From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 34386192B90 for ; Mon, 27 Jan 2025 19:37:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738006674; cv=none; b=Z3z8Qycb4iidmPPWXMGKzHd6X0aH4CxEmpJYjrQHVzVFYSimeD+tixOXcB/gxjDzvh1uAzk7DTta71iXNo6+JV2Rm91WKZmo16ab4XBcBmcIdHGETRl2H8U/X7sg32oF4JajJ0DYfp/emTt6Hde+vgSjA2+zUmrTn6kvVeA3vWI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738006674; c=relaxed/simple; bh=foxA2L/+4FGqo1Ez7fCuuER5N09cKkuLdZQCMwdNYAA=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=eK3eG5BsozdNxrwlorXcJAR5mlbXSIrWGdOxOxMgZKyC2uIHPH9YHWcqxc5x8hUQmNkHSup7EthNK5Oo7u9DUjzWX61jdSph6l1wGa1iZ9qwkKcyB2rbPxnjBT+yn6cKR9ZiE0GqblFgRCVgMc06IZ6S+m8V+oCpJ3IV0nXIJhE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cO1cU+5v; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="cO1cU+5v" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E63AEC4CED2; Mon, 27 Jan 2025 19:37:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1738006672; bh=foxA2L/+4FGqo1Ez7fCuuER5N09cKkuLdZQCMwdNYAA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=cO1cU+5vTzW2agjQTfHHy8UsXV5DsiAHlZcibNrFp6GkYxx/wOrWS48LeumK1INUN vQKZwmtMLArNLRYMz0vp62Mr0YERO9a2XX1Rw3ICTmzdhXkvzlZoPovAKCuxmXktMe N0S818gJEJyaegEDnNYwfZ6q5EXBbg+x4kMHRRV+ZKtqez1ZNyjs9peD6ztTkGyvMw 7AZ8SQNEvDflUwyqDGA6gcAkNTRfxslno/gd59qfpp4GNOROwcUgkLGgYy9RRYDect 1Atmh59yPDK1GpubmuMkC1Ecjn6nF82qQzqzCHmsq5OTfpfI/cVtYDRyQFqldS0sG8 LaTsT58CCYy3w== Date: Mon, 27 Jan 2025 11:37:50 -0800 From: Jakub Kicinski To: Toke =?UTF-8?B?SMO4aWxhbmQtSsO4cmdlbnNlbg==?= Cc: Mina Almasry , davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, andrew+netdev@lunn.ch, horms@kernel.org, hawk@kernel.org, ilias.apalodimas@linaro.org, asml.silence@gmail.com, kaiyuanz@google.com, willemb@google.com, mkarsten@uwaterloo.ca, jdamato@fastly.com Subject: Re: [PATCH net] net: page_pool: don't try to stash the napi id Message-ID: <20250127113750.54ed83d4@kernel.org> In-Reply-To: <877c6gpen5.fsf@toke.dk> References: <20250123231620.1086401-1-kuba@kernel.org> <87r04rq2jj.fsf@toke.dk> <877c6gpen5.fsf@toke.dk> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Mon, 27 Jan 2025 14:31:10 +0100 Toke H=C3=B8iland-J=C3=B8rgensen wrote: > > + > > +/* page_pool_destroy or page_pool_disable_direct_recycling must be > > called before > > + * netif_napi_del if pool->p.napi is set. > > + */ FWIW the comment is better placed on the warning, that's where people will look when they hit it ;) > > void page_pool_destroy(struct page_pool *pool); > > void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(= void *), > > const struct xdp_mem_info *mem); > > > > diff --git a/net/core/page_pool.c b/net/core/page_pool.c > > index 5c4b788b811b..dc82767b2516 100644 > > --- a/net/core/page_pool.c > > +++ b/net/core/page_pool.c > > @@ -1161,6 +1161,8 @@ void page_pool_destroy(struct page_pool *pool) > > if (!page_pool_put(pool)) > > return; > > > > + DEBUG_NET_WARN_ON(pool->p.napi && !napi_is_valid(pool->p.napi)); IDK what "napi_is_valid()" is. I think like this: diff --git a/net/core/page_pool.c b/net/core/page_pool.c index a3de752c5178..837ed36472db 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -1145,6 +1145,7 @@ void page_pool_disable_direct_recycling(struct page_p= ool *pool) * pool and NAPI are unlinked when NAPI is disabled. */ WARN_ON(!test_bit(NAPI_STATE_SCHED, &pool->p.napi->state)); + WARN_ON(!test_bit(NAPI_STATE_LISTED, &pool->p.napi->state)); WARN_ON(READ_ONCE(pool->p.napi->list_owner) !=3D -1); =20 WRITE_ONCE(pool->p.napi, NULL); Because page_pool_disable_direct_recycling() must also be called while NAPI is listed. Technically we should also sync rcu if the driver calls this directly, because NAPI may be reused :( > > page_pool_disable_direct_recycling(pool); > > page_pool_free_frag(pool); =20 >=20 > Yeah, good idea; care to send a proper patch? :) ...for net-next ? :)