From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f179.google.com (mail-pl1-f179.google.com [209.85.214.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2481E3DDDBC for ; Thu, 16 Apr 2026 14:26:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776349600; cv=none; b=F7v4TnylbL7VC24u9h5lArg3V9uDPCpBVnaXMprxCT+H0iw6uvtMhLvp7kltrJfn4xvRDDnitk9zrOAgjJ9/0ZHoLfu7R2qwLirkylXRxe+UnvXNLzoJPRqCb3ANjhJjRSshwCvbYbNSgxcbE5fSJYtzfj9+M4erOQhaj2XpZcE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776349600; c=relaxed/simple; bh=we7FsVVr0iCNWOI0LJTVT73vYifP/TGImeutdDhrOYI=; h=Mime-Version:Content-Type:Date:Message-Id:Subject:From:To:Cc: References:In-Reply-To; b=GoRoyBcgn4doS4QyzNZecZKIwSUS1B6Da+dmpDsXG7bJOyh9Ls8qHMaJBKABXGMEaUUzfSvtPkOTQyESketijBbgq+mzG15fpc2ptgMdBknp3LEXFVKWOjQ98FCYiQA6eGr++O/3WWCqsWHHA/KlQWWsEoX0Fc379vRN9ar/wUM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=FshZ0Opr; arc=none smtp.client-ip=209.85.214.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="FshZ0Opr" Received: by mail-pl1-f179.google.com with SMTP id d9443c01a7336-2ab39b111b9so36665285ad.1 for ; Thu, 16 Apr 2026 07:26:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1776349598; x=1776954398; darn=vger.kernel.org; h=in-reply-to:references:cc:to:from:subject:message-id:date :content-transfer-encoding:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=XWF6xDBwzNdm18ji+1jjnivSj1pP6bYuXUs6j3C7prw=; b=FshZ0OpriZQA+reVf2+KzYBIxasehmIxASaDnij6S3DrkUZgd2ky6ru1rPk9NqKsZK MIzjIWpIhbu0KYj/vBxc4C1q82DNmnBa6ca437XubQ/bV5pYsCvULfERnIwwJqCRF8CE mtXU/SFVixCHR8/vbVn7CzUpYNYVKHsxwYnShnN3+RxK/auBdCt0JwPhBB68v9KucdtH 5Wa4+j8w5drJ+MKkzQPpP0s6SkhuYmsJ+L3YLhLI1Q1sHSXJrGuUnKFpJdxY7+cX/PG+ mQZazV8GWI2GRlp8drqDb+8E0x624FQnJahMJsdx/LzimVcF6Mqh9NFavh9S61tb5t2W Tt6g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776349598; x=1776954398; h=in-reply-to:references:cc:to:from:subject:message-id:date :content-transfer-encoding:mime-version:x-gm-gg:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=XWF6xDBwzNdm18ji+1jjnivSj1pP6bYuXUs6j3C7prw=; b=cAgLdwvFidJw7+nwdHfR2aGu54CkwStj/hstcJpf4SFYrQbKpiLEOb5wJMQ0WcV52l bo70PptXJ2SlWgf5MkBUmKtuf5/CSeG6irjKhhSvAavwAJmov8BBhD7oBgZrsBpKiGzE 2ufzcmo7mmnAjEBzkbk/HJCCVW6+o0HglSzaD/2Nr/6XIVHup81paTXdvBa5doljzxGQ jRA4VkxYHla6BC6iq5aXDWsJXcr+iYJmfkcM79JKi+WwYNqshM0TeG8ms3dQd5UjOw3w L0fmkP9+R8hHMeGmcdj4Hnn/KztMaNYgKutfNE7klookKVoIB1rgXdJFaqYnJ/Oagmc3 cghQ== X-Forwarded-Encrypted: i=1; AFNElJ+KGh4yAVIgkfosXJrnuvgkDmgohUpB83f66jLYsvUCczt8sTPX637lEVmg426XItAANB+qZ0cIQpOdx8Y=@vger.kernel.org X-Gm-Message-State: