From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) (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 31463226D18; Thu, 28 Aug 2025 14:34:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.17 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756391659; cv=none; b=GCPbNhsIqsVKX5uNm+QDBrFTnnJINV4oiSMyAG1+MT4eHbm5RsdynGmrmikVyYavIXoM4YsTV8NtMzN/SrjJetemC9/ZWTUpV4bjE0JrVyKnAEMDsHCm5CslHVfivmMiMU4p7tauvNlMqwpTZR7Nyjcg3e1wCfJT/Yg1LkFzlRM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756391659; c=relaxed/simple; bh=AugeI6+ziOCwr9Df6fzxmSacZoIPicP3QCTXwXZuWAM=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=oDJ+Ifrh1DIAgSIKpDIHNOP0+QJfJekLhUj7Tuk5+pWRFXJRhLAW7Rk+EwBLgcqGkOuBKjuWxI4GKi7gJ1uejLtD0E71fBcocre1G+eFwRdafZcdg1c5XyxgE2FGq/akgHF9Vg+rBdbmLdHLsM3uHvRybAtnEMDllZZPBQL/rMU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org; spf=pass smtp.mailfrom=goodmis.org; arc=none smtp.client-ip=216.40.44.17 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Received: from omf06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 9D38357855; Thu, 28 Aug 2025 14:34:15 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf06.hostedemail.com (Postfix) with ESMTPA id 944D32000E; Thu, 28 Aug 2025 14:34:13 +0000 (UTC) Date: Thu, 28 Aug 2025 10:34:33 -0400 From: Steven Rostedt To: Menglong Dong Cc: Masami Hiramatsu , oe-lkp@lists.linux.dev, kernel test robot , lkp@intel.com, Menglong Dong , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: [linux-next:master] [tracing] dfe0d675df: WARNING:suspicious_RCU_usage Message-ID: <20250828103433.1498f8a7@gandalf.local.home> In-Reply-To: References: <202508281655.54c87330-lkp@intel.com> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: ahbtabrr5y9y7eoyyyxjjhgzdeie95as X-Rspamd-Server: rspamout05 X-Rspamd-Queue-Id: 944D32000E X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX18M9Z1qc+/JGkwBdv/P8HI02lfqXlwoh3o= X-HE-Tag: 1756391653-237669 X-HE-Meta: U2FsdGVkX18Z08jeiwfzhl9wzzBjpYaCscixD6Ujj0Usn5sSYw8XS70FdLMq/6cqP198xPLmk3tsGA4BKBs8VmoOHnOXB4N2/82x7B7bRzRMINtPVXeZdcNhtRVdT8kRmMq3Dl95Qe7e7g/Z+eQ58E8w+HnzH1utgUzrtZXj0D6m+T0WV1mDVrjEYH4b/+CoE7LdLpT4IofYPI1kKOazQgwMPTLRIVuNl++kQ6/qH8ja6xzHxNpq5qQDKJLmcQvkRsaxfjEI8b9ZFTzLFsGCYMgO9//ac2sPG/AHsk316xr0HQ0ogAb8RW4Hg8AIIk/KzoW0QB78cglbHgnqD2oQQdkY8xXOCebV On Thu, 28 Aug 2025 17:09:35 +0800 Menglong Dong wrote: > > [ 354.955971][ T4652] dump_stack_lvl+0x7c/0x90 > > [ 354.955978][ T4652] lockdep_rcu_suspicious+0x14f/0x1c0 > > [ 354.955987][ T4652] __rhashtable_lookup+0x1e0/0x260 > > rcu_read_lock() is not needed in fprobe_entry, but > rcu_dereference_check() is used in rhltable_lookup(), which > causes this warning. Why is rcu_read_lock() not needed in fprobe_entry()? -- Steve > > Adding rcu_read_lock() here is able to suppress this warning. > Maybe we need only rcu_lock_acquire(&rcu_lock_map) here, > but it's not a common usage. What do you think, Masami?