Patch "arm64: kasan: avoid bad virt_to_pfn()" 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

arm64: kasan: avoid bad virt_to_pfn()

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:
arm64-kasan-avoid-bad-virt_to_pfn.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: Mark Rutland <[email protected]>
Date: Mon, 6 Mar 2017 19:06:40 +0000
Subject: arm64: kasan: avoid bad virt_to_pfn()

From: Mark Rutland <[email protected]>

[ Upstream commit b0de0ccc8b9edd8846828e0ecdc35deacdf186b0 ]

Booting a v4.11-rc1 kernel with DEBUG_VIRTUAL and KASAN enabled produces the following splat (trimmed for brevity):

[    0.000000] virt_to_phys used for non-linear address: ffff200008080000 (0xffff200008080000)
[    0.000000] WARNING: CPU: 0 PID: 0 at arch/arm64/mm/physaddr.c:14 __virt_to_phys+0x48/0x70
[    0.000000] PC is at __virt_to_phys+0x48/0x70
[    0.000000] LR is at __virt_to_phys+0x48/0x70
[    0.000000] Call trace:
[    0.000000] [<ffff2000080b1ac0>] __virt_to_phys+0x48/0x70
[    0.000000] [<ffff20000a03b86c>] kasan_init+0x1c0/0x498
[    0.000000] [<ffff20000a034018>] setup_arch+0x2fc/0x948
[    0.000000] [<ffff20000a030c68>] start_kernel+0xb8/0x570
[    0.000000] [<ffff20000a0301e8>] __primary_switched+0x6c/0x74

This is because we use virt_to_pfn() on a kernel image address when trying to figure out its nid, so that we can allocate its shadow from the same node.

As with other recent changes, this patch uses lm_alias() to solve this.

We could instead use NUMA_NO_NODE, as x86 does for all shadow allocations, though we'll likely want the "real" memory shadow to be backed from its corresponding nid anyway, so we may as well be consistent and find the nid for the image shadow.

---
 arch/arm64/mm/kasan_init.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -153,7 +153,7 @@ void __init kasan_init(void)
 	clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
 
 	vmemmap_populate(kimg_shadow_start, kimg_shadow_end,
-			 pfn_to_nid(virt_to_pfn(_text)));
+			 pfn_to_nid(virt_to_pfn(lm_alias(_text))));
 
 	/*
 	 * vmemmap_populate() has populated the shadow region that covers the

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

queue-4.9/arm64-kasan-avoid-bad-virt_to_pfn.patch