From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 B7A5620311 for ; Mon, 14 Jul 2025 10:14:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752488056; cv=none; b=CnxycQY6apHcMgZhFiyE9ua6itRxW9LmzYMiCFnAhcFn2J3huFaEb+akhINL9ZVrznk29SjL3EIOjMpEGr3atjN+Hc3SCCWJGvO+IKe84LShmeCygMuWxjGUxxPCNYar84Xu7xkDReM2wNrhA46vGlcvDGkiY1vIFSqSCPCd/6w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752488056; c=relaxed/simple; bh=cOpEyTSiBLUg150TjbxK79lmnioNTJJemNhL2gS6kZ0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=lEaM5UyaYOsUUPXF2E5NAS/EeDdHLCOcs9tq5yzakfsT2MZ+e3uLvgV23i6Sf8VYMJYnzGFBKTayhtQW0y4m/s+GrIsbqinxAYqy5yOr3gn2t+zdhCzCgL7Rdc4/ZaSfg2dgvIyg0O6OZ9j2b2ZeEdZcZW1CG6HO06kyIFnyfDc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=hR1+mZFQ; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=1CXlaM7n; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="hR1+mZFQ"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="1CXlaM7n" Date: Mon, 14 Jul 2025 12:14:10 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1752488052; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=cOpEyTSiBLUg150TjbxK79lmnioNTJJemNhL2gS6kZ0=; b=hR1+mZFQsXh07BTP0mr4H6/1n2IrQRgS2o0EIL2eytqFrc6ehL8mLh0OTJFWJSGNZcIF1T 8mLPa4aDKRNR1TGEjGTFqJ5EIY/00c8SFW9z39s0i/YC5ZoryvglfDI+AkjtHM2MtKFH/E W2x3jd63FF297o3XQrrpFba1tC+NKbCUC/BbAVy/L/yM8Tb+6xnhFuqoKVSLDkcO8Mk8bh QxOGPigbkoI/sd/FMgA9vZWOXEirlmNwBy7KmvhIYAqr4eswSj1LqQhq+iuTa//gCKz0dx ubA+vRM2hXGL2BrtESUW+f8AX4a2Cog77ZLOLboU/IYZW8zOLnNlHvSg0u1APw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1752488052; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=cOpEyTSiBLUg150TjbxK79lmnioNTJJemNhL2gS6kZ0=; b=1CXlaM7nBkSJCEFlqjOb1kUplpzguYM6FkOGWrXWpL5Jt5rhN4NahG5M83kHFYnUEPfGpQ H3cgbrFzGHNsqRDg== From: Nam Cao To: Christian Brauner Cc: Linus Torvalds , Xi Ruoyao , Frederic Weisbecker , Valentin Schneider , Alexander Viro , Jan Kara , Sebastian Andrzej Siewior , John Ogness , Clark Williams , Steven Rostedt , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, linux-rt-users@vger.kernel.org, Joe Damato , Martin Karsten , Jens Axboe Subject: Re: [PATCH v3] eventpoll: Fix priority inversion problem Message-ID: <20250714101410.Su0CwBrb@linutronix.de> References: <20250710040607.GdzUE7A0@linutronix.de> <6f99476daa23858dc0536ca182038c8e80be53a2.camel@xry111.site> <20250710062127.QnaeZ8c7@linutronix.de> <20250710083236.V8WA6EFF@linutronix.de> <20250711050217.OMtx7Cz6@linutronix.de> <20250711-ermangelung-darmentleerung-394cebde2708@brauner> <20250711095008.lBxtWQh6@linutronix.de> <20250714-leumund-sinnen-44309048c53d@brauner> Precedence: bulk X-Mailing-List: linux-rt-devel@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: <20250714-leumund-sinnen-44309048c53d@brauner> On Mon, Jul 14, 2025 at 10:59:58AM +0200, Christian Brauner wrote: > My lesson from this is that touching epoll without a really really good > and urgent reason always end up a complete mess. So going forward we'll > just be very careful here. And my lesson is that lockless is hard. I still have no clue what is the bug in this patch. I am implementing a new solution now, completely ditching this old approach. It survives some basic testing, and the numbers look promising. I may post it later this week. Nam