This is a note to let you know that I've just added the patch titled
arm64: Do not attempt to use init_mm in reset_context()
to the 4.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm64-do-not-attempt-to-use-init_mm-in-reset_context.patch
and it can be found in the queue-4.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 565630d503ef24e44c252bed55571b3a0d68455f Mon Sep 17 00:00:00 2001
From: Catalin Marinas <catalin.marinas@xxxxxxx>
Date: Fri, 12 Jun 2015 11:24:41 +0100
Subject: arm64: Do not attempt to use init_mm in reset_context()
From: Catalin Marinas <catalin.marinas@xxxxxxx>
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@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/mm/context.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- 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;
Patches currently in stable-queue which might be from catalin.marinas@xxxxxxx are
queue-4.1/arm64-do-not-attempt-to-use-init_mm-in-reset_context.patch
queue-4.1/mm-kmemleak-allow-safe-memory-scanning-during-kmemleak-disabling.patch
queue-4.1/arm64-entry-fix-context-tracking-for-el0_sp_pc.patch
queue-4.1/arm64-vdso-work-around-broken-elf-toolchains-in-makefile.patch
queue-4.1/mm-kmemleak_alloc_percpu-should-follow-the-gfp-from-per_alloc.patch
queue-4.1/arm64-mm-fix-freeing-of-the-wrong-memmap-entries-with-sparsemem_vmemmap.patch
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