From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6BC6DC6FD1C for ; Fri, 24 Mar 2023 15:03:59 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E4E146B0075; Fri, 24 Mar 2023 11:03:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E23B46B0078; Fri, 24 Mar 2023 11:03:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D3BC96B007B; Fri, 24 Mar 2023 11:03:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id C71036B0075 for ; Fri, 24 Mar 2023 11:03:58 -0400 (EDT) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 81DF3140AC3 for ; Fri, 24 Mar 2023 15:03:58 +0000 (UTC) X-FDA: 80604111756.28.3A99CF1 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf23.hostedemail.com (Postfix) with ESMTP id E8255140016 for ; Fri, 24 Mar 2023 15:03:53 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=UwCiahyM; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf23.hostedemail.com: domain of mkoutny@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=mkoutny@suse.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1679670234; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Rfr8g5aJSVUWobCiA6CGIV3Ux30dV0HPukLuzQZq+hk=; b=kzjE+MXkciQ3P6l9SoOofZa1DV22bmhFF0owMucLN0+dfiR7ml6Y85yj6vqc6c6MoinLjv +zh01yoThLfu4v0ZNVEmZXaVfEh60zHtBXohkPWzCXWUc6nREp7Qhn2BPpy01ekn071NIj TUu9z9ba3Iu7fUDfqJkeEaAtrOvaDzA= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=UwCiahyM; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf23.hostedemail.com: domain of mkoutny@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=mkoutny@suse.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1679670234; a=rsa-sha256; cv=none; b=RA0rvKTBGw0jNg815KTTkTMImtvonbcUU6Yal1XWsnK0oo9wagKeN1MFog52ZO8flQcdUF RIXs0dHvJemJho1JSykD9kBigdQmhr2KmezWRLxvG9O8B8mztgO5FioS4ZAOJQYKSMGpgG eD8XTRUa8EbUGbj/pRo4oW0OkZTizpI= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 891C81FEF6; Fri, 24 Mar 2023 15:03:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1679670232; h=from:from:reply-to: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=Rfr8g5aJSVUWobCiA6CGIV3Ux30dV0HPukLuzQZq+hk=; b=UwCiahyMAVG4lGGaeiI26S5FSNGq7lKd3cTtrlRbhbaTyWMfUVFS0L7PWKD2QauBv0p/I8 lB/cCsq1Be+SXtxVBk7V/yeSH2c5VS/0qOq4zqdmw2BI187JynDfaVlhM67l2q+WGdYnHh tbQhI2CEZSj5XRY2mooGLZOyrHgWw5k= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 55DCC138ED; Fri, 24 Mar 2023 15:03:52 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 838HFNi7HWS3XwAAMHmgww (envelope-from ); Fri, 24 Mar 2023 15:03:52 +0000 Date: Fri, 24 Mar 2023 16:03:50 +0100 From: Michal =?utf-8?Q?Koutn=C3=BD?= To: Florian Schmidt Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC] memcg v1: provide read access to memory.pressure_level Message-ID: <20230324150350.fu7itbqqvtjmyf3s@blackpad> References: <20230322142525.162469-1-flosch@nutanix.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="giw5phpov7yliruv" Content-Disposition: inline In-Reply-To: <20230322142525.162469-1-flosch@nutanix.com> X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: E8255140016 X-Stat-Signature: 9zpamjsfqax13fgpth5ws3xqbufq1ri9 X-HE-Tag: 1679670233-687117 X-HE-Meta: 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 UXhvorY8 Jb2LUWFV2MG2Mw+Z3Dj60C+Ds1zfihGBOrvMrwZEmDTXh0ti02/2NCCB0xV49lRglo90jj+pLKhbtU7dpRGo3vPandWei1iXryMFksifHVoQllu64AGqpk/hpLbD9OcP9FM1voKQa0t1Rkkh19g7l7q1mxC15VrgRfOVglKf5MjMwPF7gyAYbkoQrETOG2zXD3UWAHOyqS8lRq/qWk+I6Ze+8XRL3CSAyL7qacep00/nvqINhaEgnYQEcH1tAWmE/zQKbm7LD9NGfQ3GnI1P75Lm9WRRTrIqGX1szPXVD0dGUmhO1zhqQ+VZcD4zTMBnTzQAyn7grpipMa6xPUbdUwfux1CFyHcC53p50B9wa8/iqbrsVRqRxl6KBDDcy5MWh0Hn/fKAFRewPUB0Ez0YDcIrzrw0Y7y8q1M4AJQcWSGMCYVEpG+hUOyFcSg== 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: --giw5phpov7yliruv Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hello. On Wed, Mar 22, 2023 at 02:25:25PM +0000, Florian Schmidt wrote: > cgroups v1 has a unique way of setting up memory pressure notifications: =2E.. > There are several ways around this issue, but adding a dummy read > handler seems like the least invasive to me. I'd be interested to hear: > (a) do you think there is a less invasive way? Alternatively, we could > add a flag in cftype in include/linux/cgroup-defs.h, but that seems > more invasive for what is a legacy interface. You can (as privileged user) modify file perms in userspace first (e.g. chmod o+r memory.pressure_level) and then it can used by non-privileged users. (Or do LSM prevent you from that too?) > (b) would you be interested to take this patch, or is it too niche a fix > for a legacy subsystem? I'd rather not extend this "unique way" with additionally unique dummy helpers. My 0.02 =E2=82=AC, Michal --giw5phpov7yliruv Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQTrXXag4J0QvXXBmkMkDQmsBEOquQUCZB271AAKCRAkDQmsBEOq uaftAP9jAb8MRvyOlJlzSiA/74Dm588NNIhwB30zeAvi2Gy2DQD8Du97muUPss8S XDdnabKXH1krN1zbPtFwqMvvCx5e6wI= =7Q79 -----END PGP SIGNATURE----- --giw5phpov7yliruv--