linux-stable.git/drivers/block/aoe, branch linux-3.13.y

mm: close PageTail race

2014-04-03T19:02:37+00:00

commit 668f9abbd4334e6c29fa8acd71635c4f9101caa7 upstream.

Commit bf6bddf1924e ("mm: introduce compaction and migration for
ballooned pages") introduces page_count(page) into memory compaction
which dereferences page->first_page if PageTail(page).

This results in a very rare NULL pointer dereference on the
aforementioned page_count(page).  Indeed, anything that does
compound_head(), including page_count() is susceptible to racing with
prep_compound_page() and seeing a NULL or dangling page->first_page
pointer.

This patch uses Andrea's implementation of compound_trans_head() that
deals with such a race and makes it the default compound_head()
implementation.  This includes a read memory barrier that ensures that
if PageTail(head) is true that we return a head page that is neither
NULL nor dangling.  The patch then adds a store memory barrier to
prep_compound_page() to ensure page->first_page is set.

This is the safest way to ensure we see the head page that we are
expecting, PageTail(page) is already in the unlikely() path and the
memory barriers are unfortunately required.

Hugetlbfs is the exception, we don't enforce a store memory barrier
during init since no race is possible.

Signed-off-by: David Rientjes 
Cc: Holger Kiehl 
Cc: Christoph Lameter 
Cc: Rafael Aquini 
Cc: Vlastimil Babka 
Cc: Michal Hocko 
Cc: Mel Gorman 
Cc: Andrea Arcangeli 
Cc: Rik van Riel 
Cc: "Kirill A. Shutemov" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

aoe: do not BUG if memory pressure prevented debugfs file creation

2013-09-11T22:59:28+00:00

If the system has trouble allocating memory for the creation of the aoe
debugfs directory or of a file inside it, the debugfs member of an aoedev
can be NULL.

Do not treat a NULL debugfs pointer as a BUG on aoedev shutdown, avoiding
the user impact of an unecessary panic.

Signed-off-by: Ed Cashin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: suppress compiler warnings

2013-09-11T22:59:27+00:00

This patch fixes following compiler warnings:

  drivers/block/aoe/aoecmd.c: In function `aoecmd_ata_rw':
  drivers/block/aoe/aoecmd.c:383:17: warning: variable `t' set but not used [-Wunused-but-set-variable]
    struct aoetgt *t;
                   ^
  drivers/block/aoe/aoecmd.c: In function `resend':
  drivers/block/aoe/aoecmd.c:488:21: warning: variable `ah' set but not used [-Wunused-but-set-variable]
    struct aoe_atahdr *ah;
                       ^

Signed-off-by: Andy Shevchenko 
Cc: Ed Cashin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: remove custom implementation of kbasename()

2013-09-11T22:59:26+00:00

In the kernel we have a nice helper that may be used here. This patch
substitutes the custom implementation by the native function call.

Signed-off-by: Andy Shevchenko 
Cc: Ed Cashin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: update internal version number to 85

2013-09-11T22:59:26+00:00

Signed-off-by: Ed Cashin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: update copyright date

2013-09-11T22:59:25+00:00

Signed-off-by: Ed Cashin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: fill in per-AoE-target information for debugfs file

2013-09-11T22:59:25+00:00

This information is presented in a compact format that has evolved for
easy routine scanning by expert humans, mostly developers and support
technicians helping to troubleshoot or test AoE-based systems.

Signed-off-by: Ed Cashin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: provide file operations for debugfs files

2013-09-11T22:59:24+00:00

The place holder in the file contents is filled out in the following
patch.

Signed-off-by: Ed Cashin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: add AoE-target files to debugfs

2013-09-11T22:59:23+00:00

Signed-off-by: Ed Cashin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: create and destroy debugfs directory for aoe

2013-09-11T22:59:22+00:00

This series adds the debugging information that the coraid.com-distributed
aoe driver exports via sysfs, but instead of sysfs, it uses debugfs.

With these patches applied, even without AoE targets on the network, KEDR
reports new possible memory leaks, but these are from callers outside the
aoe driver that have used aoe_devnode to get the name of the character
devices through the aoe_class->devnode callback, and I believe they're
responsible for freeing that memory.

This patch:

Create and destroy the debugfs directory.

Signed-off-by: Ed Cashin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds