[ 3.8.y.z extended stable ] Patch "sparc: tsb must be flushed before tlb" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    sparc: tsb must be flushed before tlb

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.6.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 62abbb78c107e28874b60768dd7ee29c76e5f84d Mon Sep 17 00:00:00 2001
From: Dave Kleikamp <dave.kleikamp at oracle.com>
Date: Tue, 18 Jun 2013 09:05:36 -0500
Subject: sparc: tsb must be flushed before tlb

commit 23a01138efe216f8084cfaa74b0b90dd4b097441 upstream.

This fixes a race where a cpu may re-load a tlb from a stale tsb right
after it has been flushed by a remote function call.

I still see some instability when stressing the system with parallel
kernel builds while creating memory pressure by writing to
/proc/sys/vm/nr_hugepages, but this patch improves the stability
significantly.

Signed-off-by: Dave Kleikamp <dave.kleikamp at oracle.com>
Acked-by: Bob Picco <bob.picco at oracle.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 arch/sparc/mm/tlb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/sparc/mm/tlb.c b/arch/sparc/mm/tlb.c
index 83d89bc..37e7bc4 100644
--- a/arch/sparc/mm/tlb.c
+++ b/arch/sparc/mm/tlb.c
@@ -85,8 +85,8 @@ static void tlb_batch_add_one(struct mm_struct *mm, unsigned long vaddr,
 	}

 	if (!tb->active) {
-		global_flush_tlb_page(mm, vaddr);
 		flush_tsb_user_page(mm, vaddr);
+		global_flush_tlb_page(mm, vaddr);
 		goto out;
 	}

--
1.8.1.2