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[198.145.29.99]) by mx.google.com with ESMTPS id n128si12027715pgn.82.2019.07.23.10.52.38 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 23 Jul 2019 10:52:38 -0700 (PDT) Received-SPF: pass (google.com: domain of jlayton@kernel.org designates 198.145.29.99 as permitted sender) client-ip=198.145.29.99; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=rduY142V; spf=pass (google.com: domain of jlayton@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=jlayton@kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from tleilax.poochiereds.net (cpe-71-70-156-158.nc.res.rr.com [71.70.156.158]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 74E752229A; Tue, 23 Jul 2019 17:52:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563904358; bh=nmc8uaRDy6gzgZmALXLogPzoQsDDnnuylDBBg1jtn1c=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=rduY142VQa1IsnoNlMdQo6TGmPN6qSG3GZUkSwSTd6A59arYA0evBnpSt3fmDAemz CkugF3lhK7nLyByuBN8u6yAmLgwlLNa501KqRSNFgeI5W55M+Tw7sOQqUQ4mptCv23 hbqbBoA5xQYu9iVktqkbMIy0z5Q0SabAWFEhYJvw= Message-ID: <3622a5fe9f13ddfd15b262dbeda700a26c395c2a.camel@kernel.org> Subject: Re: [PATCH] mm: check for sleepable context in kvfree From: Jeff Layton To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, lhenriques@suse.com, cmaiolino@redhat.com, Christoph Hellwig Date: Tue, 23 Jul 2019 13:52:36 -0400 In-Reply-To: <20190723131212.445-1-jlayton@kernel.org> References: <20190723131212.445-1-jlayton@kernel.org> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.32.4 (3.32.4-1.fc30) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, 2019-07-23 at 09:12 -0400, Jeff Layton wrote: > A lot of callers of kvfree only go down the vfree path under very rare > circumstances, and so may never end up hitting the might_sleep_if in it. > Ensure that when kvfree is called, that it is operating in a context > where it is allowed to sleep. > > Cc: Alexander Viro > Cc: Luis Henriques > Signed-off-by: Jeff Layton > --- > mm/util.c | 2 ++ > 1 file changed, 2 insertions(+) > FWIW, I started looking at this after Luis sent me some ceph patches that fixed a few of these problems. I have not done extensive testing with this patch, so maybe consider this an RFC for now. HCH points out that xfs uses kvfree as a generic "free this no matter what it is" sort of wrapper and expects the callers to work out whether they might be freeing a vmalloc'ed address. If that sort of usage turns out to be prevalent, then we may need another approach to clean this up. > diff --git a/mm/util.c b/mm/util.c > index e6351a80f248..81ec2a003c86 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -482,6 +482,8 @@ EXPORT_SYMBOL(kvmalloc_node); > */ > void kvfree(const void *addr) > { > + might_sleep_if(!in_interrupt()); > + > if (is_vmalloc_addr(addr)) > vfree(addr); > else -- Jeff Layton