Cc: Catalin Marinas <catalin.mari...@arm.com>
Signed-off-by: Jonathan Corbet <cor...@lwn.net>
---
.../{kmemleak.txt => dev-tools/kmemleak.rst} | 93 ++++++++++++----------
Documentation/dev-tools/tools.rst | 1 +
MAINTAINERS | 2 +-
3 files changed, 52 insertions(+), 44 deletions(-)
rename Documentation/{kmemleak.txt => dev-tools/kmemleak.rst} (73%)
diff --git a/Documentation/kmemleak.txt b/Documentation/dev-tools/kmemleak.rst
similarity index 73%
rename from Documentation/kmemleak.txt
rename to Documentation/dev-tools/kmemleak.rst
index 18e24ab..1788722 100644
--- a/Documentation/kmemleak.txt
+++ b/Documentation/dev-tools/kmemleak.rst
@@ -1,15 +1,12 @@
Kernel Memory Leak Detector
===========================
-Introduction
-------------
-
Kmemleak provides a way of detecting possible kernel memory leaks in a
way similar to a tracing garbage collector
(https://en.wikipedia.org/wiki/Garbage_collection_%28computer_science%29#Tracing_garbage_collectors),
with the difference that the orphan objects are not freed but only
reported via /sys/kernel/debug/kmemleak. A similar method is used by the
-Valgrind tool (memcheck --leak-check) to detect the memory leaks in
+Valgrind tool (``memcheck --leak-check``) to detect the memory leaks in
user-space applications.
Kmemleak is supported on x86, arm, powerpc, sparc, sh, microblaze, ppc, mips,
s390, metag and tile.
@@ -19,20 +16,20 @@ Usage
CONFIG_DEBUG_KMEMLEAK in "Kernel hacking" has to be enabled. A kernel
thread scans the memory every 10 minutes (by default) and prints the
number of new unreferenced objects found. To display the details of all
-the possible memory leaks:
+the possible memory leaks::
# mount -t debugfs nodev /sys/kernel/debug/
# cat /sys/kernel/debug/kmemleak
-To trigger an intermediate memory scan:
+To trigger an intermediate memory scan::
# echo scan > /sys/kernel/debug/kmemleak
-To clear the list of all current possible memory leaks:
+To clear the list of all current possible memory leaks::
# echo clear > /sys/kernel/debug/kmemleak
-New leaks will then come up upon reading /sys/kernel/debug/kmemleak
+New leaks will then come up upon reading ``/sys/kernel/debug/kmemleak``
again.
Note that the orphan objects are listed in the order they were allocated
@@ -40,22 +37,31 @@ and one object at the beginning of the list may cause other
subsequent
objects to be reported as orphan.
Memory scanning parameters can be modified at run-time by writing to the
-/sys/kernel/debug/kmemleak file. The following parameters are supported:
-
- off - disable kmemleak (irreversible)
- stack=on - enable the task stacks scanning (default)
- stack=off - disable the tasks stacks scanning
- scan=on - start the automatic memory scanning thread (default)
- scan=off - stop the automatic memory scanning thread
- scan=<secs> - set the automatic memory scanning period in seconds
- (default 600, 0 to stop the automatic scanning)
- scan - trigger a memory scan
- clear - clear list of current memory leak suspects, done by
- marking all current reported unreferenced objects grey,
- or free all kmemleak objects if kmemleak has been disabled.
- dump=<addr> - dump information about the object found at <addr>
-
-Kmemleak can also be disabled at boot-time by passing "kmemleak=off" on
+``/sys/kernel/debug/kmemleak`` file. The following parameters are supported:
+
+- off
+ disable kmemleak (irreversible)
+- stack=on
+ enable the task stacks scanning (default)
+- stack=off
+ disable the tasks stacks scanning
+- scan=on
+ start the automatic memory scanning thread (default)
+- scan=off
+ stop the automatic memory scanning thread
+- scan=<secs>
+ set the automatic memory scanning period in seconds
+ (default 600, 0 to stop the automatic scanning)
+- scan
+ trigger a memory scan
+- clear
+ clear list of current memory leak suspects, done by
+ marking all current reported unreferenced objects grey,
+ or free all kmemleak objects if kmemleak has been disabled.
+- dump=<addr>
+ dump information about the object found at <addr>
+
+Kmemleak can also be disabled at boot-time by passing ``kmemleak=off`` on
the kernel command line.
