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 C276A22A801; Fri, 11 Jul 2025 23:58:57 +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=1752278339; cv=none; b=sEJV49lXX7QU0v7UORBwI7QrxA8VmjW6wgnCXHa0NDZZlua34n/n4MX40ubNrxqvbwIhhhJnXINGXUUTiQR5w5MdRwGhqCgJjJKCAzwOZPLDIUZRC0exosz7i9CFP/KkUSB/jlq7RkP9ozDcFP73ws4yFZzOM7JJChYCGhe5DT4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752278339; c=relaxed/simple; bh=/5hS7jwAB0F42rvVLLlXskkWnYfakJs6Bk5EEuedoho=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=epzzDdgPuqPVp/fxQ7A+QzNfL0iWMh4J0xEMF0GN1offOqs4Qul5QiJaypMjC+F2NODcaD9oEKUIOr0aJBfm28IqZchorSOhmKMyJQ2f37b3sjpARf2eykrMJ2/bQrwUG8RSNmhtLHpuGzChfZNVK/VKB3aN75T90PTu3LWudH8= 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=FDGJe12W; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=W7kso2If; 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="FDGJe12W"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="W7kso2If" Date: Sat, 12 Jul 2025 01:58:54 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1752278335; 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=imT5HqEkRSNprP7W6NEIrAdL8HwowAu3v+5Es6PMFwM=; b=FDGJe12WV9YV6S3fOxMQ+q4kz9C+xvc9/5227EAJ793/L4hXgNzPtri4QIAKKLFHbVO8RT uW6B9B05weML4Vz4LU0D3IjvnvYmFpD7BweyRpEGBbQ9ASPi38tPIZusebyM26b1dUzau4 brQSyBwmjYDNOqfrE7eYeeRvMSFs0YxpAdHh7rppoY71nJXYqDfhFObtnbtqP+L1kY93jf 9b4OokjKzeM1KDIhVuehERYguwk4E9xu5Psh1sE/ZOuOXxSnvKRyDADdOWnov36ibGbqLX xzn5096FQq7D3q30RjJ35gwY0pWI/19ITsKGatekP02CfRQeVtTXKYlkG2sDow== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1752278335; 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=imT5HqEkRSNprP7W6NEIrAdL8HwowAu3v+5Es6PMFwM=; b=W7kso2IfTKsUrGr4a0eZJAEAENj+pddcsr3DyvSVsWDnogvCKgOeudCbk4HPfVsHOG/80i 4W9bLePA2Sc7K1AA== From: Nam Cao To: Linus Torvalds Cc: Jakub Kicinski , Frederic Weisbecker , Valentin Schneider , Christian Brauner , Thomas Zimmermann , Simona Vetter , Dave Airlie , davem@davemloft.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, pabeni@redhat.com, dri-devel Subject: Re: [GIT PULL] Networking for v6.16-rc6 (follow up) Message-ID: <20250711235854.c7rIj1Ix@linutronix.de> References: <20250711114642.2664f28a@kernel.org> <20250711125349.0ccc4ac0@kernel.org> 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: On Fri, Jul 11, 2025 at 03:19:00PM -0700, Linus Torvalds wrote: > On Fri, 11 Jul 2025 at 14:46, Linus Torvalds > wrote: > > > > I've only tested the previous commit being good twice now, but I'll go > > back to the head of tree and try a revert to verify that this is > > really it. Because maybe it's the now Nth time I found something that > > hides the problem, not the real issue. > > > > Fingers crossed that this very timing-dependent odd problem really did > > bisect right finally, after many false starts. > > Ok, verified. Finally. > > I've rebooted this machine five times now with the revert in place, > and now that I know to recognize all the subtler signs of breakage, > I'm pretty sure I finally got the right culprit. > > Sometimes the breakage is literally just something like "it takes an > extra ten or fifteen seconds to start up some app" and then everything > ends up working, which is why it was so easy to overlook, and why my > other bisection attempts were such abject failures. > > But that last bisection when I was more careful and knew what to look > for ended up laser-guided to that thing. > > And apologies to the drm and netlink people who I initially blamed > just because there were unrelated bugs that just got merged in the > timeframe when I started noticing oddities. You may have had your own > bugs, but you were blameless on this issue that I basically spent the > last day on (I'd say "wasted" the last day on, but right now I feel > good about finding it, so I guess it wasn't wasted time after all). > > Anyway, I think reverting that commit 8c44dac8add7 ("eventpoll: Fix > priority inversion problem") is the right thing for 6.16, and > hopefully Nam Cao & co can figure out what went wrong and we'll > revisit this in the future. Yes, please revert it. I had another person reported to me earlier today about a breakage. We also think that reverting this commit for 6.16 is the right thing. Sorry for causing trouble. Strangely my laptop has been running with this commit for ~6 weeks now without any trouble. Maybe I shouldn't have touched this lockless business in the first place. Best regards, Nam