netdev - Re: [PATCH v4 0/3] mm, treewide: Rename kzfree() to kfree

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Date:   Wed, 17 Jun 2020 10:03:30 +0200
From:   Jo -l <joel.voyer@...il.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     dsterba@...e.cz, Joe Perches <joe@...ches.com>,
        Waiman Long <longman@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Howells <dhowells@...hat.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        David Rientjes <rientjes@...gle.com>,
        Michal Hocko <mhocko@...e.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        "Jason A. Donenfeld" <Jason@...c4.com>, linux-mm@...ck.org,
        keyrings@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
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Subject: Re: [PATCH v4 0/3] mm, treewide: Rename kzfree() to kfree_sensitive()

Bonjour,
Désolé, aucune traduction possible, 
En français pour comprendre!
Merci
slts

> Le 17 06 2020 à 02:37, Matthew Wilcox <willy@...radead.org> a écrit :
> 
> On Wed, Jun 17, 2020 at 01:01:30AM +0200, David Sterba wrote:
>> On Tue, Jun 16, 2020 at 11:53:50AM -0700, Joe Perches wrote:
>>> On Mon, 2020-06-15 at 21:57 -0400, Waiman Long wrote:
>>>> v4:
>>>> - Break out the memzero_explicit() change as suggested by Dan Carpenter
>>>>  so that it can be backported to stable.
>>>> - Drop the "crypto: Remove unnecessary memzero_explicit()" patch for
>>>>  now as there can be a bit more discussion on what is best. It will be
>>>>  introduced as a separate patch later on after this one is merged.
>>> 
>>> To this larger audience and last week without reply:
>>> https://lore.kernel.org/lkml/573b3fbd5927c643920e1364230c296b23e7584d.camel@perches.com/
>>> 
>>> Are there _any_ fastpath uses of kfree or vfree?
>> 
>> I'd consider kfree performance critical for cases where it is called
>> under locks. If possible the kfree is moved outside of the critical
>> section, but we have rbtrees or lists that get deleted under locks and
>> restructuring the code to do eg. splice and free it outside of the lock
>> is not always possible.
> 
> Not just performance critical, but correctness critical.  Since kvfree()
> may allocate from the vmalloc allocator, I really think that kvfree()
> should assert that it's !in_atomic().  Otherwise we can get into trouble
> if we end up calling vfree() and have to take the mutex.

Jo-l
joel.voyer@...il.com