Commit graph

59 commits

Author SHA1 Message Date
Catalin Marinas
b370d29ea7 kmemleak: Disable early logging when kmemleak is off by default
Commit b6693005 (kmemleak: When the early log buffer is exceeded, report
the actual number) deferred the disabling of the early logging to
kmemleak_init(). However, when CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y, the
early logging was no longer disabled causing __init kmemleak functions
to be called even after the kernel freed the init memory. This patch
disables the early logging during kmemleak_init() if kmemleak is left
disabled.

Reported-by: Dirk Gouders <gouders@et.bocholt.fh-gelsenkirchen.de>
Tested-by: Dirk Gouders <gouders@et.bocholt.fh-gelsenkirchen.de>
Tested-by: Josh Boyer <jwboyer@gmail.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2012-01-20 16:57:05 +00:00
Tiejun Chen
b469d4329c kmemleak: Only scan non-zero-size areas
Kmemleak should only track valid scan areas with a non-zero size.
Otherwise, such area may reside just at the end of an object and
kmemleak would report "Adding scan area to unknown object".

Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2012-01-20 16:54:35 +00:00
Laura Abbott
029aeff5db kmemleak: Add support for memory hotplug
Ensure that memory hotplug can co-exist with kmemleak
by taking the hotplug lock before scanning the memory
banks.

Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2011-12-02 16:12:42 +00:00
Catalin Marinas
f528f0b8e5 kmemleak: Handle percpu memory allocation
This patch adds kmemleak callbacks from the percpu allocator, reducing a
number of false positives caused by kmemleak not scanning such memory
blocks. The percpu chunks are never reported as leaks because of current
kmemleak limitations with the __percpu pointer not pointing directly to
the actual chunks.

Reported-by: Huajun Li <huajun.li.lee@gmail.com>
Acked-by: Christoph Lameter <cl@gentwo.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2011-12-02 16:12:42 +00:00
Catalin Marinas
74341703ed kmemleak: Report previously found leaks even after an error
If an error fatal to kmemleak (like memory allocation failure) happens,
kmemleak disables itself but it also removes the access to any
previously found memory leaks. This patch allows read-only access to the
kmemleak debugfs interface but disables any other action.

Reported-by: Nick Bowler <nbowler@elliptictech.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2011-12-02 16:12:42 +00:00
Catalin Marinas
b66930052a kmemleak: When the early log buffer is exceeded, report the actual number
Just telling that the early log buffer has been exceeded doesn't mean
much. This patch moves the error printing to the kmemleak_init()
function and displays the actual calls to the kmemleak API during early
logging.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2011-12-02 16:12:42 +00:00
Catalin Marinas
5f79020cb9 kmemleak: Show where early_log issues come from
Based on initial patch by Steven Rostedt.

Early kmemleak warnings did not show where the actual kmemleak API had
been called from but rather just a backtrace to the kmemleak_init()
function. By having all early kmemleak logs record the stack_trace, we
can have kmemleak_init() write exactly where the problem occurred. This
patch adds the setting of the kmemleak_warning variable every time a
kmemleak warning is issued. The kmemleak_init() function checks this
variable during early log replaying and prints the log trace if there
was any warning.

Reported-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@google.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
2011-12-02 16:12:41 +00:00
Paul Gortmaker
b95f1b31b7 mm: Map most files to use export.h instead of module.h
The files changed within are only using the EXPORT_SYMBOL
macro variants.  They are not using core modular infrastructure
and hence don't need module.h but only the export.h header.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2011-10-31 09:20:12 -04:00
Arun Sharma
60063497a9 atomic: use <linux/atomic.h>
This allows us to move duplicated code in <asm/atomic.h>
(atomic_inc_not_zero() for now) to <linux/atomic.h>

Signed-off-by: Arun Sharma <asharma@fb.com>
Reviewed-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-26 16:49:47 -07:00
Catalin Marinas
52c3ce4ec5 kmemleak: Do not return a pointer to an object that kmemleak did not get
The kmemleak_seq_next() function tries to get an object (and increment
its use count) before returning it. If it could not get the last object
during list traversal (because it may have been freed), the function
should return NULL rather than a pointer to such object that it did not
get.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Acked-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Cc: <stable@kernel.org>
2011-05-19 17:35:28 +01:00
Lucas De Marchi
25985edced Fix common misspellings
Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
2011-03-31 11:26:23 -03:00
Catalin Marinas
6ae4bd1f0b kmemleak: Allow kmemleak metadata allocations to fail
This patch adds __GFP_NORETRY and __GFP_NOMEMALLOC flags to the kmemleak
metadata allocations so that it has a smaller effect on the users of the
kernel slab allocator. Since kmemleak allocations can now fail more
often, this patch also reduces the verbosity by passing __GFP_NOWARN and
not dumping the stack trace when a kmemleak allocation fails.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Toralf Förster <toralf.foerster@gmx.de>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Ted Ts'o <tytso@mit.edu>
2011-01-27 18:32:06 +00:00
Holger Hans Peter Freyther
145b64b958 kmemleak: Fix typo in the comment
Fix typo in comment.

Signed-off-by: Holger Hans Peter Freyther <zecke@selfish.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2010-08-08 21:57:23 +01:00
Catalin Marinas
a2b6bf63cb kmemleak: Add DocBook style comments to kmemleak.c
The description and parameters of the kmemleak API weren't obvious. This
patch adds comments clarifying the API usage.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
2010-07-19 11:54:17 +01:00
Jason Baron
ab0155a22a kmemleak: Introduce a default off mode for kmemleak
Introduce a new DEBUG_KMEMLEAK_DEFAULT_OFF config parameter that allows
kmemleak to be disabled by default, but enabled on the command line
via: kmemleak=on. Although a reboot is required to turn it on, its still
useful to not require a re-compile.

Signed-off-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
2010-07-19 11:54:17 +01:00
Catalin Marinas
a7686a45c0 kmemleak: Show more information for objects found by alias
There may be situations when an object is freed using a pointer inside
the memory block. Kmemleak should show more information to help with
debugging.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
2010-07-19 11:54:16 +01:00
Tejun Heo
5a0e3ad6af include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-30 22:02:32 +09:00
Linus Torvalds
dcc7cd0112 Merge branch 'kmemleak' of git://linux-arm.org/linux-2.6
* 'kmemleak' of git://linux-arm.org/linux-2.6:
  kmemleak: fix kconfig for crc32 build error
  kmemleak: Reduce the false positives by checking for modified objects
  kmemleak: Show the age of an unreferenced object
  kmemleak: Release the object lock before calling put_object()
  kmemleak: Scan the _ftrace_events section in modules
  kmemleak: Simplify the kmemleak_scan_area() function prototype
  kmemleak: Do not use off-slab management with SLAB_NOLEAKTRACE
2009-12-17 16:00:19 -08:00
Uwe Kleine-Knig
21ae2956ce tree-wide: fix typos "aquire" -> "acquire", "cumsumed" -> "consumed"
This patch was generated by

	git grep -E -i -l '[Aa]quire' | xargs -r perl -p -i -e 's/([Aa])quire/$1cquire/'

and the cumsumed was found by checking the diff for aquire.

Signed-off-by: Uwe Kleine-Knig <u.kleine-koenig@pengutronix.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2009-11-09 09:40:57 +01:00
Catalin Marinas
04609ccc40 kmemleak: Reduce the false positives by checking for modified objects
If an object was modified since it was previously suspected as leak, do
not report it. The modification check is done by calculating the
checksum (CRC32) of such object.

Several false positives are caused by objects being removed from linked
lists (e.g. allocation pools) and temporarily breaking the reference
chain since kmemleak runs concurrently with such list mutation
primitives.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-10-28 17:07:54 +00:00
Catalin Marinas
fefdd336b2 kmemleak: Show the age of an unreferenced object
The jiffies shown for unreferenced objects isn't always meaningful to
people debugging kernel memory leaks. This patch adds the age as well to
the displayed information.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-10-28 17:07:54 +00:00
Catalin Marinas
0587da40be kmemleak: Release the object lock before calling put_object()
The put_object() function may free the object if the use_count
dropped to 0. There shouldn't be further accesses to such object unless
it is known that the use_count is non-zero.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-10-28 17:07:54 +00:00
Catalin Marinas
c017b4be3e kmemleak: Simplify the kmemleak_scan_area() function prototype
This function was taking non-necessary arguments which can be determined
by kmemleak. The patch also modifies the calling sites.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
2009-10-28 15:11:00 +00:00
Catalin Marinas
0d5d1aadc8 kmemleak: Check for NULL pointer returned by create_object()
This patch adds NULL pointer checking in the early_alloc() function.

Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-10-09 13:28:47 -07:00
Tetsuo Handa
c1bcd6b327 kmemleak: Use GFP_ATOMIC for early_alloc().
We can't use GFP_KERNEL inside rcu_read_lock().

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-10-09 13:28:47 -07:00
Catalin Marinas
addd72c1a9 kmemleak: Improve the "Early log buffer exceeded" error message
Based on a suggestion from Jaswinder, clarify what the user would need
to do to avoid this error message from kmemleak.

Reported-by: Jaswinder Singh Rajput <jaswinder@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-09-11 10:42:09 +01:00
Luis R. Rodriguez
7eb0d5e5be kmemleak: fix sparse warning for static declarations
This fixes these sparse warnings:

mm/kmemleak.c:1179:6: warning: symbol 'start_scan_thread' was not declared. Should it be static?
mm/kmemleak.c:1194:6: warning: symbol 'stop_scan_thread' was not declared. Should it be static?

Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-09-08 17:34:07 +01:00
Luis R. Rodriguez
0580a1819c kmemleak: fix sparse warning over overshadowed flags
A secondary irq_save is not required as a locking before it was
already disabling irqs.

This fixes this sparse warning:
mm/kmemleak.c:512:31: warning: symbol 'flags' shadows an earlier one
mm/kmemleak.c:448:23: originally declared here

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-09-08 17:34:06 +01:00
Luis R. Rodriguez
a1084c8779 kmemleak: move common painting code together
When painting grey or black we do the same thing, bring
this together into a helper and identify coloring grey or
black explicitly with defines. This makes this a little
easier to read.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-09-08 17:22:20 +01:00
Luis R. Rodriguez
30b3710105 kmemleak: add clear command support
In an ideal world your kmemleak output will be small, when its
not (usually during initial bootup) you can use the clear command
to ingore previously reported and unreferenced kmemleak objects. We
do this by painting all currently reported unreferenced objects grey.
We paint them grey instead of black to allow future scans on the same
objects as such objects could still potentially reference newly
allocated objects in the future.

To test a critical section on demand with a clean
/sys/kernel/debug/kmemleak you can do:

echo clear > /sys/kernel/debug/kmemleak
        test your kernel or modules
echo scan > /sys/kernel/debug/kmemleak

Then as usual to get your report with:

cat /sys/kernel/debug/kmemleak

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-09-08 16:36:08 +01:00
Luis R. Rodriguez
4a558dd6f9 kmemleak: use bool for true/false questions
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-09-08 16:34:50 +01:00
Catalin Marinas
179a8100e1 kmemleak: Do no create the clean-up thread during kmemleak_disable()
The kmemleak_disable() function could be called from various contexts
including IRQ. It creates a clean-up thread but the kthread_create()
function has restrictions on which contexts it can be called from,
mainly because of the kthread_create_lock. The patch changes the
kmemleak clean-up thread to a workqueue.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Eric Paris <eparis@redhat.com>
2009-09-08 16:31:15 +01:00
Catalin Marinas
43ed5d6ee0 kmemleak: Scan all thread stacks
This patch changes the for_each_process() loop with the
do_each_thread()/while_each_thread() pair.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-09-04 16:05:55 +01:00
Pekka Enberg
8e019366ba kmemleak: Don't scan uninitialized memory when kmemcheck is enabled
Ingo Molnar reported the following kmemcheck warning when running both
kmemleak and kmemcheck enabled:

  PM: Adding info for No Bus:vcsa7
  WARNING: kmemcheck: Caught 32-bit read from uninitialized memory
  (f6f6e1a4)
  d873f9f600000000c42ae4c1005c87f70000000070665f666978656400000000
   i i i i u u u u i i i i i i i i i i i i i i i i i i i i i u u u
           ^

  Pid: 3091, comm: kmemleak Not tainted (2.6.31-rc7-tip #1303) P4DC6
  EIP: 0060:[<c110301f>] EFLAGS: 00010006 CPU: 0
  EIP is at scan_block+0x3f/0xe0
  EAX: f40bd700 EBX: f40bd780 ECX: f16b46c0 EDX: 00000001
  ESI: f6f6e1a4 EDI: 00000000 EBP: f10f3f4c ESP: c2605fcc
   DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
  CR0: 8005003b CR2: e89a4844 CR3: 30ff1000 CR4: 000006f0
  DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
  DR6: ffff4ff0 DR7: 00000400
   [<c110313c>] scan_object+0x7c/0xf0
   [<c1103389>] kmemleak_scan+0x1d9/0x400
   [<c1103a3c>] kmemleak_scan_thread+0x4c/0xb0
   [<c10819d4>] kthread+0x74/0x80
   [<c10257db>] kernel_thread_helper+0x7/0x3c
   [<ffffffff>] 0xffffffff
  kmemleak: 515 new suspected memory leaks (see
  /sys/kernel/debug/kmemleak)
  kmemleak: 42 new suspected memory leaks (see /sys/kernel/debug/kmemleak)

The problem here is that kmemleak will scan partially initialized
objects that makes kmemcheck complain. Fix that up by skipping
uninitialized memory regions when kmemcheck is enabled.

Reported-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
2009-09-04 16:05:55 +01:00
Sergey Senozhatsky
0494e08281 kmemleak: Printing of the objects hex dump
Introducing printing of the objects hex dump to the seq file.
The number of lines to be printed is limited to HEX_MAX_LINES
to prevent seq file spamming. The actual number of printed
bytes is less than or equal to (HEX_MAX_LINES * HEX_ROW_SIZE).

(slight adjustments by Catalin Marinas)

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@mail.by>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-08-27 14:29:18 +01:00
Catalin Marinas
fd6789675e kmemleak: Save the stack trace for early allocations
Before slab is initialised, kmemleak save the allocations in an early
log buffer. They are later recorded as normal memory allocations. This
patch adds the stack trace saving to the early log buffer, otherwise the
information shown for such objects only refers to the kmemleak_init()
function.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-08-27 14:29:17 +01:00
Catalin Marinas
a6186d89c9 kmemleak: Mark the early log buffer as __initdata
This buffer isn't needed after kmemleak was initialised so it can be
freed together with the .init.data section. This patch also marks
functions conditionally accessing the early log variables with __ref.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-08-27 14:29:16 +01:00
Catalin Marinas
189d84ed54 kmemleak: Dump object information on request
By writing dump=<addr> to the kmemleak file, kmemleak will look up an
object with that address and dump the information it has about it to
syslog. This is useful in debugging memory leaks.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-08-27 14:29:15 +01:00
Catalin Marinas
af98603dad kmemleak: Allow rescheduling during an object scanning
If the object size is bigger than a predefined value (4K in this case),
release the object lock during scanning and call cond_resched().
Re-acquire the lock after rescheduling and test whether the object is
still valid.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-08-27 14:29:12 +01:00
Catalin Marinas
f5886c7f96 kmemleak: Protect the seq start/next/stop sequence by rcu_read_lock()
Objects passed to kmemleak_seq_next() have an incremented reference
count (hence not freed) but they may point via object_list.next to
other freed objects. To avoid this, the whole start/next/stop sequence
must be protected by rcu_read_lock().

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-07-29 12:34:58 -07:00
Catalin Marinas
53238a60dd kmemleak: Allow partial freeing of memory blocks
Functions like free_bootmem() are allowed to free only part of a memory
block. This patch adds support for this via the kmemleak_free_part()
callback which removes the original object and creates one or two
additional objects as a result of the memory block split.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
2009-07-08 14:25:14 +01:00
Catalin Marinas
2587362eaf kmemleak: Scan objects allocated during a scanning episode
Many of the false positives in kmemleak happen on busy systems where
objects are allocated during a kmemleak scanning episode. These objects
aren't scanned by default until the next memory scan. When such object
is added, for example, at the head of a list, it is possible that all
the other objects in the list become unreferenced until the next scan.

This patch adds checking for newly allocated objects at the end of the
scan and repeats the scanning on these objects. If Linux allocates
new objects at a higher rate than their scanning, it stops after a
predefined number of passes.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-07-08 14:25:13 +01:00
Catalin Marinas
b87324d082 kmemleak: Do not acquire scan_mutex in kmemleak_open()
Initially, the scan_mutex was acquired in kmemleak_open() and released
in kmemleak_release() (corresponding to /sys/kernel/debug/kmemleak
operations). This was causing some lockdep reports when the file was
closed from a different task than the one opening it. This patch moves
the scan_mutex acquiring in kmemleak_write() or kmemleak_seq_start()
with releasing in kmemleak_seq_stop().

