From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.15]) (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 D46EA3D3CE2; Fri, 27 Mar 2026 08:16:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.15 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774599402; cv=none; b=u1zHaIihdCTy6+vVTXzVjiPaxawtKdbMU5ITn2BtSfCgJr6xK1WnV/qKE03mSr53BduZ5v6Yvnl5HRZCGnFVpQkCngpUvs5k9ZSroA4B2sQvWUpbTIPDTWh26GdwLIcrrHyHtsaLjjq+RP4+2IisPWD4teFXFOJMZnKEmEaYrz8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774599402; c=relaxed/simple; bh=qeVWa8r7f4q+L+gXinu2pi9ngSyC1Swgdgb8weA16QE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=a1I87N7Qe/qgcX5i6FGo2u8E7QVnf8boFInW4LvARMFjLXdyApc8Z2WKOVQoo8C/KRWBgDZsLgikKOyFWYG8UHP13F58QoUFlQ+yi47iqvGWJBQaBtch+YlC4AbNXxNKY8mNdiohClBdQ6rzgBi2jp5aSAmG6X77tQJC0nlUDDg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=eY+9MLoE; arc=none smtp.client-ip=192.198.163.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="eY+9MLoE" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1774599400; x=1806135400; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=qeVWa8r7f4q+L+gXinu2pi9ngSyC1Swgdgb8weA16QE=; b=eY+9MLoEt7lonn2S0RKrSwDKQHlrVNSfz1jSuRZ5yfkJO6jxqdGJqXIO hU4Mjghm0UnRJmgVTV2RJbOylg2JNOOYfKGUTjOEeYFVm2e2aT9Adt5GY v/+b/40BbMLmLC8INFxEMeuziwWBnd6GscIBV+aK0yBWDzRty+cwCIDCL oMoeL+DfqJOQeBXbaTg2cYF0TpsCpByob290y4Gvhey/oIqshcMk1b6xB pfcZVCOEqeC8Uk3e1+IqoMbQJKoDEG8m/71T2v6sh033MNkFpuW1timlA Mf7c3ZA2OdC+HpHjJRyIljoC0eKGbCwk7OaHZT6rVQLHPu07ExFLlUZee Q==; X-CSE-ConnectionGUID: IgebWfR3Rn2BF5bkBMyQTg== X-CSE-MsgGUID: aCLoj+RLQ5yqef9pbhW2BA== X-IronPort-AV: E=McAfee;i="6800,10657,11741"; a="75784035" X-IronPort-AV: E=Sophos;i="6.23,143,1770624000"; d="scan'208";a="75784035" Received: from orviesa002.jf.intel.com ([10.64.159.142]) by fmvoesa109.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Mar 2026 01:16:39 -0700 X-CSE-ConnectionGUID: GKBuzr8rT1imynU1RhvNpw== X-CSE-MsgGUID: dir45kgJQ6GnreQLIax5Cg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.23,143,1770624000"; d="scan'208";a="255747888" Received: from egrumbac-mobl6.ger.corp.intel.com (HELO fedora) ([10.245.244.146]) by orviesa002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Mar 2026 01:16:34 -0700 From: =?UTF-8?q?Thomas=20Hellstr=C3=B6m?= To: intel-xe@lists.freedesktop.org Cc: =?UTF-8?q?Thomas=20Hellstr=C3=B6m?= , Natalie Vock , Johannes Weiner , Tejun Heo , =?UTF-8?q?Michal=20Koutn=C3=BD?= , cgroups@vger.kernel.org, Huang Rui , Matthew Brost , Matthew Auld , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Simona Vetter , David Airlie , =?UTF-8?q?Christian=20K=C3=B6nig?= , Alex Deucher , Rodrigo Vivi , dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/5] cgroup/dmem: Return error when setting max below current usage Date: Fri, 27 Mar 2026 09:15:56 +0100 Message-ID: <20260327081600.4885-2-thomas.hellstrom@linux.intel.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260327081600.4885-1-thomas.hellstrom@linux.intel.com> References: <20260327081600.4885-1-thomas.hellstrom@linux.intel.com> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Return -EBUSY to userspace when writing dmem.max below the cgroup's current device memory usage, rather than silently leaving the limit unchanged. Assisted-by: GitHub Copilot:claude-sonnet-4.6 Signed-off-by: Thomas Hellström --- kernel/cgroup/dmem.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/kernel/cgroup/dmem.c b/kernel/cgroup/dmem.c index 9d95824dc6fa..3e6d4c0b26a1 100644 --- a/kernel/cgroup/dmem.c +++ b/kernel/cgroup/dmem.c @@ -144,22 +144,24 @@ static void free_cg_pool(struct dmem_cgroup_pool_state *pool) dmemcg_pool_put(pool); } -static void +static int set_resource_min(struct dmem_cgroup_pool_state *pool, u64 val) { page_counter_set_min(&pool->cnt, val); + return 0; } -static void +static int set_resource_low(struct dmem_cgroup_pool_state *pool, u64 val) { page_counter_set_low(&pool->cnt, val); + return 0; } -static void +static int set_resource_max(struct dmem_cgroup_pool_state *pool, u64 val) { - page_counter_set_max(&pool->cnt, val); + return page_counter_set_max(&pool->cnt, val); } static u64 get_resource_low(struct dmem_cgroup_pool_state *pool) @@ -726,7 +728,7 @@ static int dmemcg_parse_limit(char *options, struct dmem_cgroup_region *region, static ssize_t dmemcg_limit_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off, - void (*apply)(struct dmem_cgroup_pool_state *, u64)) + int (*apply)(struct dmem_cgroup_pool_state *, u64)) { struct dmemcg_state *dmemcs = css_to_dmemcs(of_css(of)); int err = 0; @@ -773,7 +775,7 @@ static ssize_t dmemcg_limit_write(struct kernfs_open_file *of, } /* And commit */ - apply(pool, new_limit); + err = apply(pool, new_limit); dmemcg_pool_put(pool); out_put: -- 2.53.0