From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 90B663644A7 for ; Mon, 12 Jan 2026 17:14:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768238085; cv=none; b=WiT388NwGu4fp+NeV1BJu0TcfXMDdoRGJ0hdq2tMEXHmmELwyDOGjTJVEIkpPbo3Y7hekBdY26UxtL8+79AU8qjIHo5YjO8pqUjUVEV2iIlUJFVS5i69WzYssjV8k3ftku7vlV+4U5UaiCC5HZIkNkjpV6u1cVzMmmomHKZqznE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768238085; c=relaxed/simple; bh=p2RIxY5fGlPnWZZI5ZaSHBVwyZ9upWMBTdLTBFx8kA8=; h=From:Message-ID:Date:MIME-Version:Subject:To:Cc:References: In-Reply-To:Content-Type; b=NbVcAWaEg98MgztdvzgkuUGYutbQS9FSs5enAzWQzLpCk3kfYw1PPJ6zbgzKWkYAplr+6bIr510JUoTXPTLyIVCpFHs/03lBMGQ49kgez7yU5uUbysjh2PQnGwLFhhm4musOEk1bLNIwqQmvFS0kPTe+mPfampdq9KXpcFJu+uI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=Tcc6V0nV; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=lWAqSeST; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Tcc6V0nV"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="lWAqSeST" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1768238083; h=from:from: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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=niuwlukY4G5Spngj6ahATQFt383vhuD9uikDSg5CgGU=; b=Tcc6V0nV3vCyC0Djb/xVddfcJuZB98Da91PStdJhoZImgO4iadVpMowTXlve5+jUzt45Iz 6+qSZKO4nB8swuLC3SzcVYqOEHl5TEJJSGQF+3nMitewhYcGtrB0Gq4cTy4gWWz71cAe+r uFnvTi8P3d2Pv5JGa9bxmJ1t3GwotP0= Received: from mail-vk1-f197.google.com (mail-vk1-f197.google.com [209.85.221.197]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-528-pQqqqO7ZMX-nWHHeLHyWAg-1; Mon, 12 Jan 2026 12:14:37 -0500 X-MC-Unique: pQqqqO7ZMX-nWHHeLHyWAg-1 X-Mimecast-MFC-AGG-ID: pQqqqO7ZMX-nWHHeLHyWAg_1768238077 Received: by mail-vk1-f197.google.com with SMTP id 71dfb90a1353d-56366d9ed8dso3331902e0c.0 for ; Mon, 12 Jan 2026 09:14:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1768238077; x=1768842877; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:content-language:references :cc:to:subject:user-agent:mime-version:date:message-id:from:from:to :cc:subject:date:message-id:reply-to; bh=niuwlukY4G5Spngj6ahATQFt383vhuD9uikDSg5CgGU=; b=lWAqSeSTRIOIzfMsz4mrT85y/jOrhJFVSvom/qo/BhR8ZFZgRSGvWYCqEaOClrYsar vDlauFsWWywchY84RdW2txrlUHo6w7dd1Hwpv3RAX2gorEhVVoA/SNsSaXxKc/KSQSq5 KRZ7vEF/md9pi/ToMs19pweLdPtwjvC+coX/IFftu3UP3MTW/GVpkVpPtZ76a/CfWZur fyJMjqJRCVj5/V3wBMaKLiuW7lpAkc69IH+gb32Qmd05GNOBjoMzN5KpyZKhxxA27wF8 qRo02u8NB/l5SPqtDN1eYiKP+lc3UKA3uAzjolbEa7XgS72TOEjnqNmhm1yw4kJmMbM+ +rzQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1768238077; x=1768842877; h=content-transfer-encoding:in-reply-to:content-language:references :cc:to:subject:user-agent:mime-version:date:message-id:from:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=niuwlukY4G5Spngj6ahATQFt383vhuD9uikDSg5CgGU=; b=mfRf9vAL81D/ve5IQw/Cw3WuBkl7y2IQftBBBSs1qAW+bSSzyTChv9hTQCfhqzSPGX J1J2tL0NbC4MyIwR4/wxsK6XWFA/UY8a252ocGnrYbV5UnasKJrc37KHm+Z1hJ5gGDfW j+4nKaCwkNT+pC1zCcwyZJ49GI4c4zXspggV8Tgp/uPnqn9Z3sKfhqNQyZ0+BfsO8EKw sIWi0muf3b6+DWh5zERPRFERxme3ap83iYSbMc1WK/MQZzjvgm+YGzcBzMV4i1Gn2KKU nOImNUm9a1hJP+4LrnPWyiP5KaDeCz1uV3BG64k9k0p10e/teIz/vnxqh1YwVwBNndV2 KTkA== X-Forwarded-Encrypted: i=1; AJvYcCXKjfi/6RuEk9OrK9vQP2qwKKTndatH8yUCfQGkciBI/S60RuRrImOpQoZn+PpMibOfTM+aJUqA4Bk37VI=@vger.kernel.org X-Gm-Message-State: AOJu0YyNvRntPNc1IywO9+8LTXghtj/i/a0obPFoGExni66KYq+fiBR3 R4PPCa8M5r4zCwE/gj6umLYor7E7KXmGeJ6Ye3QmObRE/ZsrfSoo/9VXeKKNP2BVJEpr29ie3FG