Memory may be allocated or freed before kmemleak is initialised and
@@ -63,13 +69,14 @@ these actions are stored in an early log buffer. The size
of this buffer
is configured via the CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE option.
If CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF are enabled, the kmemleak is
-disabled by default. Passing "kmemleak=on" on the kernel command
+disabled by default. Passing ``kmemleak=on`` on the kernel command
line enables the function.
Basic Algorithm
---------------
-The memory allocations via kmalloc, vmalloc, kmem_cache_alloc and
+The memory allocations via :c:func:`kmalloc`, :c:func:`vmalloc`,
+:c:func:`kmem_cache_alloc` and
friends are traced and the pointers, together with additional
information like size and stack trace, are stored in a rbtree.
The corresponding freeing function calls are tracked and the pointers
@@ -113,13 +120,13 @@ when doing development. To work around these situations
you can use the
you can find new unreferenced objects; this should help with testing
specific sections of code.
-To test a critical section on demand with a clean kmemleak do:
+To test a critical section on demand with a clean kmemleak 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:
+Then as usual to get your report with::
# cat /sys/kernel/debug/kmemleak
@@ -131,7 +138,7 @@ disabled by the user or due to an fatal error, internal
kmemleak objects
won't be freed when kmemleak is disabled, and those objects may occupy
a large part of physical memory.
-In this situation, you may reclaim memory with:
+In this situation, you may reclaim memory with::
# echo clear > /sys/kernel/debug/kmemleak
@@ -140,20 +147,20 @@ Kmemleak API
See the include/linux/kmemleak.h header for the functions prototype.
-kmemleak_init - initialize kmemleak
-kmemleak_alloc - notify of a memory block allocation
-kmemleak_alloc_percpu - notify of a percpu memory block allocation
-kmemleak_free - notify of a memory block freeing
-kmemleak_free_part - notify of a partial memory block freeing
-kmemleak_free_percpu - notify of a percpu memory block freeing
-kmemleak_update_trace - update object allocation stack trace
-kmemleak_not_leak - mark an object as not a leak
-kmemleak_ignore - do not scan or report an object as leak
-kmemleak_scan_area - add scan areas inside a memory block
-kmemleak_no_scan - do not scan a memory block
-kmemleak_erase - erase an old value in a pointer variable
-kmemleak_alloc_recursive - as kmemleak_alloc but checks the recursiveness
-kmemleak_free_recursive - as kmemleak_free but checks the recursiveness
+- ``kmemleak_init`` - initialize kmemleak
+- ``kmemleak_alloc`` - notify of a memory block allocation
+- ``kmemleak_alloc_percpu`` - notify of a percpu memory block allocation
+- ``kmemleak_free`` - notify of a memory block freeing
+- ``kmemleak_free_part`` - notify of a partial memory block freeing
+- ``kmemleak_free_percpu`` - notify of a percpu memory block freeing
+- ``kmemleak_update_trace`` - update object allocation stack trace
+- ``kmemleak_not_leak`` - mark an object as not a leak
+- ``kmemleak_ignore`` - do not scan or report an object as leak
+- ``kmemleak_scan_area`` - add scan areas inside a memory block
+- ``kmemleak_no_scan`` - do not scan a memory block
+- ``kmemleak_erase`` - erase an old value in a pointer variable
+- ``kmemleak_alloc_recursive`` - as kmemleak_alloc but checks the recursiveness
+- ``kmemleak_free_recursive`` - as kmemleak_free but checks the recursiveness
Dealing with false positives/negatives
--------------------------------------
diff --git a/Documentation/dev-tools/tools.rst
b/Documentation/dev-tools/tools.rst
index 2d11297..3b6382a 100644
--- a/Documentation/dev-tools/tools.rst
+++ b/Documentation/dev-tools/tools.rst
@@ -20,3 +20,4 @@ whole; patches welcome!
gcov
kasan
ubsan
+ kmemleak
diff --git a/MAINTAINERS b/MAINTAINERS
index 2ffd7ed..b235e0d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6812,7 +6812,7 @@ F: mm/kmemcheck.c
KMEMLEAK
M: Catalin Marinas <catalin.mari...@arm.com>
S: Maintained
-F: Documentation/kmemleak.txt
+F: Documentation/dev-tools/kmemleak.rst
F: include/linux/kmemleak.h
F: mm/kmemleak.c
F: mm/kmemleak-test.c
--
2.9.2
