| Message ID | 1437008449-1864-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c index baa758d..76c1e6c 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;
This is a note to let you know that I have just added a patch titled arm64: Do not attempt to use init_mm in reset_context() to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue This patch is scheduled to be released in version 3.19.y-ckt4. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.19.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 460763cd960ebea3bf6818f2cc6b807615806431 Mon Sep 17 00:00:00 2001 From: Catalin Marinas <catalin.marinas@arm.com> Date: Fri, 12 Jun 2015 11:24:41 +0100 Subject: arm64: Do not attempt to use init_mm in reset_context() commit 565630d503ef24e44c252bed55571b3a0d68455f upstream. 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 <catalin.marinas@arm.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- arch/arm64/mm/context.c | 8 ++++++++ 1 file changed, 8 insertions(+) -- 1.9.1