Patch "sparc64: reset mm cpumask after wrap" has been added to the 4.11-stable tree

This is a note to let you know that I've just added the patch titled

sparc64: reset mm cpumask after wrap

to the 4.11-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:
sparc64-reset-mm-cpumask-after-wrap.patch
and it can be found in the queue-4.11 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Pavel Tatashin <[email protected]>
Date: Wed, 31 May 2017 11:25:20 -0400
Subject: sparc64: reset mm cpumask after wrap

From: Pavel Tatashin <[email protected]>

[ Upstream commit 588974857359861891f478a070b1dc7ae04a3880 ]

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

---
 arch/sparc/mm/init_64.c |    2 ++
 1 file changed, 2 insertions(+)

@@ -759,6 +759,8 @@ void get_new_mmu_context(struct mm_struc
 			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:

Patches currently in stable-queue which might be from [email protected] are

queue-4.11/sparc64-new-context-wrap.patch queue-4.11/sparc64-combine-activate_mm-and-switch_mm.patch queue-4.11/sparc64-add-per-cpu-mm-of-secondary-contexts.patch queue-4.11/sparc64-reset-mm-cpumask-after-wrap.patch queue-4.11/sparc64-redefine-first-version.patch queue-4.11/sparc64-delete-old-wrap-code.patch