From: Mika Penttilä Date: Tue, 26 Jan 2016 15:47:25 +0000 (+0000) Subject: arm64: mm: avoid calling apply_to_page_range on empty range X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=57adec866c0440976c96a4b8f5b59fb411b1cacb;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git arm64: 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: Reviewed-by: Laura Abbott Acked-by: David Rientjes Signed-off-by: Mika Penttilä Signed-off-by: Will Deacon --- diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c index 3571c7309c5e..cf6240741134 100644 --- a/arch/arm64/mm/pageattr.c +++ b/arch/arm64/mm/pageattr.c @@ -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;