Patch "sparc64: Zero pages on allocation for mondo and error queues." has been added to the 4.9-stable tree

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

sparc64: Zero pages on allocation for mondo and error queues.

to the 4.9-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-zero-pages-on-allocation-for-mondo-and-error-queues.patch
and it can be found in the queue-4.9 subdirectory.

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

From: "Liam R. Howlett" <[email protected]>
Date: Tue, 23 May 2017 21:54:11 -0400
Subject: sparc64: Zero pages on allocation for mondo and error queues.

From: "Liam R. Howlett" <[email protected]>

[ Upstream commit 7a7dc961a28b965a0d0303c2e989df17b411708b ]

Error queues use a non-zero first word to detect if the queues are full. Using pages that have not been zeroed may result in false positive overflow events. These queues are set up once during boot so zeroing all mondo and error queue pages is safe.

Note that the false positive overflow does not always occur because the page allocation for these queues is so early in the boot cycle that higher number CPUs get fresh pages. It is only when traps are serviced with lower number CPUs who were given already used pages that this issue is exposed.

---
 arch/sparc/kernel/irq_64.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -1021,7 +1021,7 @@ static void __init alloc_one_queue(unsig
 	unsigned long order = get_order(size);
 	unsigned long p;
 
-	p = __get_free_pages(GFP_KERNEL, order);
+	p = __get_free_pages(GFP_KERNEL | __GFP_ZERO, order);
 	if (!p) {
 		prom_printf("SUN4V: Error, cannot allocate queue.\n");
 		prom_halt();

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

queue-4.9/sparc64-handle-pio-mem-non-resumable-errors.patch queue-4.9/sparc64-zero-pages-on-allocation-for-mondo-and-error-queues.patch