mm: zero out the vma in vma_init()

Rather than in vm_area_alloc(). To ensure that the various oddball stack-based vmas are in a good state. Some of the callers were zeroing them out, others were not. Acked-by: Kirill A. Shutemov <[email protected]> Cc: Russell King <[email protected]> Cc: Dmitry Vyukov <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Andrea Arcangeli <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
tadfisher · Aug 22, 2018 · a670468 · a670468
1 parent a3bf6ce
commit a670468
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Showing 6 changed files with 7 additions and 10 deletions.
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
@@ -330,16 +330,15 @@ unsigned long arch_randomize_brk(struct mm_struct *mm)
  * atomic helpers. Insert it into the gate_vma so that it is visible
  * through ptrace and /proc/<pid>/mem.
  */
-static struct vm_area_struct gate_vma = {
-	.vm_start	= 0xffff0000,
-	.vm_end		= 0xffff0000 + PAGE_SIZE,
-	.vm_flags	= VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYEXEC,
-};
+static struct vm_area_struct gate_vma;
 
 static int __init gate_vma_init(void)
 {
 	vma_init(&gate_vma, NULL);
 	gate_vma.vm_page_prot = PAGE_READONLY_EXEC;
+	gate_vma.vm_start = 0xffff0000;
+	gate_vma.vm_end	= 0xffff0000 + PAGE_SIZE;
+	gate_vma.vm_flags = VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYEXEC;
 	return 0;
 }
 arch_initcall(gate_vma_init);

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
@@ -410,7 +410,6 @@ static void remove_inode_hugepages(struct inode *inode, loff_t lstart,
 	int i, freed = 0;
 	bool truncate_op = (lend == LLONG_MAX);
 
-	memset(&pseudo_vma, 0, sizeof(struct vm_area_struct));
 	vma_init(&pseudo_vma, current->mm);
 	pseudo_vma.vm_flags = (VM_HUGETLB | VM_MAYSHARE | VM_SHARED);
 	pagevec_init(&pvec);
@@ -595,7 +594,6 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
 	 * allocation routines.  If NUMA is configured, use page index
 	 * as input to create an allocation policy.
 	 */
-	memset(&pseudo_vma, 0, sizeof(struct vm_area_struct));
 	vma_init(&pseudo_vma, mm);
 	pseudo_vma.vm_flags = (VM_HUGETLB | VM_MAYSHARE | VM_SHARED);
 	pseudo_vma.vm_file = file;

diff --git a/include/linux/mm.h b/include/linux/mm.h
@@ -456,6 +456,7 @@ static inline void vma_init(struct vm_area_struct *vma, struct mm_struct *mm)
 {
 	static const struct vm_operations_struct dummy_vm_ops = {};
 
+	memset(vma, 0, sizeof(*vma));
 	vma->vm_mm = mm;
 	vma->vm_ops = &dummy_vm_ops;
 	INIT_LIST_HEAD(&vma->anon_vma_chain);

diff --git a/kernel/fork.c b/kernel/fork.c
@@ -310,8 +310,9 @@ static struct kmem_cache *mm_cachep;
 
 struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
 {
-	struct vm_area_struct *vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+	struct vm_area_struct *vma;
 
+	vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
 	if (vma)
 		vma_init(vma, mm);
 	return vma;

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
@@ -2504,7 +2504,6 @@ void mpol_shared_policy_init(struct shared_policy *sp, struct mempolicy *mpol)
 			goto put_new;
 
 		/* Create pseudo-vma that contains just the policy */
-		memset(&pvma, 0, sizeof(struct vm_area_struct));
 		vma_init(&pvma, NULL);
 		pvma.vm_end = TASK_SIZE;	/* policy covers entire file */
 		mpol_set_shared_policy(sp, &pvma, new); /* adds ref */

diff --git a/mm/shmem.c b/mm/shmem.c
@@ -1421,7 +1421,6 @@ static void shmem_pseudo_vma_init(struct vm_area_struct *vma,
 		struct shmem_inode_info *info, pgoff_t index)
 {
 	/* Create a pseudo vma that just contains the policy */
-	memset(vma, 0, sizeof(*vma));
 	vma_init(vma, NULL);
 	/* Bias interleave by inode number to distribute better across nodes */
 	vma->vm_pgoff = index + info->vfs_inode.i_ino;