Subject: + kmemleak-allow-freeing-internal-objects-after-kmemleak-was-disabled.patch added to -mm tree
To: lizefan@xxxxxxxxxx,catalin.marinas@xxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Fri, 21 Mar 2014 14:30:11 -0700
The patch titled
Subject: kmemleak: allow freeing internal objects after kmemleak was disabled
has been added to the -mm tree. Its filename is
kmemleak-allow-freeing-internal-objects-after-kmemleak-was-disabled.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kmemleak-allow-freeing-internal-objects-after-kmemleak-was-disabled.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kmemleak-allow-freeing-internal-objects-after-kmemleak-was-disabled.patch
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------------------------------------------------------
From: Li Zefan <lizefan@xxxxxxxxxx>
Subject: kmemleak: allow freeing internal objects after kmemleak was disabled
Currently if kmemleak is disabled, the kmemleak objects can never be
freed, no matter if it's disabled by a user or due to fatal errors.
Those objects can be a big waste of memory.
OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME
1200264 1197433 99% 0.30K 46164 26 369312K kmemleak_object
With this patch, internal objects will be freed immediately if kmemleak is
disabled explicitly by a user. If it's disabled due to a kmemleak error,
The user will be informed, and then he/she can reclaim memory with:
# echo off > /sys/kernel/debug/kmemleak
Signed-off-by: Li Zefan <lizefan@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/kmemleak.txt | 14 +++++++++++++-
mm/kmemleak.c | 21 ++++++++++++++++-----
2 files changed, 29 insertions(+), 6 deletions(-)
diff -puN Documentation/kmemleak.txt~kmemleak-allow-freeing-internal-objects-after-kmemleak-was-disabled Documentation/kmemleak.txt
--- a/Documentation/kmemleak.txt~kmemleak-allow-freeing-internal-objects-after-kmemleak-was-disabled
+++ a/Documentation/kmemleak.txt
@@ -44,7 +44,8 @@ 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)
+ off - disable kmemleak, or free all kmemleak objects if kmemleak
+ has been disabled due to fatal errors. (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)
@@ -120,6 +121,17 @@ Then as usual to get your report with:
# cat /sys/kernel/debug/kmemleak
+Freeing kmemleak internal objects
+---------------------------------
+
+To allow access to previously found memory leaks even when an error fatal
+to kmemleak happens, internal kmemleak objects won't be freed in this case.
+Those objects may occupy a large part of physical memory.
+
+You can reclaim memory from those objects with:
+
+ # echo off > /sys/kernel/debug/kmemleak
+
Kmemleak API
------------
diff -puN mm/kmemleak.c~kmemleak-allow-freeing-internal-objects-after-kmemleak-was-disabled mm/kmemleak.c
--- a/mm/kmemleak.c~kmemleak-allow-freeing-internal-objects-after-kmemleak-was-disabled
+++ a/mm/kmemleak.c
@@ -1616,9 +1616,6 @@ static ssize_t kmemleak_write(struct fil
int buf_size;
int ret;
- if (!atomic_read(&kmemleak_enabled))
- return -EBUSY;
-
buf_size = min(size, (sizeof(buf) - 1));
if (strncpy_from_user(buf, user_buf, buf_size) < 0)
return -EFAULT;
@@ -1628,9 +1625,18 @@ static ssize_t kmemleak_write(struct fil
if (ret < 0)
return ret;
- if (strncmp(buf, "off", 3) == 0)
+ if (strncmp(buf, "off", 3) == 0) {
+ stop_scan_thread();
kmemleak_disable();
- else if (strncmp(buf, "stack=on", 8) == 0)
+ goto out;
+ }
+
+ if (!atomic_read(&kmemleak_enabled)) {
+ ret = -EBUSY;
+ goto out;
+ }
+
+ if (strncmp(buf, "stack=on", 8) == 0)
kmemleak_stack_scan = 1;
else if (strncmp(buf, "stack=off", 9) == 0)
kmemleak_stack_scan = 0;
@@ -1695,6 +1701,11 @@ static void kmemleak_do_cleanup(struct w
list_for_each_entry_rcu(object, &object_list, object_list)
delete_object_full(object->pointer);
rcu_read_unlock();
+ } else {
+ pr_info("Disable kmemleak without freeing internal objects, "
+ "so you may still check information on memory leak. "
+ "You may reclaim memory by writing \"off\" to "
+ "/sys/kernel/debug/kmemleak\n");
}
mutex_unlock(&scan_mutex);
}
_
Patches currently in -mm which might be from lizefan@xxxxxxxxxx are
origin.patch
kmemleak-allow-freeing-internal-objects-after-kmemleak-was-disabled.patch
kmemleak-remove-redundant-code.patch
kmemleak-change-some-global-variables-to-int.patch
kmemcheck-move-hook-into-__alloc_pages_nodemask-for-the-page-allocator.patch
linux-next.patch
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