ELU9ntF/rY5IX1ViWIbFIUYkhP+Ad2Lx513KxJFD1NFqV5NP58tnYXiy5JijtlVu8oA== X-Gm-Gg: AY/fxX7kdyDxMHk7W0kAApLZuXAofLsWv54DKuluCtm1YL3Zw7chu/hfNabntzETtem m9TZmjiBWaNfBY1hlij2pMHwgd5YHEKR2v3aImgAj8FJAh4M83ALnA0XkAZxZKQQGj2HWugB2LH IcSxc582re44+Nsfijd79l+KcqYBZ4nB748EkuOQn+MFZe/KWkAw0f73W9Be1IqWzK9IAlclU/I jeBLu987z8lFC5h8Y+eBXQMh53MGeBW6UvLidXpiJryKDg+V/NnNEchytR25QCFOAR/PdoPDW3G tSsg6AkprrUlfzHmXyEFPyElTCfroqSBDl7ZqtZX6LIWgGsU+hqCueYRolBJ6pHyZIafr4AP3Ft zOJBpD9dHTrzmOcVA2VWdkSPzOka+33+Y3SX+jrTTssGz0JWhL3o0PmsB X-Received: by 2002:a05:6122:2887:b0:55b:305b:4e3e with SMTP id 71dfb90a1353d-56347ffb9edmr5814836e0c.20.1768238076672; Mon, 12 Jan 2026 09:14:36 -0800 (PST) X-Google-Smtp-Source: AGHT+IFlqbRNk7nmg9s0QyR3wuxXiH+S603lyrhRY4LiNHJf7Z/PHgn/i4o1R+LczeMDwvDVUwoqOg== X-Received: by 2002:a05:6122:2887:b0:55b:305b:4e3e with SMTP id 71dfb90a1353d-56347ffb9edmr5814824e0c.20.1768238076243; Mon, 12 Jan 2026 09:14:36 -0800 (PST) Received: from ?IPV6:2601:188:c102:b180:1f8b:71d0:77b1:1f6e? ([2601:188:c102:b180:1f8b:71d0:77b1:1f6e]) by smtp.gmail.com with ESMTPSA id 71dfb90a1353d-56374ba06efsm7016541e0c.11.2026.01.12.09.14.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 12 Jan 2026 09:14:35 -0800 (PST) From: Waiman Long X-Google-Original-From: Waiman Long Message-ID: <5f4bfd8b-8699-4bef-bf49-f29965e95ca4@redhat.com> Date: Mon, 12 Jan 2026 12:14:30 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] irqchip/gic-v3-its: Don't acquire rt_spin_lock in allocate_vpe_l1_table() To: Thomas Gleixner , Waiman Long , Marc Zyngier Cc: Sebastian Andrzej Siewior , Clark Williams , Steven Rostedt , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev References: <20260107215353.75612-1-longman@redhat.com> <864iowmrx6.wl-maz@kernel.org> <87ms2nsqju.ffs@tglx> <86wm1qlq7l.wl-maz@kernel.org> <87ecnwij44.ffs@tglx> <86v7h8l9ht.wl-maz@kernel.org> <40cec799-f363-4642-969b-24f5a2d56dfb@redhat.com> <87cy3eg94y.ffs@tglx> Content-Language: en-US In-Reply-To: <87cy3eg94y.ffs@tglx> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/12/26 10:09 AM, Thomas Gleixner wrote: > On Sun, Jan 11 2026 at 18:02, Waiman Long wrote: >> On 1/11/26 5:38 AM, Marc Zyngier wrote: >>>> Also that patch seems to be incomplete because there is another >>>> allocation further down in allocate_vpe_l1_table().... >>> Yeah, I wondered why page allocation wasn't affected by this issue, >>> but didn't try to find out. >> The use of GFP_ATOMIC flag in the page allocation request may help it to >> dip into the reserved area and avoid taking any spinlock. In my own >> test, just removing the kzalloc() call is enough to avoid any invalid >> context warning. In the page allocation code, there is a zone lock and a >> per_cpu_pages lock. They were not acquired in my particular test case, >> though further investigation may be needed to make sure it is really safe. > They might be acquired though. Only alloc_pages_nolock() guarantees that > no lock is taken IIRC. Thanks for the suggestion. I will look into using that for page allocation. I had actually attempt to use kmalloc_nolock() to replace kzalloc() initially. Even though it removed the call to rmqueue(), but there were other spinlocks in the slub code that were still being acquired like the local_lock() or the spinlock in the get_random() code. So I gave up using that. Anyway, kmalloc_nolock() doesn't seem to be fully working yet. Cheers, Longman