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From: David Howells <dhowells@redhat.com>
In-Reply-To: <9872f991-56a8-4915-b9b0-53accd6db0ef@moroto.mountain>
References: <9872f991-56a8-4915-b9b0-53accd6db0ef@moroto.mountain>
To: Dan Carpenter <dan.carpenter@linaro.org>
Cc: dhowells@redhat.com, Jeff Layton <jlayton@kernel.org>,
    linux-cachefs@redhat.com, linux-fsdevel@vger.kernel.org,
    linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [PATCH] netfs, fscache: Prevent Oops in fscache_put_cache()
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Content-ID: <1788107.1704913300.1@warthog.procyon.org.uk>
Date: Wed, 10 Jan 2024 19:01:40 +0000
Message-ID: <1788108.1704913300@warthog.procyon.org.uk>

Dan Carpenter <dan.carpenter@linaro.org> wrote:

>  	zero = __refcount_dec_and_test(&cache->ref, &ref);
> -	trace_fscache_cache(debug_id, ref - 1, where);
> +	trace_fscache_cache(cache->debug_id, ref - 1, where);

You can't do that if !zero.  cache may be deallocated between the two lines.

David