From 524e17d92bb1365e9bede9e1568b6fa4041db381 Mon Sep 17 00:00:00 2001 From: Paolo Pisati Date: Mon, 22 Feb 2016 13:12:24 +0100 Subject: [PATCH] UBUNTU SAUCE: arm: mm: avoid calling apply_to_page_range on empty range MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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: Paolo Pisati --- arch/arm/mm/pageattr.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arm/mm/pageattr.c b/arch/arm/mm/pageattr.c index cf30daf..4e59379 100644 --- a/arch/arm/mm/pageattr.c +++ b/arch/arm/mm/pageattr.c @@ -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; -- 2.7.0