linux-stable.git/arch/powerpc/include/asm/pgtable.h, branch linux-4.9.y

powerpc/mm: check for irq disabled() only if DEBUG_VM is enabled

2016-07-26T23:19:19+00:00

We don't need to check this always.  The idea here is to capture the
wrong usage of find_linux_pte_or_hugepte and we can do that by
occasionally running with DEBUG_VM enabled.

Link: http://lkml.kernel.org/r/1464692688-6612-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V 
Cc: Michael Ellerman 
Cc: Benjamin Herrenschmidt 
Reviewed-by: Anshuman Khandual 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

arch: fix has_transparent_hugepage()

2016-05-20T02:12:14+00:00

I've just discovered that the useful-sounding has_transparent_hugepage()
is actually an architecture-dependent minefield: on some arches it only
builds if CONFIG_TRANSPARENT_HUGEPAGE=y, on others it's also there when
not, but on some of those (arm and arm64) it then gives the wrong
answer; and on mips alone it's marked __init, which would crash if
called later (but so far it has not been called later).

Straighten this out: make it available to all configs, with a sensible
default in asm-generic/pgtable.h, removing its definitions from those
arches (arc, arm, arm64, sparc, tile) which are served by the default,
adding #define has_transparent_hugepage has_transparent_hugepage to
those (mips, powerpc, s390, x86) which need to override the default at
runtime, and removing the __init from mips (but maybe that kind of code
should be avoided after init: set a static variable the first time it's
called).

Signed-off-by: Hugh Dickins 
Cc: "Kirill A. Shutemov" 
Cc: Andrea Arcangeli 
Cc: Andres Lagar-Cavilla 
Cc: Yang Shi 
Cc: Ning Qu 
Cc: Mel Gorman 
Cc: Konstantin Khlebnikov 
Acked-by: David S. Miller 
Acked-by: Vineet Gupta 		[arch/arc]
Acked-by: Gerald Schaefer 	[arch/s390]
Acked-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

powerpc: Make vmalloc_to_phys() public

2016-02-16T02:44:26+00:00

This makes vmalloc_to_phys() public as there will be another user
(KVM in-kernel VFIO acceleration) for it soon. As this new user
can be compiled as a module, this exports the symbol.

As a little optimization, this changes the helper to call
vmalloc_to_pfn() instead of vmalloc_to_page() as the size of the
struct page may not be power-of-two aligned which will make gcc use
multiply instructions instead of shifts.

Signed-off-by: Alexey Kardashevskiy 
Acked-by: Michael Ellerman 
Reviewed-by: David Gibson 
Signed-off-by: Paul Mackerras

powerpc/booke: Move nohash headers

2015-12-14T04:19:09+00:00

Move the booke related headers below booke/32 or booke/64

Acked-by: Scott Wood 
Signed-off-by: Aneesh Kumar K.V 
Signed-off-by: Michael Ellerman

powerpc/mm: Move hash64 PTE bits from book3s/64/pgtable.h to hash.h

2015-12-14T04:19:08+00:00

This enables us to keep hash64 related bits together, and makes it easy
to follow.

Acked-by: Scott Wood 
Signed-off-by: Aneesh Kumar K.V 
Signed-off-by: Michael Ellerman

powerpc/mm: Don't have generic headers introduce functions touching pte bits

2015-12-14T04:19:06+00:00

We are going to drop pte_common.h in the later patch. The idea is to
enable hash code not require to define all PTE bits. Having PTE bits
defined in pte_common.h made the code unnecessarily complex.

Acked-by: Scott Wood 
Signed-off-by: Aneesh Kumar K.V 
Signed-off-by: Michael Ellerman

powerpc/mm: make a separate copy for book3s

2015-12-14T04:19:05+00:00

In this patch we do:
cp pgtable-ppc32.h book3s/32/pgtable.h
cp pgtable-ppc64.h book3s/64/pgtable.h

This enable us to do further changes to hash specific config.
We will change the page table format for 64bit hash in later patches.

Acked-by: Scott Wood 
Signed-off-by: Aneesh Kumar K.V 
Signed-off-by: Michael Ellerman

powerpc/mm: Differentiate between hugetlb and THP during page walk

2015-10-12T04:30:09+00:00

We need to properly identify whether a hugepage is an explicit or
a transparent hugepage in follow_huge_addr(). We used to depend
on hugepage shift argument to do that. But in some case that can
result in wrong results. For ex:

On finding a transparent hugepage we set hugepage shift to PMD_SHIFT.
But we can end up clearing the thp pte, via pmdp_huge_get_and_clear.
We do prevent reusing the pfn page via the usage of
kick_all_cpus_sync(). But that happens after we updated the pte to 0.
Hence in follow_huge_addr() we can find hugepage shift set, but transparent
huge page check fail for a thp pte.

NOTE: We fixed a variant of this race against thp split in commit
691e95fd7396905a38d98919e9c150dbc3ea21a3
("powerpc/mm/thp: Make page table walk safe against thp split/collapse")

Without this patch, we may hit the BUG_ON(flags & FOLL_GET) in
follow_page_mask occasionally.

In the long term, we may want to switch ppc64 64k page size config to
enable CONFIG_ARCH_WANT_GENERAL_HUGETLB

Reported-by: David Gibson 
Signed-off-by: Aneesh Kumar K.V 
Signed-off-by: Michael Ellerman

powerpc/booke64: Move mb() to __set_pte_at() with kernel-addr test

2015-08-08T04:00:01+00:00

map_kernel() doesn't catch all places that create kernel PTEs.  In
particular, vmalloc() calls set_pte_at() directly.  This causes a
crash when booting a non-SMP kernel on e6500.

Move the sync to __set_pte(), to be executed only for kernel addresses.

Signed-off-by: Scott Wood

powerpc/mm/thp: Make page table walk safe against thp split/collapse

2015-04-17T01:23:39+00:00

We can disable a THP split or a hugepage collapse by disabling irq.
We do send IPI to all the cpus in the early part of split/collapse,
and disabling local irq ensure we don't make progress with
split/collapse. If the THP is getting split we return NULL from
find_linux_pte_or_hugepte(). For all the current callers it should be ok.
We need to be careful if we want to use returned pte_t pointer outside
the irq disabled region. W.r.t to THP split, the pfn remains the same,
but then a hugepage collapse will result in a pfn change. There are
few steps we can take to avoid a hugepage collapse.One way is to take page
reference inside the irq disable region. Other option is to take
mmap_sem so that a parallel collapse will not happen. We can also
disable collapse by taking pmd_lock. Another method used by kvm
subsystem is to check whether we had a mmu_notifer update in between
using mmu_notifier_retry().

Signed-off-by: Aneesh Kumar K.V 
Signed-off-by: Michael Ellerman