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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 02392C678D4 for ; Fri, 3 Mar 2023 01:15:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229822AbjCCBPF (ORCPT ); Thu, 2 Mar 2023 20:15:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53218 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229816AbjCCBOL (ORCPT ); Thu, 2 Mar 2023 20:14:11 -0500 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DAFA8231D1 for ; Thu, 2 Mar 2023 17:13:50 -0800 (PST) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-536a4eba107so8210607b3.19 for ; Thu, 02 Mar 2023 17:13:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1677806030; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=Pk7Od9lx1FvwXfe2+jCyuETO6j4UmvCkXNRwPfsPdX8=; b=eawrTzCH33CbOpQRrdHF07gcS0h9D1fZAptzT+SJUwp8eltvWzEvvp9uSp3iqVbkls cqD96AeE8qiN73slqQ81HuGUu6xBeCHlD/QwFmF4SWXenGr98sEL5df8aqUJgveG2cZA MIRo5Gf6PS8V7+p93ejwhwPx/Zzm8icHjBpOJpQ5mT/DzAHhN1Ua/6fBWtLOS3kr55VC 3GEyDVbXsOkpLx5aJClCUXvSUnC7JOuxd2OR/Zbimj6cGtSwn7Ad4+TroPZDrDw3oBbW 2cUbgCSfRfZTug//WxNgmYlh8jp6snpqjyp3oQIgg1RyVqOYyxrglI95cfpAy3GN3cnZ CAJw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1677806030; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=Pk7Od9lx1FvwXfe2+jCyuETO6j4UmvCkXNRwPfsPdX8=; b=KrhHYqQrgYZkxDy7x/byKKCdfL5JNBzZqwd5kkUlY8satwaIAb+kJhCxcnZf8zARxB AAnS+y1PQv35l/kqrwC3MZZGy53gYtNENU34lUpZ5g+KvjpfxhO7wPyS081hM816pmom sC+Hvy1P6HPiuuPbxiC/JUC3up6+3trVSRaiAWKAhFTAyxRO8RBr95SOegIVu1p0z1VN V1exWctGWAhrK6Ufs3GdP1X8dELQSU2klqd0m3B8YprKvuQwzuz0j3a0V51qO7i+4Zly +Ed82uBpO4hALK1iCJMlF8hQNH5Nq0uxCM6ehuiPYov/c6y3cXTlc4cHWCQRmo63Kayn H8eg== X-Gm-Message-State: AO0yUKW1e9WNgW7uAfUCzSEEzuXja170ZTj3Mk4sIe3831H7YksyxL6I BqtPRPvyG3tLp8u9x6aEUlAnxGVYj0A= X-Google-Smtp-Source: AK7set85a9u2TpY4EKigfXzI8OCBp4gfZp5TC44x/oTa8B6mXZ19XkruqBUD6Y1l4ByN/bQmQq0C7M2NxnI= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:200:58cd:2543:62b7:a517]) (user=surenb job=sendgmr) by 2002:a05:6902:344:b0:8a3:d147:280b with SMTP id e4-20020a056902034400b008a3d147280bmr2337965ybs.3.1677806030055; Thu, 02 Mar 2023 17:13:50 -0800 (PST) Date: Thu, 2 Mar 2023 17:13:46 -0800 Mime-Version: 1.0 X-Mailer: git-send-email 2.40.0.rc0.216.gc4246ad0f0-goog Message-ID: <20230303011346.3342233-1-surenb@google.com> Subject: [PATCH v2 1/1] psi: remove 500ms min window size limitation for triggers From: Suren Baghdasaryan To: tj@kernel.org Cc: hannes@cmpxchg.org, lizefan.x@bytedance.com, peterz@infradead.org, johunt@akamai.com, mhocko@suse.com, keescook@chromium.org, quic_sudaraja@quicinc.com, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, surenb@google.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Current 500ms min window size for psi triggers limits polling interval to 50ms to prevent polling threads from using too much cpu bandwidth by polling too frequently. However the number of cgroups with triggers is unlimited, so this protection can be defeated by creating multiple cgroups with psi triggers (triggers in each cgroup are served by a single "psimon" kernel thread). Instead of limiting min polling period, which also limits the latency of