linux-kernel - Re: [RFC PATCH 2/3] kmemleak: Add callbacks to the bootmem allocator

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Message-Id: <1247046231.6595.14.camel@pc1117.cambridge.arm.com>
Date:	Wed, 08 Jul 2009 10:43:51 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	Pekka Enberg <penberg@...helsinki.fi>
Cc:	Johannes Weiner <hannes@...xchg.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>
Subject: Re: [RFC PATCH 2/3] kmemleak: Add callbacks to the bootmem
	allocator

On Wed, 2009-07-08 at 09:48 +0300, Pekka Enberg wrote:
> On Tue, 2009-07-07 at 23:09 +0100, Catalin Marinas wrote:
> > On Tue, 2009-07-07 at 18:53 +0200, Johannes Weiner wrote:
> > > On Tue, Jul 07, 2009 at 10:08:50AM +0300, Pekka Enberg wrote:
> > > > On Mon, 2009-07-06 at 11:51 +0100, Catalin Marinas wrote:
> > > > > @@ -597,7 +601,9 @@ restart:
> > > > >  void * __init __alloc_bootmem_nopanic(unsigned long size, unsigned long align,
> > > > >  					unsigned long goal)
> > > > >  {
> > > > > -	return ___alloc_bootmem_nopanic(size, align, goal, 0);
> > > > > +	void *ptr =  ___alloc_bootmem_nopanic(size, align, goal, 0);
> > > > > +	kmemleak_alloc(ptr, size, 1, GFP_KERNEL);
> > > > > +	return ptr;
> > > 
> > > You may get an object from kzalloc() here, I don't think you want to
> > > track that (again), right?
> > 
> > You are write, I missed the alloc_arch_preferred_bootmem() function
> > which may call kzalloc().
> > 
> > > Pekka already worked out all the central places to catch 'slab already
> > > available' allocations, they can probably help you place the hooks.
> > 
> > It seems that alloc_bootmem_core() is central to all the bootmem
> > allocations. Is it OK to place the kmemleak_alloc hook only in this
> > function?
> 
> I think so. Johannes?

To get a better view, here's the complete patch:


kmemleak: Add callbacks to the bootmem allocator

From: Catalin Marinas <catalin.marinas@....com>

This patch adds kmemleak_alloc/free callbacks to the bootmem allocator.
This would allow scanning of such blocks and help avoiding a whole class
of false positives and more kmemleak annotations.

Signed-off-by: Catalin Marinas <catalin.marinas@....com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Pekka Enberg <penberg@...helsinki.fi>
---
 mm/bootmem.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/mm/bootmem.c b/mm/bootmem.c
index d2a9ce9..90f3ed0 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -335,6 +335,8 @@ void __init free_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
 {
 	unsigned long start, end;
 
+	kmemleak_free_part(__va(physaddr), size);
+
 	start = PFN_UP(physaddr);
 	end = PFN_DOWN(physaddr + size);
 
@@ -354,6 +356,8 @@ void __init free_bootmem(unsigned long addr, unsigned long size)
 {
 	unsigned long start, end;
 
+	kmemleak_free_part(__va(addr), size);
+
 	start = PFN_UP(addr);
 	end = PFN_DOWN(addr + size);
 
@@ -516,6 +520,7 @@ find_block:
 		region = phys_to_virt(PFN_PHYS(bdata->node_min_pfn) +
 				start_off);
 		memset(region, 0, size);
+		kmemleak_alloc(region, size, 1, 0);
 		return region;
 	}
 

-- 
Catalin

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