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arm64: mm: avoid calling apply_to_page_range on empty range

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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: Laura Abbott <labbott@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Mika Penttilä <mika.penttila@nextfour.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Mika Penttilä 2016-01-26 15:47:25 +00:00 committed by Will Deacon
parent 531d306731
commit 57adec866c
1 changed files with 3 additions and 0 deletions
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arch/arm64/mm/pageattr.c
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@ -57,6 +57,9 @@ static int change_memory_common(unsigned long addr, int numpages,
if (end < MODULES_VADDR || end >= MODULES_END)
return -EINVAL;
if (!numpages)
return 0;
data.set_mask = set_mask;
data.clear_mask = clear_mask;