Le lundi 26 septembre 2011 à 17:50 +0100, Catalin Marinas a écrit :
> 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);
>
Hmm, you need to call kmemleak_alloc() for each chunk allocated per
possible cpu.
Here is the (untested) patch for the allocation phase, need the same at
freeing time
diff --git a/mm/percpu-km.c b/mm/percpu-km.c
index 89633fe..5061ac5 100644
--- a/mm/percpu-km.c
+++ b/mm/percpu-km.c
@@ -37,9 +37,12 @@ static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size)
{
unsigned int cpu;
- for_each_possible_cpu(cpu)
- memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
+ for_each_possible_cpu(cpu) {
+ void *chunk_addr = (void *)pcpu_chunk_addr(chunk, cpu, 0) + off;
+ kmemleak_alloc(chunk_addr, size, 1, GFP_KERNEL);
+ memset(chunk_addr, 0, size);
+ }
return 0;
}
diff --git a/mm/percpu-vm.c b/mm/percpu-vm.c
index ea53496..0d397cc 100644
--- a/mm/percpu-vm.c
+++ b/mm/percpu-vm.c
@@ -342,8 +342,12 @@ static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size)
/* commit new bitmap */
bitmap_copy(chunk->populated, populated, pcpu_unit_pages);
clear:
- for_each_possible_cpu(cpu)
- memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
+ for_each_possible_cpu(cpu) {
+ void *chunk_addr = (void *)pcpu_chunk_addr(chunk, cpu, 0) + off;
+
+ kmemleak_alloc(chunk_addr, size, 1, GFP_KERNEL);
+ memset(chunk_addr, 0, size);
+ }
return 0;
err_unmap:
--
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