[Xenial PATCH 2/3] UBUNTU: SAUCE: s390/mm: fix local TLB flushing vs. detach of an mm address space
Stefan Bader
stefan.bader at canonical.com
Tue Sep 12 09:45:39 UTC 2017
From: Martin Schwidefsky <schwidefsky at de.ibm.com>
BugLink: http://bugs.launchpad.net/bugs/1708399
The local TLB flushing code keeps an additional mask in the mm.context,
the cpu_attach_mask. At the time a global flush of an address space is
done the cpu_attach_mask is copied to the mm_cpumask in order to avoid
future global flushes in case the mm is used by a single CPU only after
the flush.
Trouble is that the reset of the mm_cpumask is racy against the detach
of an mm address space by switch_mm. The current order is first the
global TLB flush and then the copy of the cpu_attach_mask to the
mm_cpumask. The order needs to be the other way around.
Cc: <stable at vger.kernel.org>
Reviewed-by: Heiko Carstens <heiko.carstens at de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky at de.ibm.com>
(backported from b3e5dc45fd1ec2aa1de6b80008f9295eb17e0659 linux-next)
[merged with "s390/mm,kvm: flush gmap address space with IDTE"]
Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
---
arch/s390/include/asm/tlbflush.h | 56 ++++++++++++----------------------------
1 file changed, 16 insertions(+), 40 deletions(-)
diff --git a/arch/s390/include/asm/tlbflush.h b/arch/s390/include/asm/tlbflush.h
index 80868c84..d54cc83 100644
--- a/arch/s390/include/asm/tlbflush.h
+++ b/arch/s390/include/asm/tlbflush.h
@@ -47,47 +47,31 @@ static inline void __tlb_flush_global(void)
}
/*
- * Flush TLB entries for a specific mm on all CPUs (in case gmap is used
- * this implicates multiple ASCEs!).
+ * Flush TLB entries for a specific ASCE on all CPUs.
*/
-static inline void __tlb_flush_full(struct mm_struct *mm)
+static inline void __tlb_flush_mm(struct mm_struct * mm)
{
+ /*
+ * If the machine has IDTE we prefer to do a per mm flush
+ * on all cpus instead of doing a local flush if the mm
+ * only ran on the local cpu.
+ */
preempt_disable();
atomic_add(0x10000, &mm->context.attach_count);
- if (cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id()))) {
- /* Local TLB flush */
- __tlb_flush_local();
+ /* Reset TLB flush mask */
+ if (MACHINE_HAS_TLB_LC)
+ cpumask_copy(mm_cpumask(mm), &mm->context.cpu_attach_mask);
+ barrier();
+ if (MACHINE_HAS_IDTE && list_empty(&mm->context.gmap_list)) {
+ __tlb_flush_idte(mm->context.asce);
} else {
/* Global TLB flush */
__tlb_flush_global();
- /* Reset TLB flush mask */
- if (MACHINE_HAS_TLB_LC)
- cpumask_copy(mm_cpumask(mm),
- &mm->context.cpu_attach_mask);
}
atomic_sub(0x10000, &mm->context.attach_count);
preempt_enable();
}
-/*
- * Flush TLB entries for a specific ASCE on all CPUs. Should never be used
- * when more than one asce (e.g. gmap) ran on this mm.
- */
-static inline void __tlb_flush_asce(struct mm_struct *mm, unsigned long asce)
-{
- preempt_disable();
- atomic_add(0x10000, &mm->context.attach_count);
- if (MACHINE_HAS_IDTE)
- __tlb_flush_idte(asce);
- else
- __tlb_flush_global();
- /* Reset TLB flush mask */
- if (MACHINE_HAS_TLB_LC)
- cpumask_copy(mm_cpumask(mm), &mm->context.cpu_attach_mask);
- atomic_sub(0x10000, &mm->context.attach_count);
- preempt_enable();
-}
-
static inline void __tlb_flush_kernel(void)
{
if (MACHINE_HAS_IDTE)
@@ -97,7 +81,6 @@ static inline void __tlb_flush_kernel(void)
}
#else
#define __tlb_flush_global() __tlb_flush_local()
-#define __tlb_flush_full(mm) __tlb_flush_local()
/*
* Flush TLB entries for a specific ASCE on all CPUs.
@@ -111,21 +94,14 @@ static inline void __tlb_flush_kernel(void)
{
__tlb_flush_local();
}
-#endif
static inline void __tlb_flush_mm(struct mm_struct * mm)
{
- /*
- * If the machine has IDTE we prefer to do a per mm flush
- * on all cpus instead of doing a local flush if the mm
- * only ran on the local cpu.
- */
- if (MACHINE_HAS_IDTE && list_empty(&mm->context.gmap_list))
- __tlb_flush_asce(mm, mm->context.asce);
- else
- __tlb_flush_full(mm);
+ __tlb_flush_local();
}
+#endif
+
static inline void __tlb_flush_mm_lazy(struct mm_struct * mm)
{
if (mm->context.flush_mm) {
--
2.7.4
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