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 1ADE32FFDEC; Tue, 18 Nov 2025 13:05:07 +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=1763471107; cv=none; b=u3KBzeUhVuQxp5Nsd1uiUs+wh3Qvw2byAk8kjGhvZhNtkA9SfTv7Rc6bwwP69FN7RF5TztRTRJArFuDW8kdQywFhXajRjdl5p/a9jUX6mUh5XemaiYd8ZkcuydNAVSP6upJ5uo29dKQTzVILdjjIDA7wWcpk2xLw7GZJY8L8XJw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763471107; c=relaxed/simple; bh=VKX8ltzch9Q5vZ1SWMb61T9KplseCWx1MK4WpjDisR8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=sFFZ0Ie+vZ7QQLOEVFSoxqJF5Y4Byqm+TBquii1DeQR2ivYs+Aoi1nIailwLvTOVV2jWk869A3vvwb7sMEuIild2c6T5UUsvk3oJPScfbnp662xNKuQa2S15YbqkkofBfby4tMK/Fcgcc6KTCx3ncHwcd7hnwdZShK0ZCdEufsw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=B9IZiJSd; 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="B9IZiJSd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5BDE2C4CEF5; Tue, 18 Nov 2025 13:05:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763471106; bh=VKX8ltzch9Q5vZ1SWMb61T9KplseCWx1MK4WpjDisR8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=B9IZiJSde4vWexhGKkOxOLtTfI+3hb9b0yfsxZAaeviomAT+VbLuCz8malOXBxJ8h Akd3Ernkt23PanuJXSfq+ynZY7hViKzBhBK19QUvTZZmnx8URiAflMIsRY+COUMRe8 kxnjNs6CX0XhI+0+I6HXPIsaKVMzUTk3i4A+3P2yPbPkQyD7PfbJoe/F13NJYfhomX qx/NMjdHBTmjms4uiE8FJvuL7JvgRHHJm5LCLQyOcOU/iC3jgNjPIbK8aHamDFSssV 9IbqifOOp/8yMySexxOoesO8QHureQN7moYrJDLfMGxlkYZrvNeDL6+FsnPjzzTv2r 6M1XoXzeDs+GA== Date: Tue, 18 Nov 2025 14:05:03 +0100 From: Frederic Weisbecker To: "Paul E. McKenney" Cc: Steven Rostedt , Stephen Rothwell , Neeraj Upadhyay , Boqun Feng , Uladzislau Rezki , Masami Hiramatsu , Linux Kernel Mailing List , Linux Next Mailing List , Sebastian Andrzej Siewior Subject: Re: linux-next: manual merge of the rcu tree with the ftrace tree Message-ID: References: <20251114135226.64831207@canb.auug.org.au> <20251114074255.3e535084@gandalf.local.home> <054ceff1-87b7-4729-8589-b7dd22887bc1@paulmck-laptop> 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=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <054ceff1-87b7-4729-8589-b7dd22887bc1@paulmck-laptop> Le Fri, Nov 14, 2025 at 09:06:29AM -0800, Paul E. McKenney a écrit : > On Fri, Nov 14, 2025 at 03:48:52PM +0100, Frederic Weisbecker wrote: > > Le Fri, Nov 14, 2025 at 07:42:55AM -0500, Steven Rostedt a écrit : > > > On Fri, 14 Nov 2025 13:52:26 +1100 > > > Stephen Rothwell wrote: > > > > > > > Hi all, > > > > > > > > Today's linux-next merge of the rcu tree got a conflict in: > > > > > > > > kernel/trace/trace_syscalls.c > > > > > > > > between commit: > > > > > > > > a544d9a66bdf ("tracing: Have syscall trace events read user space string") > > > > > > > > from the ftrace tree and commit: > > > > > > > > 35587dbc58dd ("tracing: Guard __DECLARE_TRACE() use of __DO_TRACE_CALL() with SRCU-fast") > > > > > > > > from the rcu tree. > > > > > > > > I fixed it up (Maybe - see below) and can carry the fix as necessary. This > > > > is now fixed as far as linux-next is concerned, but any non trivial > > > > conflicts should be mentioned to your upstream maintainer when your tree > > > > is submitted for merging. You may also want to consider cooperating > > > > with the maintainer of the conflicting tree to minimise any particularly > > > > complex conflicts. > > > > > > Thanks for the update. > > > > > > > > > > > > > > diff --cc kernel/trace/trace_syscalls.c > > > > index e96d0063cbcf,3f699b198c56..000000000000 > > > > --- a/kernel/trace/trace_syscalls.c > > > > +++ b/kernel/trace/trace_syscalls.c > > > > @@@ -878,6 -322,8 +890,7 @@@ static void ftrace_syscall_enter(void * > > > > * buffer and per-cpu data require preemption to be disabled. > > > > */ > > > > might_fault(); > > > > + preempt_rt_guard(); > > > > - guard(preempt_notrace)(); > > > > > > My code made it so that preemption is not needed here but is moved later > > > down for the logic that does the reading of user space data. > > > > > > Note, it must have preemption disabled for all configs (including RT). > > > Otherwise, the data it has can get corrupted. > > > > > > Paul, can you change it so that you *do not* touch this file? > > > > Ok, I've zapped the commit for now until we sort this out. > > Thank you, Frederic, and I guess putting this in -next did indeed find > some problems, so that is good? ;-) Indeed, mission accomplished ;-) Steve proposed here to actually restore the patch: https://lore.kernel.org/lkml/20251114110136.3d36deca@gandalf.local.home/ But later said the reverse: https://lore.kernel.org/lkml/20251114121141.5e40428d@gandalf.local.home/ So for now I'm still keeping it outside -next. I hope it is not a necessary change in your srcu series? Thanks. -- Frederic Weisbecker SUSE Labs