caba4cbbd2
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
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.