From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 B06FC224F0 for ; Mon, 4 Nov 2024 18:08:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730743687; cv=none; b=YzLGNmauz4+jPQlFCiLwmon40thB53Ps1mdzg6j6ZeD21MP0lakD3UpNgbaZNgVAZOorjUckMKHqq1LkdBrjSMK6AKgJMu/ufgAaRJxcpPxZkvyobNv9vXx4wnWFWWNAa0pvNNSlxoIobEc+O3PfeF11/dje9LdFJz9jedi1k2M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730743687; c=relaxed/simple; bh=PVnrBL4lkjktcJ+d1zuTLRbNSKpea3enMqS82gtgDdE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=LwEEiEGfSzbohV2y42yJRqNG+mR6tYE3TmXDwctxBu89FlWpjQlXJ2o+Po4f2C9Jpj9yJNh75ldXqVb3inOnjXY3r+2pB4irFK4iPpnQLYQA3TNUIyuQB3PRvN8di9tuSGhATrT6TSV0uhl5VJEBnVaFcIkqJO/ba+jtqrh+Dh4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=H+nlp8nv; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="H+nlp8nv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0AAD6C4CECE; Mon, 4 Nov 2024 18:08:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730743687; bh=PVnrBL4lkjktcJ+d1zuTLRbNSKpea3enMqS82gtgDdE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=H+nlp8nvIcoB9P8nky4+5VamsTcU4SmIHwVifd91p4+CczWtgx0IsmfnAaffaBNeT 0bXVUC+fscyYmMFkq2WNRw25f/ZWDjTbiIwWTz430egNEVX4QYGET+qyNQ3djupsDU 2wqVtftsnY50wlo4Fg522CphKNonZ69nJQExRk9dAD79E8yYbvjqXdHp8gtuzxSnra wEQ4Gd30Gx6Lblv3wIvbqaONfJIUmJPJeYxDWGWqJBDAAafqIobQmZ5/6vbdYy9OMI PvD7xhub+4qJjOHN3a5gywN3aYcL4B8tf2rXfSQj1vNDUepBtETTiwkYCYKcxBykZp FyWEnpFmbPqzA== Date: Mon, 4 Nov 2024 08:08:05 -1000 From: Tejun Heo To: Boqun Feng Cc: Hillf Danton , Sebastian Andrzej Siewior , "Paul E. McKenney" , Marco Elver , linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org Subject: Re: [BUG] -next lockdep invalid wait context Message-ID: References: <41619255-cdc2-4573-a360-7794fc3614f7@paulmck-laptop> <66a745bb-d381-471c-aeee-3800a504f87d@paulmck-laptop> <20241102001224.2789-1-hdanton@sina.com> 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-Disposition: inline In-Reply-To: Hello, On Fri, Nov 01, 2024 at 05:45:01PM -0700, Boqun Feng wrote: ... > Because it's a different bug. > > schedule(): > __schedule(): > rq_lock(); // <- rq lock is a raw spin lock, so no sleep inside > switch_mm_irqs_off(): > trace_tlb_flush(): > bpf_trace_run2(): > stack_map_get_build_id_offset(): > mmap_read_trylock(): // this is actually ok, because > // trylock() on rwsem won't > // sleep. > __mmap_lock_trace_acquire_returned(): > get_mm_memcg_path(): > cgroup_path(): > kernfs_path_from_node(): > read_lock_irqsave(); // on RT, read_lock() > // is a rwsem IIUC, > // so might sleep. > // hence the issue. > > Maybe kernfs can use RCU instead of read_lock here? I don't know... Yeah, we should be able to make kn->name RCU protected and drop the usage of the rename lock in read paths. Thanks. -- tejun