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authorWaiman Long <longman@redhat.com>2017-08-14 09:52:13 -0400
committerThomas Gleixner <tglx@linutronix.de>2017-08-14 16:51:01 +0200
commitcaba4cbbd27d755572730801ac34fe063fc40a32 (patch)
tree71a5b42a697bbc4828ca7d2694f9ee8b90bdaade
parentef954844c7ace62f773f4f23e28d2d915adc419f (diff)
debugobjects: Make kmemleak ignore debug objects
The allocated debug objects are either on the free list or in the hashed bucket lists. So they won't get lost. However if both debug objects and kmemleak are enabled and kmemleak scanning is done while some of the debug objects are transitioning from one list to the others, false negative reporting of memory leaks may happen for those objects. For example, [38687.275678] kmemleak: 12 new suspected memory leaks (see /sys/kernel/debug/kmemleak) unreferenced object 0xffff92e98aabeb68 (size 40): comm "ksmtuned", pid 4344, jiffies 4298403600 (age 906.430s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 d0 bc db 92 e9 92 ff ff ................ 01 00 00 00 00 00 00 00 38 36 8a 61 e9 92 ff ff ........86.a.... backtrace: [<ffffffff8fa5378a>] kmemleak_alloc+0x4a/0xa0 [<ffffffff8f47c019>] kmem_cache_alloc+0xe9/0x320 [<ffffffff8f62ed96>] __debug_object_init+0x3e6/0x400 [<ffffffff8f62ef01>] debug_object_activate+0x131/0x210 [<ffffffff8f330d9f>] __call_rcu+0x3f/0x400 [<ffffffff8f33117d>] call_rcu_sched+0x1d/0x20 [<ffffffff8f4a183c>] put_object+0x2c/0x40 [<ffffffff8f4a188c>] __delete_object+0x3c/0x50 [<ffffffff8f4a18bd>] delete_object_full+0x1d/0x20 [<ffffffff8fa535c2>] kmemleak_free+0x32/0x80 [<ffffffff8f47af07>] kmem_cache_free+0x77/0x350 [<ffffffff8f453912>] unlink_anon_vmas+0x82/0x1e0 [<ffffffff8f440341>] free_pgtables+0xa1/0x110 [<ffffffff8f44af91>] exit_mmap+0xc1/0x170 [<ffffffff8f29db60>] mmput+0x80/0x150 [<ffffffff8f2a7609>] do_exit+0x2a9/0xd20 The references in the debug objects may also hide a real memory leak. As there is no point in having kmemleak to track debug object allocations, kmemleak checking is now disabled for debug objects. Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/1502718733-8527-1-git-send-email-longman@redhat.com
-rw-r--r--init/main.c2
-rw-r--r--lib/debugobjects.c3
2 files changed, 4 insertions, 1 deletions
diff --git a/init/main.c b/init/main.c
index 052481fbe363..7ec20cf7b111 100644
--- a/init/main.c
+++ b/init/main.c
@@ -651,8 +651,8 @@ asmlinkage __visible void __init start_kernel(void)
}
#endif
page_ext_init();
- debug_objects_mem_init();
kmemleak_init();
+ debug_objects_mem_init();
setup_per_cpu_pageset();
numa_policy_init();
if (late_time_init)
diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index 17afb0430161..2f5349c6e81a 100644
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -18,6 +18,7 @@
#include <linux/debugfs.h>
#include <linux/slab.h>
#include <linux/hash.h>
+#include <linux/kmemleak.h>
#define ODEBUG_HASH_BITS 14
#define ODEBUG_HASH_SIZE (1 << ODEBUG_HASH_BITS)
@@ -110,6 +111,7 @@ static void fill_pool(void)
if (!new)
return;
+ kmemleak_ignore(new);
raw_spin_lock_irqsave(&pool_lock, flags);
hlist_add_head(&new->node, &obj_pool);
debug_objects_allocated++;
@@ -1080,6 +1082,7 @@ static int __init debug_objects_replace_static_objects(void)
obj = kmem_cache_zalloc(obj_cache, GFP_KERNEL);
if (!obj)
goto free;
+ kmemleak_ignore(obj);
hlist_add_head(&obj->node, &objects);
}