Commit f33f76d2 authored by Paolo Pisati's avatar Paolo Pisati Committed by Tim Gardner

UBUNTU SAUCE: arm: mm: avoid calling apply_to_page_range on empty range

Calling apply_to_page_range with an empty range results in a BUG_ON
from the core code. This can be triggered by trying to load the st_drv
module with CONFIG_DEBUG_SET_MODULE_RONX enabled:

	kernel BUG at mm/memory.c:1874!
	Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
	Modules linked in:
	CPU: 3 PID: 1764 Comm: insmod Not tainted 4.5.0-rc1+ #2
	Hardware name: ARM Juno development board (r0) (DT)
	task: ffffffc9763b8000 ti: ffffffc975af8000 task.ti: ffffffc975af8000
	PC is at apply_to_page_range+0x2cc/0x2d0
	LR is at change_memory_common+0x80/0x108

This patch fixes the issue by making change_memory_common (called by the
set_memory_* functions) a NOP when numpages == 0, therefore avoiding the
erroneous call to apply_to_page_range and bringing us into line with x86
and s390.

Cc: <stable@vger.kernel.org>
Reviewed-by: default avatarLaura Abbott <labbott@redhat.com>
Acked-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarMika Penttilä <mika.penttila@nextfour.com>

BugLink: http://bugs.launchpad.net/bugs/1547718Signed-off-by: default avatarPaolo Pisati <paolo.pisati@canonical.com>
Acked-by: default avatarBrad Figg <brad.figg@canonical.com>
Acked-by: default avatarKamal Mostafa <kamal@canonical.com>
Signed-off-by: default avatarAndy Whitcroft <apw@canonical.com>
parent 8e5e3151
......@@ -55,6 +55,9 @@ static int change_memory_common(unsigned long addr, int numpages,
if (end < MODULES_VADDR || start >= MODULES_END)
return -EINVAL;
if (!numpages)
return 0;
data.set_mask = set_mask;
data.clear_mask = clear_mask;
......
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