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kmemleak: add clear command support

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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>
This commit is contained in:
Luis R. Rodriguez 2009-09-04 17:44:51 -07:00 committed by Catalin Marinas
parent 4a558dd6f9
commit 30b3710105
2 changed files with 56 additions and 0 deletions
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30
Documentation/kmemleak.txt
View file

@ -27,6 +27,13 @@ To trigger an intermediate memory scan:
# echo scan > /sys/kernel/debug/kmemleak
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
again.
Note that the orphan objects are listed in the order they were allocated
and one object at the beginning of the list may cause other subsequent
objects to be reported as orphan.
@ -42,6 +49,8 @@ Memory scanning parameters can be modified at run-time by writing to the
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
dump=<addr> - dump information about the object found at <addr>
Kmemleak can also be disabled at boot-time by passing "kmemleak=off" on
@ -87,6 +96,27 @@ avoid this, kmemleak can also store the number of values pointing to an
address inside the block address range that need to be found so that the
block is not considered a leak. One example is __vmalloc().
Testing specific sections with kmemleak
---------------------------------------
Upon initial bootup your /sys/kernel/debug/kmemleak output page may be
quite extensive. This can also be the case if you have very buggy code
when doing development. To work around these situations you can use the
'clear' command to clear all reported unreferenced objects from the
/sys/kernel/debug/kmemleak output. By issuing a 'scan' after a 'clear'
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:
# 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
Kmemleak API
------------

26
mm/kmemleak.c
View file

@ -1420,6 +1420,28 @@ static int dump_str_object_info(const char *str)
return 0;
}
/*
* We use grey instead of black to ensure we can do future scans on the same
* objects. If we did not do future scans these black objects could
* potentially contain references to newly allocated objects in the future and
* we'd end up with false positives.
*/
static void kmemleak_clear(void)
{
struct kmemleak_object *object;
unsigned long flags;
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list) {
spin_lock_irqsave(&object->lock, flags);
if ((object->flags & OBJECT_REPORTED) &&
unreferenced_object(object))
object->min_count = 0;
spin_unlock_irqrestore(&object->lock, flags);
}
rcu_read_unlock();
}
/*
* File write operation to configure kmemleak at run-time. The following
* commands can be written to the /sys/kernel/debug/kmemleak file:
@ -1431,6 +1453,8 @@ static int dump_str_object_info(const char *str)
* scan=... - set the automatic memory scanning period in seconds (0 to
* disable it)
* scan - trigger a memory scan
* clear - mark all current reported unreferenced kmemleak objects as
* grey to ignore printing them
* dump=... - dump information about the object found at the given address
*/
static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
@ -1472,6 +1496,8 @@ static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
}
} else if (strncmp(buf, "scan", 4) == 0)
kmemleak_scan();
else if (strncmp(buf, "clear", 5) == 0)
kmemleak_clear();
else if (strncmp(buf, "dump=", 5) == 0)
ret = dump_str_object_info(buf + 5);
else