linux-kernel - Re: [PATCH RT] mm/slub: close possible memory-leak in kmem_cache_alloc

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Message-ID: <20171213145044.falrw5jsskq2ocha@linutronix.de>
Date:   Wed, 13 Dec 2017 15:50:44 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Jesper Dangaard Brouer <brouer@...hat.com>
Cc:     linux-rt-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        tglx@...utronix.de, Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Vladimir Davydov <vdavydov@...tuozzo.com>, linux-mm@...ck.org,
        Rao Shoaib <rao.shoaib@...cle.com>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: Re: [PATCH RT] mm/slub: close possible memory-leak in
 kmem_cache_alloc_bulk()

On 2017-12-13 15:46:54 [+0100], Jesper Dangaard Brouer wrote:
> > Jesper: There are no users of kmem_cache_alloc_bulk() and kfree_bulk().
> > Only kmem_cache_free_bulk() is used since it was introduced. Do you
> > think that it would make sense to remove those?
> 
> I would like to keep them.
> 
> Rao Shoaib (Cc'ed) is/was working on a patchset for RCU-bulk-free that
> used the kfree_bulk() API.
> 
> I plan to use kmem_cache_alloc_bulk() in the bpf-map "cpumap", for bulk
> allocating SKBs during dequeue of XDP frames.  (My original bulk alloc
> SKBs use-case during NAPI/softirq was never merged).

I see. So it may gain users in future you say.

> I've not seen free_delayed() before... and my cscope cannot find it...
It is PREEMPT RT only, mainline is not affected (that is why there is a
RT next to the PATCH in subject).

Sebastian