From: Al Viro <viro@zeniv.linux.org.uk>
To: Christian Brauner <brauner@kernel.org>
Cc: Dmitry Antipov <dmantipov@yandex.ru>,
Catalin Marinas <catalin.marinas@arm.com>,
Joel Fernandes <joel@joelfernandes.org>,
linux-fsdevel@vger.kernel.org, lvc-project@linuxtesting.org
Subject: Re: [PATCH] [RFC] fs: prefer kfree_rcu() in fasync_remove_entry()
Date: Fri, 9 Feb 2024 16:36:46 +0000 [thread overview]
Message-ID: <20240209163646.GD608142@ZenIV> (raw)
In-Reply-To: <20240209-hierzu-getrunken-0b1a3bfc7d16@brauner>
On Fri, Feb 09, 2024 at 03:22:15PM +0100, Christian Brauner wrote:
> On Fri, Feb 09, 2024 at 03:52:19PM +0300, Dmitry Antipov wrote:
> > In 'fasync_remove_entry()', prefer 'kfree_rcu()' over 'call_rcu()' with dummy
> > 'fasync_free_rcu()' callback. This is mostly intended in attempt to fix weird
> > https://syzkaller.appspot.com/bug?id=6a64ad907e361e49e92d1c4c114128a1bda2ed7f,
> > where kmemleak may consider 'fa' as unreferenced during RCU grace period. See
> > https://lore.kernel.org/stable/20230930174657.800551-1-joel@joelfernandes.org
> > as well. Comments are highly appreciated.
> >
> > Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
> > ---
>
> Yeah, according to commit ae65a5211d90 ("mm/slab: document kfree() as
> allowed for kmem_cache_alloc() objects") this is now guaranteed to work
> for kmem_cache_alloc() objects since slab is gone. So independent of
> syzbot this seems like a decent enough cleanup.
Sure, but we'd better make very sure that it does *NOT* get picked by any
-stable prior to 6.4.
next prev parent reply other threads:[~2024-02-09 16:36 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-09 12:52 [PATCH] [RFC] fs: prefer kfree_rcu() in fasync_remove_entry() Dmitry Antipov
2024-02-09 14:21 ` Christian Brauner
2024-02-09 14:22 ` Christian Brauner
2024-02-09 16:36 ` Al Viro [this message]
2024-02-12 9:59 ` Christian Brauner
2024-02-09 16:35 ` Al Viro
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