Re: kmemleak: Cannot insert 0xffff880007fedd28 into the objectsearch tree (already existing)

From: Catalin Marinas
Date: Wed May 09 2012 - 12:10:43 EST

On Sun, May 06, 2012 at 05:08:28PM +0100, Sami Liedes wrote:
> While trying to use kmemleak in KVM/x86-64 on mainline 3.3.4, I'm
> running into this error (whole preceding dmesg below):
> [ 2.251741] kmemleak: Cannot insert 0xffff880007fedd28 into the object search tree (already existing)
> ...
> [ 2.252016] kmemleak: Kernel memory leak detector disabled

It looks like its caused by the percpu memory allocations. The set up
areas must be freed but I only did it for SMP systems, forgot about UP.
Please find a patch below.

> I tested this on some older kernels too; at least v2.6.37 behaves the
> same, i.e. I get the same kmemleak error, though not the lockdep
> warnings.

This happens on the kmemleak disable path which is called with the
kmemleak_lock acquired. I'll have a look and move the clean-up thread
scheduling around.



commit 631d16e6284ddecd9d261f929582244f6757b678
Author: Catalin Marinas <catalin.marinas@xxxxxxx>
Date: Wed May 9 16:45:46 2012 +0100

kmemleak: Fix the kmemleak tracking of the percpu areas with !SMP

Kmemleak tracks the percpu allocations via a specific API and the
originally allocated areas must be removed from kmemleak (via
kmemleak_free). The code was already doing this for SMP systems.

Reported-by: Sami Liedes <sami.liedes@xxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>

diff --git a/mm/percpu.c b/mm/percpu.c
index f47af91..2daf6d5 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1885,6 +1885,8 @@ void __init setup_per_cpu_areas(void)
fc = __alloc_bootmem(unit_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
if (!ai || !fc)
panic("Failed to allocate memory for percpu areas.");
+ /* kmemleak tracks the percpu allocations separately */
+ kmemleak_free(fc);

ai->dyn_size = unit_size;
ai->unit_size = unit_size;

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