ static unsigned long unmap_page_range(struct mmu_gather *tlb,
* ensure that any thus-far unmapped pages are flushed before unmap_vmas()
* drops the lock and schedules.
*/
-unsigned long unmap_vmas(struct mmu_gather *tlb,
+void unmap_vmas(struct mmu_gather *tlb,
struct vm_area_struct *vma, unsigned long start_addr,
unsigned long end_addr, unsigned long *nr_accounted,
struct zap_details *details)
{
- unsigned long start = start_addr;
struct mm_struct *mm = vma->vm_mm;
mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
- for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
- unsigned long end;
-
- start = max(vma->vm_start, start_addr);
- if (start >= vma->vm_end)
- continue;
- end = min(vma->vm_end, end_addr);
- if (end <= vma->vm_start)
- continue;
-
- if (vma->vm_flags & VM_ACCOUNT)
- *nr_accounted += (end - start) >> PAGE_SHIFT;
-
- if (unlikely(is_pfn_mapping(vma)))
- untrack_pfn_vma(vma, 0, 0);
-
- while (start != end) {
- if (unlikely(is_vm_hugetlb_page(vma))) {
- /*
- * It is undesirable to test vma->vm_file as it
- * should be non-null for valid hugetlb area.
- * However, vm_file will be NULL in the error
- * cleanup path of do_mmap_pgoff. When
- * hugetlbfs ->mmap method fails,
- * do_mmap_pgoff() nullifies vma->vm_file
- * before calling this function to clean up.
- * Since no pte has actually been setup, it is
- * safe to do nothing in this case.
- */
- if (vma->vm_file)
- unmap_hugepage_range(vma, start, end, NULL);
-
- start = end;
- } else
- start = unmap_page_range(tlb, vma, start, end, details);
- }
- }
-
+ for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
+ unmap_single_vma(tlb, vma, start_addr, end_addr, nr_accounted,
+ details);
mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
- return start; /* which is now the end (or restart) address */
}
/**
@@ -1388,8 +1388,34 @@ unsigned long unmap_vmas(struct mmu_gather *tlb,
* @address: starting address of pages to zap
* @size: number of bytes to zap
* @details: details of nonlinear truncation or shared cache invalidation
+ *
+ * Caller must protect the VMA list
+ */
+void zap_page_range(struct vm_area_struct *vma, unsigned long address,
+ unsigned long size, struct zap_details *details)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ struct mmu_gather tlb;
+ unsigned long end = address + size;
+ unsigned long nr_accounted = 0;
+
+ lru_add_drain();
+ tlb_gather_mmu(&tlb, mm, 0);
+ update_hiwater_rss(mm);
+ unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
+ tlb_finish_mmu(&tlb, address, end);
+}
+
+/**
+ * zap_page_range_single - remove user pages in a given range
+ * @vma: vm_area_struct holding the applicable pages
+ * @address: starting address of pages to zap
+ * @size: number of bytes to zap
+ * @details: details of nonlinear truncation or shared cache invalidation
+ *
+ * The range must fit into one VMA.
*/
-unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
+static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
unsigned long size, struct zap_details *details)
{
struct mm_struct *mm = vma->vm_mm;
@@ -1400,9 +1426,10 @@ unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
lru_add_drain();
tlb_gather_mmu(&tlb, mm, 0);
update_hiwater_rss(mm);
- end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
+ mmu_notifier_invalidate_range_start(mm, address, end);
+ unmap_single_vma(&tlb, vma, address, end, &nr_accounted, details);
+ mmu_notifier_invalidate_range_end(mm, address, end);
tlb_finish_mmu(&tlb, address, end);
- return end;
}
/**
@@ -1423,7 +1450,7 @@ int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
if (address < vma->vm_start || address + size > vma->vm_end ||
!(vma->vm_flags & VM_PFNMAP))
return -1;
- zap_page_range(vma, address, size, NULL);
+ zap_page_range_single(vma, address, size, NULL);
return 0;
}
EXPORT_SYMBOL_GPL(zap_vma_ptes);
@@ -2770,7 +2797,7 @@ static void unmap_mapping_range_vma(struct vm_area_struct *vma,
unsigned long start_addr, unsigned long end_addr,
struct zap_details *details)
{
- zap_page_range(vma, start_addr, end_addr - start_addr, details);
+ zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
}
static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
diff --git a/mm/mmap.c b/mm/mmap.c
index 39a68ddf38b..6f3766b5780 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2237,7 +2237,6 @@ void exit_mmap(struct mm_struct *mm)
struct mmu_gather tlb;
struct vm_area_struct *vma;
unsigned long nr_accounted = 0;
- unsigned long end;
/* mm's last user has gone, and its about to be pulled down */
mmu_notifier_release(mm);
@@ -2262,11 +2261,11 @@ void exit_mmap(struct mm_struct *mm)
tlb_gather_mmu(&tlb, mm, 1);
/* update_hiwater_rss(mm) here? but nobody should be looking */
/* Use -1 here to ensure all VMAs in the mm are unmapped */
- end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
+ unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
vm_unacct_memory(nr_accounted);
free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
- tlb_finish_mmu(&tlb, 0, end);
+ tlb_finish_mmu(&tlb, 0, -1);
/*
* Walk the list again, actually closing and freeing it,