linux-stable.git/include/linux/mm.h, branch v3.17.8

mm: page-writeback: inline account_page_dirtied() into single caller

2014-11-14T18:10:36+00:00

commit 3a3c02ecf7f2852f122d6d16fb9b3d9cb0c6f201 upstream.

A follow-up patch would have changed the call signature.  To save the
trouble, just fold it instead.

Signed-off-by: Johannes Weiner 
Acked-by: Michal Hocko 
Cc: Vladimir Davydov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

vfs: fix data corruption when blocksize < pagesize for mmaped data

2014-11-14T18:10:23+00:00

commit 90a8020278c1598fafd071736a0846b38510309c upstream.

->page_mkwrite() is used by filesystems to allocate blocks under a page
which is becoming writeably mmapped in some process' address space. This
allows a filesystem to return a page fault if there is not enough space
available, user exceeds quota or similar problem happens, rather than
silently discarding data later when writepage is called.

However VFS fails to call ->page_mkwrite() in all the cases where
filesystems need it when blocksize < pagesize. For example when
blocksize = 1024, pagesize = 4096 the following is problematic:
  ftruncate(fd, 0);
  pwrite(fd, buf, 1024, 0);
  map = mmap(NULL, 1024, PROT_WRITE, MAP_SHARED, fd, 0);
  map[0] = 'a';       ----> page_mkwrite() for index 0 is called
  ftruncate(fd, 10000); /* or even pwrite(fd, buf, 1, 10000) */
  mremap(map, 1024, 10000, 0);
  map[4095] = 'a';    ----> no page_mkwrite() called

At the moment ->page_mkwrite() is called, filesystem can allocate only
one block for the page because i_size == 1024. Otherwise it would create
blocks beyond i_size which is generally undesirable. But later at
->writepage() time, we also need to store data at offset 4095 but we
don't have block allocated for it.

This patch introduces a helper function filesystems can use to have
->page_mkwrite() called at all the necessary moments.

Signed-off-by: Jan Kara 
Signed-off-by: Theodore Ts'o 
Signed-off-by: Greg Kroah-Hartman

mm/balloon_compaction: redesign ballooned pages management

2014-10-30T16:43:15+00:00

commit d6d86c0a7f8ddc5b38cf089222cb1d9540762dc2 upstream.

Sasha Levin reported KASAN splash inside isolate_migratepages_range().
Problem is in the function __is_movable_balloon_page() which tests
AS_BALLOON_MAP in page->mapping->flags.  This function has no protection
against anonymous pages.  As result it tried to check address space flags
inside struct anon_vma.

Further investigation shows more problems in current implementation:

* Special branch in __unmap_and_move() never works:
  balloon_page_movable() checks page flags and page_count.  In
  __unmap_and_move() page is locked, reference counter is elevated, thus
  balloon_page_movable() always fails.  As a result execution goes to the
  normal migration path.  virtballoon_migratepage() returns
  MIGRATEPAGE_BALLOON_SUCCESS instead of MIGRATEPAGE_SUCCESS,
  move_to_new_page() thinks this is an error code and assigns
  newpage->mapping to NULL.  Newly migrated page lose connectivity with
  balloon an all ability for further migration.

* lru_lock erroneously required in isolate_migratepages_range() for
  isolation ballooned page.  This function releases lru_lock periodically,
  this makes migration mostly impossible for some pages.

* balloon_page_dequeue have a tight race with balloon_page_isolate:
  balloon_page_isolate could be executed in parallel with dequeue between
  picking page from list and locking page_lock.  Race is rare because they
  use trylock_page() for locking.

This patch fixes all of them.

Instead of fake mapping with special flag this patch uses special state of
page->_mapcount: PAGE_BALLOON_MAPCOUNT_VALUE = -256.  Buddy allocator uses
PAGE_BUDDY_MAPCOUNT_VALUE = -128 for similar purpose.  Storing mark
directly in struct page makes everything safer and easier.

PagePrivate is used to mark pages present in page list (i.e.  not
isolated, like PageLRU for normal pages).  It replaces special rules for
reference counter and makes balloon migration similar to migration of
normal pages.  This flag is protected by page_lock together with link to
the balloon device.

Signed-off-by: Konstantin Khlebnikov 
Reported-by: Sasha Levin 
Link: http://lkml.kernel.org/p/53E6CEAA.9020105@oracle.com
Cc: Rafael Aquini 
Cc: Andrey Ryabinin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

arm64,ia64,ppc,s390,sh,tile,um,x86,mm: remove default gate area

2014-08-08T22:57:27+00:00

The core mm code will provide a default gate area based on
FIXADDR_USER_START and FIXADDR_USER_END if
!defined(__HAVE_ARCH_GATE_AREA) && defined(AT_SYSINFO_EHDR).

This default is only useful for ia64.  arm64, ppc, s390, sh, tile, 64-bit
UML, and x86_32 have their own code just to disable it.  arm, 32-bit UML,
and x86_64 have gate areas, but they have their own implementations.

This gets rid of the default and moves the code into ia64.

This should save some code on architectures without a gate area: it's now
possible to inline the gate_area functions in the default case.