psi events, it's better to limit psi trigger creation to authorized users only, like we do for system-wide psi triggers (/proc/pressure/* files can be written only by processes with CAP_SYS_RESOURCE capability). This also makes access rules for cgroup psi files consistent with system-wide ones. Add a CAP_SYS_RESOURCE capability check for cgroup psi file writers and remove the psi window min size limitation. Suggested-by: Sudarshan Rajagopalan Link: https://lore.kernel.org/all/cover.1676067791.git.quic_sudaraja@quicinc.com/ Signed-off-by: Suren Baghdasaryan Acked-by: Michal Hocko Acked-by: Johannes Weiner --- kernel/cgroup/cgroup.c | 10 ++++++++++ kernel/sched/psi.c | 4 +--- 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 935e8121b21e..b600a6baaeca 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -3867,6 +3867,12 @@ static __poll_t cgroup_pressure_poll(struct kernfs_open_file *of, return psi_trigger_poll(&ctx->psi.trigger, of->file, pt); } +static int cgroup_pressure_open(struct kernfs_open_file *of) +{ + return (of->file->f_mode & FMODE_WRITE && !capable(CAP_SYS_RESOURCE)) ? + -EPERM : 0; +} + static void cgroup_pressure_release(struct kernfs_open_file *of) { struct cgroup_file_ctx *ctx = of->priv; @@ -5266,6 +5272,7 @@ static struct cftype cgroup_psi_files[] = { { .name = "io.pressure", .file_offset = offsetof(struct cgroup, psi_files[PSI_IO]), + .open = cgroup_pressure_open, .seq_show = cgroup_io_pressure_show, .write = cgroup_io_pressure_write, .poll = cgroup_pressure_poll, @@ -5274,6 +5281,7 @@ static struct cftype cgroup_psi_files[] = { { .name = "memory.pressure", .file_offset = offsetof(struct cgroup, psi_files[PSI_MEM]), + .open = cgroup_pressure_open, .seq_show = cgroup_memory_pressure_show, .write = cgroup_memory_pressure_write, .poll = cgroup_pressure_poll, @@ -5282,6 +5290,7 @@ static struct cftype cgroup_psi_files[] = { { .name = "cpu.pressure", .file_offset = offsetof(struct cgroup, psi_files[PSI_CPU]), + .open = cgroup_pressure_open, .seq_show = cgroup_cpu_pressure_show, .write = cgroup_cpu_pressure_write, .poll = cgroup_pressure_poll, @@ -5291,6 +5300,7 @@ static struct cftype cgroup_psi_files[] = { { .name = "irq.pressure", .file_offset = offsetof(struct cgroup, psi_files[PSI_IRQ]), + .open = cgroup_pressure_open, .seq_show = cgroup_irq_pressure_show, .write = cgroup_irq_pressure_write, .poll = cgroup_pressure_poll, diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c index 02e011cabe91..0945f956bf80 100644 --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -160,7 +160,6 @@ __setup("psi=", setup_psi); #define EXP_300s 2034 /* 1/exp(2s/300s) */ /* PSI trigger definitions */ -#define WINDOW_MIN_US 500000 /* Min window size is 500ms */ #define WINDOW_MAX_US 10000000 /* Max window size is 10s */ #define UPDATES_PER_WINDOW 10 /* 10 updates per window */ @@ -1278,8 +1277,7 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group, if (state >= PSI_NONIDLE) return ERR_PTR(-EINVAL); - if (window_us < WINDOW_MIN_US || - window_us > WINDOW_MAX_US) + if (window_us == 0 || window_us > WINDOW_MAX_US) return ERR_PTR(-EINVAL); /* Check threshold */ -- 2.40.0.rc0.216.gc4246ad0f0-goog