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Fri, 03 Feb 2023 06:27:14 -0800 (PST) Date: Fri, 3 Feb 2023 14:27:09 +0000 From: Hyeonggon Yoo <42.hyeyoo@gmail.com> To: Greg Kroah-Hartman Cc: linux-mm@kvack.org, Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Vlastimil Babka , Roman Gushchin , linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/slub: fix memory leak with using debugfs_lookup() Message-ID: References: <20230202142022.2300096-1-gregkh@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230202142022.2300096-1-gregkh@linuxfoundation.org> X-Stat-Signature: okfejnkgns6nfh9ahgd1dejxwzqjku47 X-Rspam-User: X-Rspamd-Queue-Id: F4149100011 X-Rspamd-Server: rspam06 X-HE-Tag: 1675434436-390779 X-HE-Meta: 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 PNgx081K 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 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 Thu, Feb 02, 2023 at 03:20:22PM +0100, Greg Kroah-Hartman wrote: > When calling debugfs_lookup() the result must have dput() called on it, > otherwise the memory will leak over time. To make things simpler, just > call debugfs_lookup_and_remove() instead which handles all of the logic > at once. > > Cc: Christoph Lameter > Cc: Pekka Enberg > Cc: David Rientjes > Cc: Joonsoo Kim > Cc: Andrew Morton > Cc: Vlastimil Babka > Cc: Roman Gushchin > Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Greg Kroah-Hartman > --- > mm/slub.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/slub.c b/mm/slub.c > index 13459c69095a..4880e461fcc5 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -6449,7 +6449,7 @@ static void debugfs_slab_add(struct kmem_cache *s) > > void debugfs_slab_release(struct kmem_cache *s) > { > - debugfs_remove_recursive(debugfs_lookup(s->name, slab_debugfs_root)); > + debugfs_lookup_and_remove(s->name, slab_debugfs_root); > } Looks good to me. Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Thank you for fixing this. > static int __init slab_debugfs_init(void) > -- > 2.39.1 >