uprobes: Move alloc_page() from xol_add_vma() to xol_alloc_area()

Move alloc_page() from xol_add_vma() to xol_alloc_area() to cleanup
the code. This separates the memory allocations and consolidates the
-EALREADY cleanups and the error handling.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Anton Arapov <anton@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

1 files changed, 13 insertions, 19 deletions

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index f1b807831fc2..ea2e2a85479a 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1041,22 +1041,14 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon
 /* Slot allocation for XOL */
 static int xol_add_vma(struct xol_area *area)
 {
-        struct mm_struct *mm;
-        int ret;
-
-        area->page = alloc_page(GFP_HIGHUSER);
-        if (!area->page)
-                return -ENOMEM;
-
-        ret = -EALREADY;
-        mm = current->mm;
+        struct mm_struct *mm = current->mm;
+        int ret = -EALREADY;
 
         down_write(&mm->mmap_sem);
         if (mm->uprobes_state.xol_area)
                 goto fail;
 
         ret = -ENOMEM;
-
         /* Try to map as high as possible, this is only a hint. */
         area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, PAGE_SIZE, 0, 0);
         if (area->vaddr & ~PAGE_MASK) {
@@ -1072,11 +1064,8 @@ static int xol_add_vma(struct xol_area *area)
         smp_wmb();      /* pairs with get_xol_area() */
         mm->uprobes_state.xol_area = area;
         ret = 0;
-
-fail:
+ fail:
         up_write(&mm->mmap_sem);
-        if (ret)
-                __free_page(area->page);
 
         return ret;
 }
@@ -1104,21 +1093,26 @@ static struct xol_area *xol_alloc_area(void)
 
         area = kzalloc(sizeof(*area), GFP_KERNEL);
         if (unlikely(!area))
-                return NULL;
+                goto out;
 
         area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long), GFP_KERNEL);
-
         if (!area->bitmap)
-                goto fail;
+                goto free_area;
+
+        area->page = alloc_page(GFP_HIGHUSER);
+        if (!area->page)
+                goto free_bitmap;
 
         init_waitqueue_head(&area->wq);
         if (!xol_add_vma(area))
                 return area;
 
-fail:
+        __free_page(area->page);
+ free_bitmap:
         kfree(area->bitmap);
+ free_area:
         kfree(area);
-
+ out:
         return get_xol_area(current->mm);
 }