From: Catalin Marinas Date: Fri, 12 Jun 2015 10:24:41 +0000 (+0100) Subject: arm64: Do not attempt to use init_mm in reset_context() X-Git-Tag: firefly_0821_release~176^2~1475^2~20 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=565630d503ef24e44c252bed55571b3a0d68455f;p=firefly-linux-kernel-4.4.55.git arm64: Do not attempt to use init_mm in reset_context() After secondary CPU boot or hotplug, the active_mm of the idle thread is &init_mm. The init_mm.pgd (swapper_pg_dir) is only meant for TTBR1_EL1 and must not be set in TTBR0_EL1. Since when active_mm == &init_mm the TTBR0_EL1 is already set to the reserved value, there is no need to perform any context reset. Signed-off-by: Catalin Marinas Cc: --- diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c index baa758d37021..76c1e6cd36fc 100644 --- a/arch/arm64/mm/context.c +++ b/arch/arm64/mm/context.c @@ -92,6 +92,14 @@ static void reset_context(void *info) unsigned int cpu = smp_processor_id(); struct mm_struct *mm = current->active_mm; + /* + * current->active_mm could be init_mm for the idle thread immediately + * after secondary CPU boot or hotplug. TTBR0_EL1 is already set to + * the reserved value, so no need to reset any context. + */ + if (mm == &init_mm) + return; + smp_rmb(); asid = cpu_last_asid + cpu;