Signed-off-by: Andy Lutomirski 
Acked-by: Nathan Lynch 
Acked-by: H. Peter Anvin 
Acked-by: Benjamin Herrenschmidt  [in principle]
Acked-by: Richard Weinberger  [for um]
Acked-by: Will Deacon  [for arm64]
Cc: Catalin Marinas 
Cc: Will Deacon 
Cc: Tony Luck 
Cc: Fenghua Yu 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Martin Schwidefsky 
Cc: Heiko Carstens 
Cc: Chris Metcalf 
Cc: Jeff Dike 
Cc: Richard Weinberger 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: "H. Peter Anvin" 
Cc: Nathan Lynch 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'x86/vdso' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into next

2014-06-05T15:05:29+00:00

Pull x86 cdso updates from Peter Anvin:
 "Vdso cleanups and improvements largely from Andy Lutomirski.  This
  makes the vdso a lot less ''special''"

* 'x86/vdso' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/vdso, build: Make LE access macros clearer, host-safe
  x86/vdso, build: Fix cross-compilation from big-endian architectures
  x86/vdso, build: When vdso2c fails, unlink the output
  x86, vdso: Fix an OOPS accessing the HPET mapping w/o an HPET
  x86, mm: Replace arch_vma_name with vm_ops->name for vsyscalls
  x86, mm: Improve _install_special_mapping and fix x86 vdso naming
  mm, fs: Add vm_ops->name as an alternative to arch_vma_name
  x86, vdso: Fix an OOPS accessing the HPET mapping w/o an HPET
  x86, vdso: Remove vestiges of VDSO_PRELINK and some outdated comments
  x86, vdso: Move the vvar and hpet mappings next to the 64-bit vDSO
  x86, vdso: Move the 32-bit vdso special pages after the text
  x86, vdso: Reimplement vdso.so preparation in build-time C
  x86, vdso: Move syscall and sysenter setup into kernel/cpu/common.c
  x86, vdso: Clean up 32-bit vs 64-bit vdso params
  x86, mm: Ensure correct alignment of the fixmap

mm: introdule compound_head_by_tail()

2014-06-04T23:54:03+00:00

Currently, in put_compound_page(), we have

======
if (likely(!PageTail(page))) {                  <------  (1)
        if (put_page_testzero(page)) {
                 /*
                 ¦* By the time all refcounts have been released
                 ¦* split_huge_page cannot run anymore from under us.
                 ¦*/
                 if (PageHead(page))
                         __put_compound_page(page);
                 else
                         __put_single_page(page);
         }
         return;
}

/* __split_huge_page_refcount can run under us */
page_head = compound_head(page);        <------------ (2)
======

if at (1) ,  we fail the check, this means page is *likely* a tail page.

Then at (2), as compoud_head(page) is inlined, it is :

======
static inline struct page *compound_head(struct page *page)
{
          if (unlikely(PageTail(page))) {           <----------- (3)
              struct page *head = page->first_page;

                smp_rmb();
                if (likely(PageTail(page)))
                        return head;
        }
        return page;
}
======

here, the (3) unlikely in the case is a negative hint, because it is
*likely* a tail page.  So the check (3) in this case is not good, so I
introduce a helper for this case.

So this patch introduces compound_head_by_tail() which deals with a
possible tail page(though it could be spilt by a racy thread), and make
compound_head() a wrapper on it.

This patch has no functional change, and it reduces the object
size slightly:
   text    data     bss     dec     hex  filename
  11003    1328      16   12347    303b  mm/swap.o.orig
  10971    1328      16   12315    301b  mm/swap.o.patched

I've ran "perf top -e branch-miss" to observe branch-miss in this case.
As Michael points out, it's a slow path, so only very few times this case
happens.  But I grep'ed the code base, and found there still are some
other call sites could be benifited from this helper.  And given that it
only bloating up the source by only 5 lines, but with a reduced object
size.  I still believe this helper deserves to exsit.

Signed-off-by: Jianyu Zhan 
Cc: Kirill A. Shutemov 
Cc: Rik van Riel 
Cc: Jiang Liu 
Cc: Peter Zijlstra 
Cc: Johannes Weiner 
Cc: Mel Gorman 
Cc: Andrea Arcangeli 
Cc: Sasha Levin 
Cc: Wanpeng Li 
Cc: Hugh Dickins 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge remote-tracking branch 'origin/x86/espfix' into x86/vdso

2014-05-22T00:36:33+00:00

Merge x86/espfix into x86/vdso, due to changes in the vdso setup code
that otherwise cause conflicts.

Signed-off-by: H. Peter Anvin

x86, mm: Improve _install_special_mapping and fix x86 vdso naming

2014-05-20T18:38:42+00:00

Using arch_vma_name to give special mappings a name is awkward.  x86
currently implements it by comparing the start address of the vma to
the expected address of the vdso.  This requires tracking the start
address of special mappings and is probably buggy if a special vma
is split or moved.

Improve _install_special_mapping to just name the vma directly.  Use
it to give the x86 vvar area a name, which should make CRIU's life
easier.

As a side effect, the vvar area will show up in core dumps.  This
could be considered weird and is fixable.

[hpa: I say we accept this as-is but be prepared to deal with knocking
 out the vvars from core dumps if this becomes a problem.]

Cc: Cyrill Gorcunov 
Cc: Pavel Emelyanov 
Signed-off-by: Andy Lutomirski 
Link: http://lkml.kernel.org/r/276b39b6b645fb11e345457b503f17b83c2c6fd0.1400538962.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin

mm, fs: Add vm_ops->name as an alternative to arch_vma_name

2014-05-20T18:36:31+00:00

arch_vma_name sucks.  It's a silly hack, and it's annoying to
implement correctly.  In fact, AFAICS, even the straightforward x86
implementation is incorrect (I suspect that it breaks if the vdso
mapping is split or gets remapped).

This adds a new vm_ops->name operation that can replace it.  The
followup patches will remove all uses of arch_vma_name on x86,
fixing a couple of annoyances in the process.

Signed-off-by: Andy Lutomirski 
Link: http://lkml.kernel.org/r/2eee21791bb36a0a408c5c2bdb382a9e6a41ca4a.1400538962.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin

nick kvfree() from apparmor

2014-05-06T18:02:53+00:00

too many places open-code it

Signed-off-by: Al Viro