A segmentation fault can occur in kimage_add_entry in kexec.c when
loading a kernel image into memory. The fault occurs because a page is
requested by calling kimage_alloc_page with gfp_mask GFP_KERNEL and the
function may actually return a page with gfp_mask GFP_HIGHUSER. The high
mem page is returned because it was swapped with the kernel page due to
the kernel page being a page that will shortly be copied to.
This patch ensures that kimage_alloc_page returns a page that was
created with the correct gfp flags.
--- linux-2.6.26.5.orig/kernel/kexec.c 2008-09-16 13:17:56.000000000
-0400
+++ linux-2.6.26.5/kernel/kexec.c 2008-09-16 13:26:35.000000000 -0400
@@ -743,8 +743,15 @@ static struct page *kimage_alloc_page(st
*old = addr | (*old & ~PAGE_MASK);
/* The old page I have found cannot be a
- * destination page, so return it.
- */
+ * destination page, so return it if its
+ * gfp_flags honor the ones passed in.
+ */
+ if (!(gfp_mask & __GFP_HIGHMEM) &&
+ PageHighMem(old_page)) {
+ kimage_free_pages(old_page);
+ continue;
+ }
+
addr = old_addr;
page = old_page;
break;
Signed-off-by: Jonathan Steel <jon.steel at esentire.com>
Jonathan Steel