AOJu0YzCbdZnwUO1EAs/4BEaXCSb4rA13qRM5p9qKLYqHmVvLel67YhO 3C5dfN4IwojMudw/oyGQy30BcOQdQk34LQbfmRCXPOCil9tIgT2VtZi5 X-Gm-Gg: AeBDietptqNdIMpZpNB5TzRUCm/AwYcEyKVmD8R9ibS8BOmYvggcCRqmrcLlooYRFWw i/tpDMDsaO6p/7hde6ixmwt9zKpT2ntYRB3/AeQ2oJMW6s/Eg3g10c6qUJyuhSASvh3nOLJBoSa jdLSd0nOMl/9QQWM45oUmN+zWtmM7ZWmW3ZOM3sdCulng4GUhp/Yz9zszLGLE323wXgD8QPOJ/L 22+zaDyOrX+RkW9Si1OabMudZsjyyUi5CQrl+YH3haBMADqLWDVMoZ4SZZSqoS4v3UgihLlksNQ DQVECFtjg4NeD4lR7B/tDUkcIy1pxeETRD2nVhfNi1SNK8e51p89HFsvAsOI/oPAxJWD5nSfOih zUA6iEBj3OWGDjKS4S6PJlFR3pEjogqMaymrM7TN7zjLu+XY5N9JQm7+KSrTBu3o5MqncjhcEJa FG6xLi/UOlyjbqgjUxpssiQJ0cfNDmd1i13N1hBM/fpWsE2sunx+4D69DGL5sFC9lYNem1KDgVJ BmcDew1v/AieMQqFDZcFOTIJ1Iao8JxY2EFmhudwvn47gMF7gtnFl9r8TgaCoNPiXI= X-Received: by 2002:a17:903:320e:b0:2b0:606b:6fd3 with SMTP id d9443c01a7336-2b2d591d2e8mr245162915ad.5.1776349598297; Thu, 16 Apr 2026 07:26:38 -0700 (PDT) Received: from localhost ([2601:600:837f:c470:1879:8422:922b:e5d3]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b478142565sm57547615ad.37.2026.04.16.07.26.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 16 Apr 2026 07:26:37 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Thu, 16 Apr 2026 07:26:36 -0700 Message-Id: Subject: Re: [RFC] making nested spin_trylock() work on UP? From: "Alexei Starovoitov" To: "Vlastimil Babka (SUSE)" , "Harry Yoo (Oracle)" , "Matthew Wilcox" Cc: "Vlastimil Babka" , "Peter Zijlstra" , "Ingo Molnar" , "Will Deacon" , "Sebastian Andrzej Siewior" , "LKML" , "linux-mm@kvack.org" , "Linus Torvalds" , "Waiman Long" , "Mel Gorman" , "Steven Rostedt" , "Hao Li" , "Andrew Morton" , "Suren Baghdasaryan" , "Michal Hocko" , "Brendan Jackman" , "Johannes Weiner" , "Zi Yan" , "Christoph Lameter" , "David Rientjes" , "Roman Gushchin" X-Mailer: aerc 0.21.0 References: In-Reply-To: On Thu Apr 16, 2026 at 3:05 AM PDT, Vlastimil Babka (SUSE) wrote: >> I think we need a special spinlock type that wraps something like this >> and use them when spinlocks can be trylock'd in an unknown context: >> pcp lock, zone lock, per-node partial slab list lock, >> per-node barn lock, etc. > > Soudns like a lot of hassle for a niche config (SMP=3Dn) where nobody wou= ld > use e.g. bpf tracing anyway. We already have this in kmalloc_nolock(): > > /* > * See the comment for the same check in > * alloc_frozen_pages_nolock_noprof() > */ > if (IS_ENABLED(CONFIG_PREEMPT_RT) && (in_nmi() || in_hardirq())) > return NULL; > > It would be trivial to extend this to !SMP. However it wouldn't cover the > kprobe context. Any idea Alexei? Yeah. Totally fine with that. Certainly better than "special spinlock type"= .