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-07-08 14:25:13 +01:00
Catalin Marinas
288c857d66 kmemleak: Remove the reported leaks number limitation
Since the leaks are no longer printed to the syslog, there is no point
in keeping this limitation. All the suspected leaks are shown on
/sys/kernel/debug/kmemleak file.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-07-08 14:25:12 +01:00
Catalin Marinas
4b8a96744c kmemleak: Add more cond_resched() calls in the scanning thread
Following recent fix to no longer reschedule in the scan_block()
function, the system may become unresponsive with !PREEMPT. This patch
re-adds the cond_resched() call to scan_block() but conditioned by the
allow_resched parameter.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ingo Molnar <mingo@elte.hu>
2009-07-07 10:32:56 +01:00
Catalin Marinas
bf2a76b317 kmemleak: Renice the scanning thread to +10
This is a long-running thread but not high-priority. So it makes sense
to renice it to +10.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-07-07 10:32:55 +01:00
Ingo Molnar
57d81f6f39 kmemleak: Fix scheduling-while-atomic bug
One of the kmemleak changes caused the following
scheduling-while-holding-the-tasklist-lock regression on x86:

BUG: sleeping function called from invalid context at mm/kmemleak.c:795
in_atomic(): 1, irqs_disabled(): 0, pid: 1737, name: kmemleak
2 locks held by kmemleak/1737:
 #0:  (scan_mutex){......}, at: [<c10c4376>] kmemleak_scan_thread+0x45/0x86
 #1:  (tasklist_lock){......}, at: [<c10c3bb4>] kmemleak_scan+0x1a9/0x39c
Pid: 1737, comm: kmemleak Not tainted 2.6.31-rc1-tip #59266
Call Trace:
 [<c105ac0f>] ? __debug_show_held_locks+0x1e/0x20
 [<c102e490>] __might_sleep+0x10a/0x111
 [<c10c38d5>] scan_yield+0x17/0x3b
 [<c10c3970>] scan_block+0x39/0xd4
 [<c10c3bc6>] kmemleak_scan+0x1bb/0x39c
 [<c10c4331>] ? kmemleak_scan_thread+0x0/0x86
 [<c10c437b>] kmemleak_scan_thread+0x4a/0x86
 [<c104d73e>] kthread+0x6e/0x73
 [<c104d6d0>] ? kthread+0x0/0x73
 [<c100959f>] kernel_thread_helper+0x7/0x10
kmemleak: 834 new suspected memory leaks (see /sys/kernel/debug/kmemleak)

The bit causing it is highly dubious:

static void scan_yield(void)
{
        might_sleep();

        if (time_is_before_eq_jiffies(next_scan_yield)) {
                schedule();
                next_scan_yield = jiffies + jiffies_scan_yield;
        }
}

It called deep inside the codepath and in a conditional way,
and that is what crapped up when one of the new scan_block()
uses grew a tasklist_lock dependency.

This minimal patch removes that yielding stuff and adds the
proper cond_resched().

The background scanning thread could probably also be reniced
to +10.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-07-01 10:26:23 -07:00
Catalin Marinas
b6e687221e kmemleak: Do not warn if an unknown object is freed
vmap'ed memory blocks are not tracked by kmemleak (yet) but they may be
released with vfree() which is tracked. The corresponding kmemleak
warning is only enabled in debug mode. Future patch will add support for
ioremap and vmap.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-06-29 17:14:14 +01:00
Catalin Marinas
17bb9e0d90 kmemleak: Do not report new leaked objects if the scanning was stopped
If the scanning was stopped with a signal, it is possible that some
objects are left with a white colour (potential leaks) and reported. Add
a check to avoid reporting such objects.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-06-29 17:14:13 +01:00
Catalin Marinas
acf4968ec9 kmemleak: Slightly change the policy on newly allocated objects
Newly allocated objects are more likely to be reported as false
positives. Kmemleak ignores the reporting of objects younger than 5
seconds. However, this age was calculated after the memory scanning
completed which usually takes longer than 5 seconds. This patch
make the minimum object age calculation in relation to the start of the
memory scanning.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-06-26 17:38:29 +01:00