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 03692535B7; Tue, 18 Jun 2024 17:02:11 +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=1718730132; cv=none; b=anvBHksIX96r0cRHttzJnbwp5W93HptJKM0vBt2k9bg51syC/HusYa7E7Evl8SXnwrON2YdIk+cEGclU+ZKOH/YvU57ct7/6zDcZRG4fmx+RA26pBBG6KRjeXQ/NA2pu/WoXYsVaNM1Xf6NTx6jJ8Wy4pMTdaX2UyjYczaBn8P8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718730132; c=relaxed/simple; bh=Rox7hA3gEwDHsn/OtUndZMrIzG+7ua2p/cM8oQWxptQ=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=lDrjPstuHHXFR7DfVNfBXRpZ/qrC/jOpzoZvB9EbJi7jttCqtQqBgFZejPLtgatnSJ2rJpuDd1TAEfRYJygzMLECaJ3JUIesueI6cDLhcrMQGNr2GtWmgT61autCSSzMO7yyk2ywRePjtgiY+Wt/aPzOGhZgULXStOYGojnUYe4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lqiTNqGm; 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="lqiTNqGm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3BB60C3277B; Tue, 18 Jun 2024 17:02:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1718730131; bh=Rox7hA3gEwDHsn/OtUndZMrIzG+7ua2p/cM8oQWxptQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=lqiTNqGmp9YJy0CJ++0aR/ANGIbUd6+Rz9Yk0YX2ufigeeK5dFV3exaZ0nOTUMy11 4IZO1NMgy+9W3HMJusq9FdpLbm0Vw4b5PM4Dq9QOcGIYm2Gky9MO4ZdcDc0Lwi8S/R cjDJ1Dgt4yFZP7UmlHPxJS9BvSdQk62mBEpZIUKTzPHy9VSpD/19dMrNFrnWt6pKP7 4awak0TP0y99eYxiHvn/rBQhImzbMUEUVyh7mLYupiQN9VC7CgzuMSv3LHzdCkQFm5 gWgjY9BrqHRtSlaTMKOv8zsZO0Ys0U0cTUAiITraLL3nR1iR9HvcYh8MiZJaDtCepi hiEWT2vz1FXMw== Date: Tue, 18 Jun 2024 10:02:10 -0700 From: Jakub Kicinski To: "Paul E. McKenney" Cc: Paolo Abeni , Dmitry Safonov <0x7f454c46@gmail.com>, "netdev@vger.kernel.org" , rcu@vger.kernel.org Subject: Re: [TEST] TCP MD5 vs kmemleak Message-ID: <20240618100210.16c028e1@kernel.org> In-Reply-To: References: <20240617072451.1403e1d2@kernel.org> <20240618074037.66789717@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 18 Jun 2024 09:42:35 -0700 Paul E. McKenney wrote: > > FTR, with mptcp self-tests we hit a few kmemleak false positive on RCU > > freed pointers, that where addressed by to this patch: > > > > commit 5f98fd034ca6fd1ab8c91a3488968a0e9caaabf6 > > Author: Catalin Marinas > > Date: Sat Sep 30 17:46:56 2023 +0000 > > > > rcu: kmemleak: Ignore kmemleak false positives when RCU-freeing objects > > > > I'm wondering if this is hitting something similar? Possibly due to > > lazy RCU callbacks invoked after MSECS_MIN_AGE??? Dmitry mentioned this commit, too, but we use the same config for MPTCP tests, and while we repro TCP AO failures quite frequently, mptcp doesn't seem to have failed once. > Fun! ;-) > > This commit handles memory passed to kfree_rcu() and friends, but > not memory passed to call_rcu() and friends. Of course, call_rcu() > does not necessarily know the full extent of the memory passed to it, > for example, if passed a linked list, call_rcu() will know only about > the head of that list. > > There are similar challenges with synchronize_rcu() and friends. To be clear I think Dmitry was suspecting kfree_rcu(), he mentioned call_rcu() as something he was expecting to have a similar issue but it in fact appeared immune.