From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from brightrain.aerifal.cx (brightrain.aerifal.cx [104.156.224.86]) (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 679B92F7AAB for ; Thu, 26 Mar 2026 22:23:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=104.156.224.86 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774563819; cv=none; b=Kp3ziwb1BD4vy2DsZ+oXKpSHK/t+BPSjlLL+jR8ul5Wk2JWOfyvS2kmCI9R9Lq+Ov0fKyTFuFPJZaz92Iq5zHq7lNbL9XiX/2AypVwn3h6Ld4usPxZJqTHcIyPBfxc6Cxubmo1zi3EhwIhf830yKmleiBDDdpgU6Hz7pMMlDIYE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774563819; c=relaxed/simple; bh=eJXRjNKnWrydgGqCNHHSj4x1MJQi4VY5BfYYaYxwSVU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=CaKcEqiL0kLAKD5aiiE5y5fa106p9mtBk9HJpqGycc/ViKiffYoGGe1JtQgChbaAiuIPoZZOt8OotsvmpFZ3ajjzU9w0n9sghUGIXadQ4evmLPrtNASPOJ0eBRk/G/GpUSyadWtFaXcSXwJiXRzKfnlkdPiewV/jnr3Ie66/Brs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=aerifal.cx; spf=pass smtp.mailfrom=aerifal.cx; arc=none smtp.client-ip=104.156.224.86 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=aerifal.cx Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=aerifal.cx Date: Thu, 26 Mar 2026 18:08:15 -0400 From: Rich Felker To: Thomas Gleixner Cc: LKML , Mathieu Desnoyers , =?utf-8?B?QW5kcsOp?= Almeida , Sebastian Andrzej Siewior , Carlos O'Donell , Peter Zijlstra , Florian Weimer , Torvald Riegel , Darren Hart , Ingo Molnar , Davidlohr Bueso , Arnd Bergmann , "Liam R . Howlett" , Uros Bizjak , Thomas =?utf-8?Q?Wei=C3=9Fschuh?= Subject: Re: [patch v2 00/11] futex: Address the robust futex unlock race for real Message-ID: <20260326220815.GE18807@brightrain.aerifal.cx> References: <20260319225224.853416463@kernel.org> <87bjgackw7.ffs@tglx> 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: <87bjgackw7.ffs@tglx> User-Agent: Mutt/1.9.5 (2018-04-13) On Thu, Mar 26, 2026 at 10:59:20PM +0100, Thomas Gleixner wrote: > On Fri, Mar 20 2026 at 00:24, Thomas Gleixner wrote: > > If the functionality itself is agreed on we only need to agree on the names > > and signatures of the functions exposed through the VDSO before we set them > > in stone. That will hopefully not take another 15 years :) > > Have the libc folks any further opinion on the syscall and the vDSO part > before I prepare v3? This whole conversation has been way too much for me to keep up with, so I'm not sure where it's at right now. >From musl's perspective, the way we make robust mutex unlocking safe right now is by inhibiting munmap/mremap/MAP_FIXED and pthread_mutex_destroy while there are any in-flight robust unlocks. It will be nice to be able to conditionally stop doing that if vdso is available, but I can't see using a fallback that requires a syscall, as that would just be a lot more expensive than what we're doing right now and still not work on older kernels. So I think the only part we're interested in is the fully-userspace approach in vdso. If it sounds like I have a misconception of the current state of this proposal from what I said above, let me know and I'll try to figure out what I'm missing and catch up. Rich