linux-kernel - [PATCH 3.2 003/102] percpu: perform tlb flush after pcpu_map

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Message-ID: <lsq.1414880883.196823889@decadent.org.uk>
Date:	Sat, 01 Nov 2014 22:28:03 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Tejun Heo" <tj@...nel.org>
Subject: [PATCH 3.2 003/102] percpu: perform tlb flush after
 pcpu_map_pages() failure

3.2.64-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Tejun Heo <tj@...nel.org>

commit 849f5169097e1ba35b90ac9df76b5bb6f9c0aabd upstream.

If pcpu_map_pages() fails midway, it unmaps the already mapped pages.
Currently, it doesn't flush tlb after the partial unmapping.  This may
be okay in most cases as the established mapping hasn't been used at
that point but it can go wrong and when it goes wrong it'd be
extremely difficult to track down.

Flush tlb after the partial unmapping.

Signed-off-by: Tejun Heo <tj@...nel.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 mm/percpu-vm.c | 1 +
 1 file changed, 1 insertion(+)

--- a/mm/percpu-vm.c
+++ b/mm/percpu-vm.c
@@ -273,6 +273,7 @@ err:
 		__pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_start),
 				   page_end - page_start);
 	}
+	pcpu_post_unmap_tlb_flush(chunk, page_start, page_end);
 	return err;
 }
 

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