Patch "x86/mm/kasan: Don't use vmemmap_populate() to initialize shadow" has been added to the 4.14-stable tree

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

x86/mm/kasan: Don't use vmemmap_populate() to initialize shadow

to the 4.14-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:
x86-mm-kasan-don-t-use-vmemmap_populate-to-initialize-shadow.patch
and it can be found in the queue-4.14 subdirectory.

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

From: Andrey Ryabinin <[email protected]>
Date: Wed, 15 Nov 2017 17:36:35 -0800
Subject: x86/mm/kasan: Don't use vmemmap_populate() to initialize shadow

From: Andrey Ryabinin <[email protected]>

commit 2aeb07365bcd489620f71390a7d2031cd4dfb83e upstream.

[ Note, this is a Git cherry-pick of the following commit:

    d17a1d97dc20: ("x86/mm/kasan: don't use vmemmap_populate() to initialize shadow")

... for easier x86 PTI code testing and back-porting. ]

The KASAN shadow is currently mapped using vmemmap_populate() since that provides a semi-convenient way to map pages into init_top_pgt. However, since that no longer zeroes the mapped pages, it is not suitable for KASAN, which requires zeroed shadow memory.

Add kasan_populate_shadow() interface and use it instead of vmemmap_populate(). Besides, this allows us to take advantage of gigantic pages and use them to populate the shadow, which should save us some memory wasted on page tables and reduce TLB pressure.

---
 arch/x86/Kconfig            |    2 
 arch/x86/mm/kasan_init_64.c |  143 +++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 137 insertions(+), 8 deletions(-)

@@ -108,7 +108,7 @@ config X86
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
 	select HAVE_ARCH_JUMP_LABEL
-	select HAVE_ARCH_KASAN			if X86_64 && SPARSEMEM_VMEMMAP
+	select HAVE_ARCH_KASAN			if X86_64
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_KMEMCHECK
 	select HAVE_ARCH_MMAP_RND_BITS		if MMU

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

queue-4.14/x86-kasan-use-the-same-shadow-offset-for-4-and-5-level-paging.patch queue-4.14/x86-kasan-64-teach-kasan-about-the-cpu_entry_area.patch queue-4.14/x86-mm-kasan-don-t-use-vmemmap_populate-to-initialize-shadow.patch