linux-kernel - Re: [PATCH 01/15] kmemleak: Add the base support

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Message-Id: <20081201170807.C2E2.E1E9C6FF@jp.fujitsu.com>
Date:	Mon, 01 Dec 2008 17:11:59 +0900
From:	Yasunori Goto <y-goto@...fujitsu.com>
To:	"Catalin Marinas" <catalin.marinas@....com>
Cc:	linux-kernel@...r.kernel.org, "Ingo Molnar" <mingo@...e.hu>,
	"Pekka Enberg" <penberg@...helsinki.fi>
Subject: Re: [PATCH 01/15] kmemleak: Add the base support

> Hi!
> 
> On Mon, Dec 1, 2008 at 7:39 AM, Yasunori Goto <y-goto@...fujitsu.com> wrote:
> >> +/*
> >> + * Insert a pointer into the pointer hash table.
> >> + */
> >> +static inline void create_object(unsigned long ptr, size_t size, int ref_count)
> >> +{
> >> +     unsigned long flags;
> >> +     struct memleak_object *object;
> >> +     struct prio_tree_node *node;
> >> +     struct stack_trace trace;
> >> +
> >> +     object = kmem_cache_alloc(object_cache, GFP_ATOMIC);
> >> +     if (!object)
> >> +             panic("kmemleak: cannot allocate a memleak_object structure\n");
> >
> > IIRC, GFP_ATOMIC allocation sometimes fails. (ex. when page cache occupies all
> > area). It seems to be easy to panic. Is it intended?
> 
> Yup, GFP_ATOMIC can fail as can any memory allocation on out-of-memory
> conditions unless you specify GFP_NOFAIL which will either succeed or
> lock up the box. I think you can just WARN_ON() here? However, it's
> probably safer to pass gfp flags from the callers here; otherwise we
> end up doing tons of GFP_ATOMIC allocations which is not healthy in
> general.

I agree. It is reasonable to pass gfp flag from the caller.

Thanks.

> 
> Also, I see some other BUG_ON() calls in the code which probably
> should be converted to WARN_ON() as well.

-- 
Yasunori Goto 


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