debugobjects-make-kmemleak-ignore-debug-objects.patch removed from -mm tree

The patch titled
Subject: debugobjects: make kmemleak ignore debug objects
has been removed from the -mm tree. Its filename was
debugobjects-make-kmemleak-ignore-debug-objects.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: Waiman Long <[email protected]>
Subject: 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.

---

 init/main.c        |    2 +-
 lib/debugobjects.c |    3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff -puN init/main.c~debugobjects-make-kmemleak-ignore-debug-objects init/main.c
@@ -659,8 +659,8 @@ asmlinkage __visible void __init start_k
 		initrd_start = 0;
 	}
 #endif
-	debug_objects_mem_init();
 	kmemleak_init();
+	debug_objects_mem_init();
 	setup_per_cpu_pageset();
 	numa_policy_init();
 	if (late_time_init)

diff -puN lib/debugobjects.c~debugobjects-make-kmemleak-ignore-debug-objects 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_
 		obj = kmem_cache_zalloc(obj_cache, GFP_KERNEL);
 		if (!obj)
 			goto free;
+		kmemleak_ignore(obj);
 		hlist_add_head(&obj->node, &objects);
 	}
 

_

Patches currently in -mm which might be from [email protected] are