From nobody Mon Jun 15 15:09:29 2026 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.4]) (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 D7D0F28504D for ; Sat, 11 Apr 2026 00:42:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.4 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775868125; cv=none; b=iJj5eKbXqfr8Kr1JfFteFgZYYjMO5Ni9e2XeEJtFhPMidxAzhMXI/6N4h7HVlh1slVGSpzkGIXjDzEJL5mfgE4Oq4daY2zjiJDoHvG8QWCArvo5gzWxk8SOqZgwwatd9ngV5K8Av0KZD2ruEy1ojhHyrlpbbc8f5tt/il4rd47g= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775868125; c=relaxed/simple; bh=ViGhzYBOGZaYD3h3dn/bBCB8lM2aIoSWNNIO3SQpYH8=; h=From:Date:Subject:To:Cc:Message-Id; b=T2Ijr2qw4UM05Hv9d8VADmT4zI7zGYaQ0wFP44XM04bqcZvw8MVPM/7dq+i4i6yEUzlZTgogG30PleoVcZ5E0uaBGBbGxhVDGBGulSlTWX3urcbXIZAWXWWD9Qnlf2t4pRmf0Yrrqb7Df2IdECz2ok8ihvvPahkpFijUossgjGg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=SuxLlLqw; arc=none smtp.client-ip=220.197.31.4 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="SuxLlLqw" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:Date:Subject:To:Message-Id; bh=LqQbOTjchPFW0lx 0diS4zLD6NACWGtcyXD7tO/V579Q=; b=SuxLlLqw+Td/57FTB1tSArh+Z6lRqsr CjcKbnzc4ppQX57CJYdypVF3dxvyB5f3U0/+3c9PpfUxywcNhLBIs5f8EbGL94gp 6bfVG0OLZ6x5vtaKqOZX6vfBvy5KVSg2XgSAA1wwlUm4Jr+zAPFw1PfgBUzi+AIT T4s4xT0/IOWI= Received: from 229.199.16.172.in-addr.arpa (unknown []) by gzga-smtp-mtada-g0-4 (Coremail) with SMTP id _____wDXXhOsmNlpr8fUEQ--.24708S2; Sat, 11 Apr 2026 08:41:20 +0800 (CST) From: Cao Ruichuang Date: Sat, 11 Apr 2026 08:41:15 +0800 Subject: [PATCH] x86/itmt: Keep ITMT enabled when debugfs is unavailable To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org Cc: H. Peter Anvin , linux-kernel@vger.kernel.org Message-Id: <177586807597.24344.18258178378471533912@163.com> X-CM-TRANSID: _____wDXXhOsmNlpr8fUEQ--.24708S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7Cry7Kr47Zw15CryUKr1rZwb_yoW8tFy8pw 1q9w45Wry8trnxKFW3Ar48ZFyrA397Zry7Wrsru3yxZw15Jr1rWr18CF4avFZxWa1UCrWS yr1Yka42gr15tFJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07jorWrUUUUU= X-CM-SenderInfo: pfuht3jhqyimi6rwjhhfrp/xtbC6BEjXGnZmLGzQAAA3s Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" SCHED_MC_PRIO should not depend on DEBUG_FS for its runtime behavior. debugfs_create_file*() intentionally returns -ENODEV when CONFIG_DEBUG_FS is disabled so callers can distinguish "debugfs unavailable" from a real error. sched_set_itmt_support() currently treats that case as fatal and returns an error before enabling ITMT support. As a result, systems built with SCHED_MC_PRIO=3Dy and DEBUG_FS=3Dn silently lose ITMT scheduling support even though the two debugfs files created in itmt.c are only a debug toggle and a debug view of core priorities. Treat -ENODEV from the debugfs helpers as "no debugfs support" and keep going. Continue to fail on real debugfs creation errors. Reported-by: akinzler Link: https://bugzilla.kernel.org/show_bug.cgi?id=3D220638 Signed-off-by: Cao Ruichuang --- arch/x86/kernel/itmt.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/itmt.c b/arch/x86/kernel/itmt.c index 243a769fdd9..c3e40df7da7 100644 --- a/arch/x86/kernel/itmt.c +++ b/arch/x86/kernel/itmt.c @@ -100,6 +100,8 @@ static struct dentry *dfs_sched_core_prio; */ int sched_set_itmt_support(void) { + int ret; + guard(mutex)(&itmt_update_mutex); =20 if (sched_itmt_capable) @@ -110,16 +112,29 @@ int sched_set_itmt_support(void) arch_debugfs_dir, &sysctl_sched_itmt_enabled, &dfs_sched_itmt_fops); - if (IS_ERR_OR_NULL(dfs_sched_itmt)) { + if (IS_ERR(dfs_sched_itmt)) { + ret =3D PTR_ERR(dfs_sched_itmt); dfs_sched_itmt =3D NULL; + if (ret !=3D -ENODEV) + return ret; + } else if (!dfs_sched_itmt) { return -ENOMEM; } =20 dfs_sched_core_prio =3D debugfs_create_file("sched_core_priority", 0644, arch_debugfs_dir, NULL, &sched_core_priority_fops); - if (IS_ERR_OR_NULL(dfs_sched_core_prio)) { + if (IS_ERR(dfs_sched_core_prio)) { + ret =3D PTR_ERR(dfs_sched_core_prio); dfs_sched_core_prio =3D NULL; + if (ret !=3D -ENODEV) { + debugfs_remove(dfs_sched_itmt); + dfs_sched_itmt =3D NULL; + return ret; + } + } else if (!dfs_sched_core_prio) { + debugfs_remove(dfs_sched_itmt); + dfs_sched_itmt =3D NULL; return -ENOMEM; } =20 --=20 2.39.5 (Apple Git-154)