sparc64: reset mm cpumask after wrap

After a wrap (getting a new context version) a process must get a new
context id, which means that we would need to flush the context id from
the TLB before running for the first time with this ID on every CPU. But,
we use mm_cpumask to determine if this process has been running on this CPU
before, and this mask is not reset after a wrap. So, there are two possible
fixes for this issue:

1. Clear mm cpumask whenever mm gets a new context id
2. Unconditionally flush context every time process is running on a CPU

This patch implements the first solution

Orabug: 25999953

Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Bob Picco <bob.picco@oracle.com>
Reviewed-by: Steven Sistare <steven.sistare@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 588974857359861891f478a070b1dc7ae04a3880)
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Steven Sistare <steven.sistare@oracle.com>
Signed-off-by: Allen Pais <allen.pais@oracle.com>

diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
index 0e42c840cb32c19f63aa1b3b823671a48d2eb061..c29074e31236a3dded8651565d7dea086c67e4b3 100644 (file)
--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -903,6 +903,8 @@ void get_new_mmu_context(struct mm_struct *mm)
                        goto out;
                }
        }
+       if (mm->context.sparc64_ctx_val)
+               cpumask_clear(mm_cpumask(mm));
        mmu_context_bmap[new_ctx>>6] |= (1UL << (new_ctx & 63));
        new_ctx |= (tlb_context_cache & CTX_VERSION_MASK);
 out: