linux-stable.git/include/linux/hugetlb.h, branch v3.3.6

hugepages: fix use after free bug in "quota" handling

2012-05-12T16:32:21+00:00

commit 90481622d75715bfcb68501280a917dbfe516029 upstream.

hugetlbfs_{get,put}_quota() are badly named.  They don't interact with the
general quota handling code, and they don't much resemble its behaviour.
Rather than being about maintaining limits on on-disk block usage by
particular users, they are instead about maintaining limits on in-memory
page usage (including anonymous MAP_PRIVATE copied-on-write pages)
associated with a particular hugetlbfs filesystem instance.

Worse, they work by having callbacks to the hugetlbfs filesystem code from
the low-level page handling code, in particular from free_huge_page().
This is a layering violation of itself, but more importantly, if the
kernel does a get_user_pages() on hugepages (which can happen from KVM
amongst others), then the free_huge_page() can be delayed until after the
associated inode has already been freed.  If an unmount occurs at the
wrong time, even the hugetlbfs superblock where the "quota" limits are
stored may have been freed.

Andrew Barry proposed a patch to fix this by having hugepages, instead of
storing a pointer to their address_space and reaching the superblock from
there, had the hugepages store pointers directly to the superblock,
bumping the reference count as appropriate to avoid it being freed.
Andrew Morton rejected that version, however, on the grounds that it made
the existing layering violation worse.

This is a reworked version of Andrew's patch, which removes the extra, and
some of the existing, layering violation.  It works by introducing the
concept of a hugepage "subpool" at the lower hugepage mm layer - that is a
finite logical pool of hugepages to allocate from.  hugetlbfs now creates
a subpool for each filesystem instance with a page limit set, and a
pointer to the subpool gets added to each allocated hugepage, instead of
the address_space pointer used now.  The subpool has its own lifetime and
is only freed once all pages in it _and_ all other references to it (i.e.
superblocks) are gone.

subpools are optional - a NULL subpool pointer is taken by the code to
mean that no subpool limits are in effect.

Previous discussion of this bug found in:  "Fix refcounting in hugetlbfs
quota handling.". See:  https://lkml.org/lkml/2011/8/11/28 or
http://marc.info/?l=linux-mm&m=126928970510627&w=1

v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to
alloc_huge_page() - since it already takes the vma, it is not necessary.

Signed-off-by: Andrew Barry 
Signed-off-by: David Gibson 
Cc: Hugh Dickins 
Cc: Mel Gorman 
Cc: Minchan Kim 
Cc: Hillf Danton 
Cc: Paul Mackerras 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

hugetlb: remove dummy definitions of HPAGE_MASK and HPAGE_SIZE

2011-11-19T11:15:59+00:00

Dummy, non-zero definitions for HPAGE_MASK and HPAGE_SIZE were added in
51c6f666fceb ("mm: ZAP_BLOCK causes redundant work") to avoid a divide
by zero in generic kernel code.

That code has since been removed, but probably should never have been
added in the first place: we don't want HPAGE_SIZE to act like PAGE_SIZE
for code that is working with hugepages, for example, when the
dependency on CONFIG_HUGETLB_PAGE has not been fulfilled.

Because hugepage size can differ from architecture to architecture, each
is required to have their own definitions for both HPAGE_MASK and
HPAGE_SIZE.  This is always done in arch/*/include/asm/page.h.

So, just remove the dummy and dangerous definitions since they are no
longer needed and reveals the correct dependencies.  Tested on
architectures using the definitions with allyesconfig: x86 (even with
thp), hppa, mips, powerpc, s390, sh3, sh4, sparc, and sparc64, and with
defconfig on ia64.

Signed-off-by: David Rientjes 
Signed-off-by: Linus Torvalds

hugetlb: add phys addr to struct huge_bootmem_page

2011-07-26T03:57:07+00:00

This is needed on HIGHMEM systems - we don't always have a virtual
address so store the physical address and map it in as needed.

[akpm@linux-foundation.org: cleanup]
Signed-off-by: Becky Bruce 
Cc: Benjamin Herrenschmidt 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Fix build with !HUGETLBFS

2011-05-26T19:03:50+00:00

I stupidly broke the case of CONFIG_HUGETLBFS=n when doing the
conversion to vm_flags_t in commit ca16d140af91 ("mm: don't access
vm_flags as 'int'").  And my 'allyesconfig' build didn't find it, for
obvious reasons..

Include  in .  The problem could have
been avoided by just turning the hugetlb_file_setup() error wrapper into
a macro, but mm_types.h is a reasonable include in this file.

Reported-by: Richard -rw- Weinberger 
Signed-off-by: Linus Torvalds

mm: don't access vm_flags as 'int'

2011-05-26T16:20:31+00:00

The type of vma->vm_flags is 'unsigned long'. Neither 'int' nor
'unsigned int'. This patch fixes such misuse.

Signed-off-by: KOSAKI Motohiro 
[ Changed to use a typedef - we'll extend it to cover more cases
  later, since there has been discussion about making it a 64-bit
  type..                      - Linus ]
Signed-off-by: Linus Torvalds

Encode huge page size for VM_FAULT_HWPOISON errors

2010-10-08T07:32:46+00:00

This fixes a problem introduced with the hugetlb hwpoison handling

The user space SIGBUS signalling wants to know the size of the hugepage
that caused a HWPOISON fault.

Unfortunately the architecture page fault handlers do not have easy
access to the struct page.

Pass the information out in the fault error code instead.

I added a separate VM_FAULT_HWPOISON_LARGE bit for this case and encode
the hpage index in some free upper bits of the fault code. The small
page hwpoison keeps stays with the VM_FAULT_HWPOISON name to minimize
changes.

Also add code to hugetlb.h to convert that index into a page shift.

Will be used in a further patch.

Cc: Naoya Horiguchi 
Cc: fengguang.wu@intel.com
Signed-off-by: Andi Kleen

HWPOISON, hugetlb: add free check to dequeue_hwpoison_huge_page()

2010-10-08T07:32:45+00:00

This check is necessary to avoid race between dequeue and allocation,
which can cause a free hugepage to be dequeued twice and get kernel unstable.

Signed-off-by: Naoya Horiguchi 
Signed-off-by: Wu Fengguang 
Acked-by: Mel Gorman 
Reviewed-by: Christoph Lameter 
Signed-off-by: Andi Kleen

hugetlb: redefine hugepage copy functions

2010-10-08T07:32:44+00:00

This patch modifies hugepage copy functions to have only destination
and source hugepages as arguments for later use.
The old ones are renamed from copy_{gigantic,huge}_page() to
copy_user_{gigantic,huge}_page().
This naming convention is consistent with that between copy_highpage()
and copy_user_highpage().

ChangeLog since v4:
- add blank line between local declaration and code
- remove unnecessary might_sleep()

ChangeLog since v2:
- change copy_huge_page() from macro to inline dummy function
  to avoid compile warning when !CONFIG_HUGETLB_PAGE.

Signed-off-by: Naoya Horiguchi 
Acked-by: Mel Gorman 
Reviewed-by: Christoph Lameter 
Signed-off-by: Andi Kleen

hugetlb: add allocate function for hugepage migration

2010-10-08T07:32:44+00:00

We can't use existing hugepage allocation functions to allocate hugepage
for page migration, because page migration can happen asynchronously with
the running processes and page migration users should call the allocation
function with physical addresses (not virtual addresses) as arguments.

ChangeLog since v3:
- unify alloc_buddy_huge_page() and alloc_buddy_huge_page_node()

ChangeLog since v2:
- remove unnecessary get/put_mems_allowed() (thanks to David Rientjes)

ChangeLog since v1:
- add comment on top of alloc_huge_page_no_vma()

Signed-off-by: Naoya Horiguchi 
Acked-by: Mel Gorman 
Signed-off-by: Jun'ichi Nomura 
Reviewed-by: Christoph Lameter 
Signed-off-by: Andi Kleen

HWPOISON, hugetlb: isolate corrupted hugepage

2010-08-11T07:22:46+00:00

If error hugepage is not in-use, we can fully recovery from error
by dequeuing it from freelist, so return RECOVERY.
Otherwise whether or not we can recovery depends on user processes,
so return DELAYED.

Dependency:
  "HWPOISON, hugetlb: enable error handling path for hugepage"

Signed-off-by: Naoya Horiguchi 
Cc: Andrew Morton 
Acked-by: Fengguang Wu 
Signed-off-by: Andi Kleen