From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qv1-f48.google.com (mail-qv1-f48.google.com [209.85.219.48]) (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 AE7C51A2390 for ; Mon, 24 Feb 2025 04:49:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.48 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740372565; cv=none; b=kL0DIN7h5spw8IKstHUqfCAnh6jqIztLl3X48UkS3QBraSlVuqljYX1GcwPpd+07y3q38JRYOiUB6Btayeqnt5JL+bnnBuRwd0FeIYxLL0iV/tOyZde8cDUdmtojIlFd16fod7bxXr+pLGy6xMvNlFrXZXFKYQ/LauEDmDcZfTU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740372565; c=relaxed/simple; bh=m+ya0m48Hy05uufbgBSlRUASp/gEt5wNCSXXagY3Veo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=nfDO4XNVmfEkdgNKB5Vk+kdgU1v1paZ0k5QmHFzPJLBivK3/WmsLbSu6Qd/EwMikaJktcnMRbHSnbawu+2v1wqaeJdwni2GOiB8TX4ko0p9TvjLMuznM6a+YHgMB3jOV/mxxnlhMJ7S5LGhWUo3FM2zlSqWggBkVauYD419DK/Q= 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=HA3FZe0K; arc=none smtp.client-ip=209.85.219.48 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="HA3FZe0K" Received: by mail-qv1-f48.google.com with SMTP id 6a1803df08f44-6e6698667c7so51092766d6.2 for ; Sun, 23 Feb 2025 20:49:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1740372562; x=1740977362; darn=lists.linux.dev; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:feedback-id:from:to:cc:subject:date :message-id:reply-to; bh=ZytZEk8JtOudqPt3UiEgxftAzf8RUB8NEf9J511wOpk=; b=HA3FZe0KR9pYpsehwW7/KgGvsU5j4LlORo3f4US9JZWFz1RjgsO4kMXPl8nkOrRxrA BLMHczIBqoTjP0psHa2FGdPZsWfQ+xjpZPwPASjJO4MqhgYhdX6gi3Hd9hHdymde4HVM HKQIQVTIjGJupJ+L5CGCzOCcHVSOWUReLypEmsXRCARTZrZmljzyrGHT6++PYzB93u5m xDaF9EJEvu1iaH4v3RmoBs49RR2U9T6vxyOaS6dXnroGhhMogvEb7h8mz4ngZ05glziO 49Zy8zKxKAkhahQ0kZKE58/IAdu68MlRKHHmm+HkEdJbH8+CWuUQkNBNpPlt3wTai2nm Kqmw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1740372562; x=1740977362; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:feedback-id:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=ZytZEk8JtOudqPt3UiEgxftAzf8RUB8NEf9J511wOpk=; b=xQajuijhuY/0B9XC/FMpkP3SJgMGywAccFyOGjxMQ0ipcZlwNgdE6ZUbj6REmA6ds9 gb4f9JAdBEumML7fleWidK/YP2wh58UnVjNX7zLMOwFJBfAg7K1oDo5MlXDrnai6SKXn Hbtt3vTF1EatogIOy5fJyuvdS1/rnP2jYSScpNuHE1p53nQCs2sKELHWzY7M+VrxBhmM sRM4TDy3dPudzOXoHGnqDNy3jhyzSKAHqg8fzvgggALXmWHp15zcnII72Re0npMzqy2B 6awsPriEHAMNUWnbe/ct/cCKzsQfqyQ91bqxsJK3Fj1f6LeKqCGaIMl5oFNYeSxciqx/ MdYA== X-Forwarded-Encrypted: i=1; AJvYcCUXWkWPi4AoJpmN/zq8rs1dXJYr7Hc2paJ3k4Hs8L2s317/Onxb/UoSwCZhnGhQNY9AUsPx5yI=@lists.linux.dev X-Gm-Message-State: AOJu0YzuY52F9+81YVzQyXf87fFf3VheVs1MWWi3pPIt5+nGQ9jL0ZLP OVNk1e4gWYI5yMK4lLcV+drrb/5QER8kIy4lf4V91WCN+bbIzkOyowSv/g== X-Gm-Gg: ASbGncuQFxlX6FNFc3v4ajkkFVGvtpTl5EDb7Xqum1yt+UD13rTj6FF9/AhnkHIpDzw 1Q7g9bP1LotW06VxRjqD+Lyk5us4Hr2RZiYCuqb4c0vrf5CREnH2WQZ55uBI3EvYtrAvKVz7Ncb hnMQ99yILMjXCkVpF+axQ+o4b78O+Ww6Bdb0uI5vzStkPkxONE8cztN9mknAUVaz+pHMI3rxJ6I 1kI3QULeRv+ezp2hdKQ+Q9RsHE+o/zuND/skE1MaRS9XrKFKe8OBX/S6FJqh5EJsdLBBs+Q2LwE 3tcN5CEQXNU8HzNwL80wS487E22Lm1XPu6luI7TQkB9HP6+sGZyh0HHjIlOn4M6fKQOHn9vJ2CW o7Au1hkN3J7+dSR13 X-Google-Smtp-Source: AGHT+IGjls3lBddW8jue9cvVaCf9vRvupnJQ9GTSqDJC38TUqs63gYmU+yWxY3XU8XZjabI9hBLEsA== X-Received: by 2002:a05:6214:c88:b0:6e4:9b59:d9ce with SMTP id 6a1803df08f44-6e6ae7c6e0fmr154787516d6.5.1740372562507; Sun, 23 Feb 2025 20:49:22 -0800 (PST) Received: from fauth-a1-smtp.messagingengine.com (fauth-a1-smtp.messagingengine.com. [103.168.172.200]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6e65d779446sm129229726d6.1.2025.02.23.20.49.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 23 Feb 2025 20:49:22 -0800 (PST) Received: from phl-compute-03.internal (phl-compute-03.phl.internal [10.202.2.43]) by mailfauth.phl.internal (Postfix) with ESMTP id A1E7E120006A; Sun, 23 Feb 2025 23:49:21 -0500 (EST) Received: from phl-mailfrontend-01 ([10.202.2.162]) by phl-compute-03.internal (MEProxy); Sun, 23 Feb 2025 23:49:21 -0500 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefvddrtddtgdejjeekgecutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpggftfghnshhusghstghrihgsvgdp uffrtefokffrpgfnqfghnecuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivg hnthhsucdlqddutddtmdenucfjughrpeffhffvvefukfhfgggtuggjsehttdertddttddv necuhfhrohhmpeeuohhquhhnucfhvghnghcuoegsohhquhhnrdhfvghnghesghhmrghilh drtghomheqnecuggftrfgrthhtvghrnhephedugfduffffteeutddvheeuveelvdfhleel ieevtdeguefhgeeuveeiudffiedvnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrg hmpehmrghilhhfrhhomhepsghoqhhunhdomhgvshhmthhprghuthhhphgvrhhsohhnrghl ihhthidqieelvdeghedtieegqddujeejkeehheehvddqsghoqhhunhdrfhgvnhhgpeepgh hmrghilhdrtghomhesfhhigihmvgdrnhgrmhgvpdhnsggprhgtphhtthhopedutddpmhho uggvpehsmhhtphhouhhtpdhrtghpthhtohepohhlihhvvghrrdhsrghnghesihhnthgvlh drtghomhdprhgtphhtthhopehprghulhhmtghksehkvghrnhgvlhdrohhrghdprhgtphht thhopegrnhhkuhhrrdgrrdgrrhhorhgrsehorhgrtghlvgdrtghomhdprhgtphhtthhope hovgdqlhhkpheslhhishhtshdrlhhinhhugidruggvvhdprhgtphhtthhopehlkhhpsehi nhhtvghlrdgtohhmpdhrtghpthhtohepphgvthgvrhiisehinhhfrhgruggvrggurdhorh hgpdhrtghpthhtohepfhhrvgguvghrihgtsehkvghrnhgvlhdrohhrghdprhgtphhtthho pehrtghusehvghgvrhdrkhgvrhhnvghlrdhorhhgpdhrtghpthhtohepjhhovghlrghgnh gvlhhfsehnvhhiughirgdrtghomh X-ME-Proxy: Feedback-ID: iad51458e:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Sun, 23 Feb 2025 23:49:21 -0500 (EST) Date: Sun, 23 Feb 2025 20:49:20 -0800 From: Boqun Feng To: Oliver Sang Cc: "Paul E. McKenney" , Ankur Arora , oe-lkp@lists.linux.dev, lkp@intel.com, Peter Zijlstra , Frederic Weisbecker , rcu@vger.kernel.org, Joel Fernandes Subject: Re: [PATCH v2 2/2] rcutorture: Update ->extendables check for lazy preemption Message-ID: References: <20250224044310.14373-1-boqun.feng@gmail.com> <20250224044310.14373-2-boqun.feng@gmail.com> Precedence: bulk X-Mailing-List: oe-lkp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250224044310.14373-2-boqun.feng@gmail.com> [Cc Joel] On Sun, Feb 23, 2025 at 08:43:10PM -0800, Boqun Feng wrote: > The rcutorture_one_extend_check() function's second last check assumes > that "preempt_count() & PREEMPT_MASK" is non-zero only if > RCUTORTURE_RDR_PREEMPT or RCUTORTURE_RDR_SCHED bit is set. > > This works for preemptible RCU and for non-preemptible RCU running in > a non-preemptible kernel. But it fails for non-preemptible RCU running > in a preemptible kernel because then rcu_read_lock() is just > preempt_disable(), which increases preempt count. > > This commit therefore adjusts this check to take into account the case > fo non-preemptible RCU running in a preemptible kernel. > > Signed-off-by: Boqun Feng > --- > kernel/rcu/rcutorture.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c > index 280bff706017..4cae119dece8 100644 > --- a/kernel/rcu/rcutorture.c > +++ b/kernel/rcu/rcutorture.c > @@ -1901,8 +1901,16 @@ static void rcutorture_one_extend_check(char *s, int curstate, int new, int old, > WARN_ONCE(cur_ops->extendables && > !(curstate & (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH)) && > (preempt_count() & SOFTIRQ_MASK), ROEC_ARGS); > - WARN_ONCE(cur_ops->extendables && > - !(curstate & (RCUTORTURE_RDR_PREEMPT | RCUTORTURE_RDR_SCHED)) && > + > + /* > + * non-preemptible RCU in a preemptible kernel uses preempt_disable() > + * as rcu_read_lock(). > + */ > + mask = RCUTORTURE_RDR_PREEMPT | RCUTORTURE_RDR_SCHED; > + if (!IS_ENABLED(CONFIG_PREEMPT_RCU)) > + mask |= RCUTORTURE_RDR_RCU_1 | RCUTORTURE_RDR_RCU_2; > + > + WARN_ONCE(cur_ops->extendables && !(curstate & mask) && > (preempt_count() & PREEMPT_MASK), ROEC_ARGS); > > /* > -- > 2.39.5 (Apple Git-154) > >