[PATCH 4.4 10/30] x86/mm/32: Set the __vmalloc_start_set flag in initmem_init()

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Laura Abbott <labbott@xxxxxxxxxx>

commit 861ce4a3244c21b0af64f880d5bfe5e6e2fb9e4a upstream.

'__vmalloc_start_set' currently only gets set in initmem_init() when
!CONFIG_NEED_MULTIPLE_NODES. This breaks detection of vmalloc address
with virt_addr_valid() with CONFIG_NEED_MULTIPLE_NODES=y, causing
a kernel crash:

  [mm/usercopy] 517e1fbeb6: kernel BUG at arch/x86/mm/physaddr.c:78!

Set '__vmalloc_start_set' appropriately for that case as well.

Reported-by: kbuild test robot <fengguang.wu@xxxxxxxxx>
Signed-off-by: Laura Abbott <labbott@xxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Fixes: dc16ecf7fd1f ("x86-32: use specific __vmalloc_start_set flag in __virt_addr_valid")
Link: http://lkml.kernel.org/r/1494278596-30373-1-git-send-email-labbott@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/x86/mm/numa_32.c |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/x86/mm/numa_32.c
+++ b/arch/x86/mm/numa_32.c
@@ -100,5 +100,6 @@ void __init initmem_init(void)
 	printk(KERN_DEBUG "High memory starts at vaddr %08lx\n",
 			(ulong) pfn_to_kaddr(highstart_pfn));
 
+	__vmalloc_start_set = true;
 	setup_bootmem_allocator();
 }