From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dvalin.narfation.org (dvalin.narfation.org [213.160.73.56]) (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 958883A1BB; Wed, 12 Jun 2024 18:23:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.160.73.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718216583; cv=none; b=gsRuEKmiHutLoOc4dQ4kSnx00T1Kn+usgn2U8dV8LuKkhx4GFObw6zS1K8YLLSjk+rV90j6ZpcOjdlnw6rrnhlR/vL/UaC5w3LfujfhbdUoadE6OLfu7JXJhI0v+SbTLn0av/0xML3yvPsPqfyR/UiwEGEApfTd01W/ZCUZnbuU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718216583; c=relaxed/simple; bh=S/fn4KpsKyYIb7wyOqQFmHywMa1Mz95vU/XpulFss3s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=RS2ooC/e0SAmuiOAzlAyXVdq4FCcXRXp0LO0UqPiBw51GreX+UiyS1hgZUOJAkVEdu+s4Wsk1KKcrxlBinJit1voScVUtjQt4tHRvVxH2G+YqDLDy3tk67PQfxYpdvQMTTUvTeAuS2gXx6BA/p/6jOWOnYe6RrvwHPW9ujKhI4A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=narfation.org; spf=pass smtp.mailfrom=narfation.org; dkim=pass (1024-bit key) header.d=narfation.org header.i=@narfation.org header.b=iX4SAKjS; arc=none smtp.client-ip=213.160.73.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=narfation.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=narfation.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=narfation.org header.i=@narfation.org header.b="iX4SAKjS" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=narfation.org; s=20121; t=1718216572; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=r2DIMPyxXsUsx3z3UHNDfQvmHitGXJiStJK05XL6M2Q=; b=iX4SAKjS85UNGwt2lkaEQqSxCKTvFY5YqaV5lR5uo6cmb3yqiPqSy0QTNp06jX/47CgtUt gAs50cZL2EXRva9Xf0iAnCBIhRpgC+JEqUqNnjqVVm/4Kb3sCo4e2qiroY/jdGH1zwk4e7 fzTxXeRhTjT6C0prhAE+4lu0OZ+Sxu0= From: Sven Eckelmann To: "Paul E. McKenney" , b.a.t.m.a.n@lists.open-mesh.org Cc: b.a.t.m.a.n@lists.open-mesh.org, Dmitry Antipov , netdev@vger.kernel.org, rcu@vger.kernel.org, Linus =?ISO-8859-1?Q?L=FCssing?= Subject: Re: [PATCH] Revert "batman-adv: prefer kfree_rcu() over call_rcu() with free-only callbacks" Date: Wed, 12 Jun 2024 20:22:49 +0200 Message-ID: <2328482.ElGaqSPkdT@sven-l14> In-Reply-To: References: <20240612133357.2596-1-linus.luessing@c0d3.blue> <020489fa-26a3-422c-8924-7dc71f23422c@paulmck-laptop> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart4898629.GXAFRqVoOG"; micalg="pgp-sha512"; protocol="application/pgp-signature" --nextPart4898629.GXAFRqVoOG Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="iso-8859-1"; protected-headers="v1" From: Sven Eckelmann Date: Wed, 12 Jun 2024 20:22:49 +0200 Message-ID: <2328482.ElGaqSPkdT@sven-l14> In-Reply-To: MIME-Version: 1.0 On Wednesday, 12 June 2024 18:31:57 CEST Linus L=FCssing wrote: > On Wed, Jun 12, 2024 at 09:06:25AM -0700, Paul E. McKenney wrote: > > We are looking into nice ways of solving this, but in the meantime, > > yes, if you are RCU-freeing slab objects into a slab that is destroyed > > at module-unload time, you currently need to stick with call_rcu() > > and rcu_barrier(). > > > > We do have some potential solutions to allow use of kfree_rcu() with > > this sort of slab, but they are still strictly potential. > > > > Apologies for my having failed to foresee this particular trap! >=20 > No worries, thanks for the help and clarification! This at least > restored my sanity, was starting to doubt my understanding of RCU > and the batman-adv code the longer I tried to find the issue in > batman-adv :D. Thanks Linus and Paul. I've queued up the revert. But feel free to submit a= =20 version with updated text in case you want to incorporate information from= =20 this thread. Kind regards, Sven --nextPart4898629.GXAFRqVoOG Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part. Content-Transfer-Encoding: 7Bit -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQS81G/PswftH/OW8cVND3cr0xT1ywUCZmnnegAKCRBND3cr0xT1 y/2ZAQCJLtdWIbCPUrkTqkI9mv1ThzM/ZcLceVmbFSKhVCSe8AEAtVQx2GE9aUCk S1OPFkU0m5zCxxMHHIygDnw3SwaMvAA= =mD28 -----END PGP SIGNATURE----- --nextPart4898629.GXAFRqVoOG--