From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta8.messagelabs.com (mail6.bemta8.messagelabs.com [216.82.243.55]) by kanga.kvack.org (Postfix) with ESMTP id 8C5599000BD for ; Mon, 26 Sep 2011 12:54:21 -0400 (EDT) Date: Mon, 26 Sep 2011 17:50:24 +0100 From: Catalin Marinas Subject: Re: Question about memory leak detector giving false positive report for net/core/flow.c Message-ID: <20110926165024.GA21617@e102109-lin.cambridge.arm.com> References: <1317054774.6363.9.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1317054774.6363.9.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> Sender: owner-linux-mm@kvack.org List-ID: To: Eric Dumazet Cc: Huajun Li , "linux-mm@kvack.org" , netdev , linux-kernel , Tejun Heo , Christoph Lameter On Mon, Sep 26, 2011 at 05:32:54PM +0100, Eric Dumazet wrote: > Le lundi 26 septembre 2011 a 23:17 +0800, Huajun Li a ecrit : > > 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 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 Signed-off-by: Catalin Marinas --- 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 #include #include +#include #include #include @@ -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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org