From 644210f3f890d1e5481378d28d150d1c5f4191fa Mon Sep 17 00:00:00 2001 From: =?utf8?q?Mika=20Penttil=C3=A4?= Date: Tue, 26 Jan 2016 15:47:25 +0000 Subject: [PATCH] UPSTREAM: arm64: mm: avoid calling apply_to_page_range on empty range MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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: Reviewed-by: Laura Abbott Acked-by: David Rientjes Signed-off-by: Mika Penttilä Signed-off-by: Will Deacon Bug: 30369029 Patchset: kaslr-arm64-4.4 (cherry picked from commit 57adec866c0440976c96a4b8f5b59fb411b1cacb) Signed-off-by: Jeff Vander Stoep Change-Id: Ia107d3b324cc8237f669778a7c9c3abae8637501 --- arch/arm64/mm/pageattr.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c index 29ee7d85ca4c..0795c3a36d8f 100644 --- a/arch/arm64/mm/pageattr.c +++ b/arch/arm64/mm/pageattr.c @@ -72,6 +72,9 @@ static int change_memory_common(unsigned long addr, int numpages, !(area->flags & VM_ALLOC)) return -EINVAL; + if (!numpages) + return 0; + data.set_mask = set_mask; data.clear_mask = clear_mask; -- 2.20.1