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 A85622045A1; Wed, 12 Feb 2025 22:56:07 +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=1739400967; cv=none; b=D3Clkz0cVICx2GPz2STiW9zE9vXhOqWNiNLoIuE4rm72hDoAupMGe+kuHBpxRPBWfE1iOaEKRvD0TJvTNDzbn8npPP7Ls/wVc6wRUEOb6acpNrH/8VhcUCvQqRGnjv3BZvmi0TKvid64MvboToiXEl1jv9NE6lOv1SotXZbDSiI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739400967; c=relaxed/simple; bh=/ixeuw+sP1h2HlhY+xFvfHUHI7nevOOg8s37LSTC0tI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=mzx8OfbDn1nB8e6BhYala7hfzWt2ayNLGZlFt5lMoSJssgVvKX+Oq8wFd8q5ICHyZYFlshGixq9L/CtLYvRSjljOnatk98DQKTHh3Dq0mNgfm+yT4CDB3wwFY4HidkaYz3fCvzEus3ZTXBdNyEtA2lFJjkPB5U0q+67BVI0bdLs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LqkU3JYR; 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="LqkU3JYR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 96B7AC4CEDF; Wed, 12 Feb 2025 22:56:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1739400967; bh=/ixeuw+sP1h2HlhY+xFvfHUHI7nevOOg8s37LSTC0tI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LqkU3JYRAbcPqbKej9sprTUJgj/cBZNUa+KqErDX9CnNGplxQ60VrA2ly+wwcOfk/ bMaIPZkIHYSe5FOoV09z1pbFnTX5s+ix+V75AYrZIBSd2bvm1QtGIqDwThZ9MyLN0r SKs3d1HXw1teBKyx9XGACfic1E36RQjOhn7qTgPWvtE6WeiH3mBh3TvwHoUc1kehFa itecSmpwrGQw+dijYNvt7/6HmlOuNYh4mvIE74NmNkkyxhx3RMSVG6SkUxmUVHebI2 LL4lh0GCvrxIEzOqPUR58mnO2nZaIocA6zUQUU5JZuV0NRKDGg2DxEdDyndf1GBXuv UCCQt81cDqKrw== Date: Wed, 12 Feb 2025 14:56:05 -0800 From: Namhyung Kim To: Ian Rogers Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Adrian Hunter , Kan Liang , Hao Ge , James Clark , Howard Chu , Dominique Martinet , Levi Yun , Xu Yang , Tengda Wu , Yang Jihong , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1 00/10] Move uid filtering to BPF filters Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Wed, Feb 12, 2025 at 12:00:42PM -0800, Ian Rogers wrote: > On Wed, Feb 12, 2025 at 10:46 AM Namhyung Kim wrote: > > It's not completely broken and works sometimes. > > No this is the definition of completely broken. If it only works > sometimes then you can't use it, we can't put a test on it, there is > no point in it. Even when it doesn't fail on perf_event_open, does it > work for processes that start after /proc is scanned? No, it is > completely broken. Ok, we have a different definition for it. Let's ignore the imaginary users of the broken features. Have you added a test for this change? Anyway I've tested your change and found some issues: 1. It silently exited when BPF-skel is not built. Better to put some messages at least. $ sudo ./perf record -u $(id -u) -- sleep 1 2. Even with BPF-skel, perf record doesn't work well. It did something but failed to get sample data for some reason. $ sudo ./perf record -u $(id -u) -- sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.045 MB perf.data ] Oh, I think you now need to pass -a because it now works in system-wide mode and drops samples for other users. 3. With BPF-skel, non-root users will see this. $ ./perf record -u $(id -u) -- sleep 1 cannot get fd for 'filters' map failed to set filter "BPF" on event cycles:P with 13 (Permission denied) I think it's confusing and better to tell user that you need to run 'perf record --setup-filter pin' as root first. But maybe due to the issue #2, you still need to run it as root. Thanks, Namhyung