On Mon, Sep 26, 2011 at 05:32:54PM +0100, Eric Dumazet wrote:
> Le lundi 26 septembre 2011 à 23:17 +0800, Huajun Li a écrit :
> > Memory leak detector gives following memory leak report, it seems the
> > report is triggered by net/core/flow.c, but actually, it should be a
> > false positive report.
> > So, is there any idea from kmemleak side to fix/disable this false
> > positive report like this?
> > Yes, kmemleak_not_leak(...) could disable it, but is it suitable for this case ?
...
> CC lkml and percpu maintainers (Tejun Heo & Christoph Lameter ) as well
>
> AFAIK this false positive only occurs if percpu data is allocated
> outside of embedded pcu space.
>
> (grep pcpu_get_vm_areas /proc/vmallocinfo)
>
> I suspect this is a percpu/kmemleak cooperation problem (a missing
> kmemleak_alloc() ?)
>
> I am pretty sure kmemleak_not_leak() is not the right answer to this
> problem.
kmemleak_not_leak() definitely not the write answer. The alloc_percpu()
call does not have any kmemleak_alloc() callback, so it doesn't scan
them.
Huajun, could you please try the patch below:
8<--------------------------------
kmemleak: Handle percpu memory allocation
From: Catalin Marinas <catalin.marinas@xxxxxxx>
This patch adds kmemleak callbacks from the percpu allocator, reducing a
number of false positives caused by kmemleak not scanning such memory
blocks.
Reported-by: Huajun Li <huajun.li.lee@xxxxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
---
mm/percpu.c | 11 +++++++++--
1 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/mm/percpu.c b/mm/percpu.c
index bf80e55..c47a90b 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -67,6 +67,7 @@
#include <linux/spinlock.h>
#include <linux/vmalloc.h>
#include <linux/workqueue.h>
+#include <linux/kmemleak.h>
#include <asm/cacheflush.h>
#include <asm/sections.h>
@@ -833,7 +834,9 @@ fail_unlock_mutex:
*/
void __percpu *__alloc_percpu(size_t size, size_t align)
{
- return pcpu_alloc(size, align, false);
+ void __percpu *ptr = pcpu_alloc(size, align, false);
+ kmemleak_alloc(ptr, size, 1, GFP_KERNEL);
+ return ptr;
}
EXPORT_SYMBOL_GPL(__alloc_percpu);
@@ -855,7 +858,9 @@ EXPORT_SYMBOL_GPL(__alloc_percpu);
*/
void __percpu *__alloc_reserved_percpu(size_t size, size_t align)
{
- return pcpu_alloc(size, align, true);
+ void __percpu *ptr = pcpu_alloc(size, align, true);
+ kmemleak_alloc(ptr, size, 1, GFP_KERNEL);
+ return ptr;
}
/**
@@ -915,6 +920,8 @@ void free_percpu(void __percpu *ptr)
if (!ptr)
return;
+ kmemleak_free(ptr);
+
addr = __pcpu_ptr_to_addr(ptr);
spin_lock_irqsave(&pcpu_lock, flags);
--
Catalin
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