From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 EA6AB246783; Fri, 9 Oct 2026 15:52:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791561165; cv=none; b=n8HsYHEkaZovRap78g6MrkUxY93zqRjkJSEbKVZOw3SQ9/Qk+Z2/tthjhk3RKNrtDbquWApgOKPzNGEoQcoDqAw8vcsfp/nYXuZ9aR2PhtoyDc4tXLXnuWQdJw4FnsNmZv38gnoODsU3ntjcNe/keCKBY1dkXwA40Vvltzj5qMU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791561165; c=relaxed/simple; bh=+632BxfAIPKPTC4nLf/PZ9on1zah9Og/rWyomBJqmRI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ML7OOUv1aHLiReic4wWdeaClQU2lUoHBtwF/R29ffZ4y/A361HZbJUFAmWPYadbjM2adapQ4i1+gsZz1YtIyBt3ybH1W0mtaItR2bEGqiUKdj/0MEyS49AQd2zU9JH36eW2o3Vsd/GwnM7R/gq0exBf5u7D5mVXGbAUZg+WEJTU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KHDMwhBw; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="KHDMwhBw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 848AD1F00893; Fri, 9 Oct 2026 15:52:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791561164; bh=0DXjYMvRmEg6F57An+CASAoisofDrEv/t1VR5wLbgNM=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To; b=KHDMwhBwPbggKTF8TXjDAZxIfe8YpIevivj37SAKBd5qpesQeolLpZOtNZfk8rcLB 1RA14HatE9GfBdKrFzYqi73t3N6QSY+kudDXEado/f8LqDqKTBktISyWU+RkXJk6F5 o4DCpcNVdtpc3Vczmb70fmBkMXdYH7ITJ54yVsLSgqjMMvRTaMfA2dWtL3tW7dEz78 QAPVZKzNGYE1w/jkyzuqmGXRyU5Dyl50CT3LjCADdr43NygFUUdUYR3iPs2t+59tLR i/WXvDUORW0aNok2clYBGybCtx+RNxJLI2mjaE2Q+5hHS+e9m94QJVaSDwJv+l60rw RO9k/xL1i5HXQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 5C2F0CE0B28; Fri, 9 Oct 2026 08:52:44 -0700 (PDT) Date: Fri, 9 Oct 2026 08:52:44 -0700 From: "Paul E. McKenney" To: "Lorenzo Stoakes (ARM)" Cc: Kees Cook , Nathan Chancellor , Nicolas Schier , Manuel Ebner , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH v1 1/2] kbuild: Mark the kernel image gzip recipes as recursive Message-ID: Reply-To: paulmck@kernel.org References: <20261009062722.i.253-kees@kernel.org> <20261009062733.3119731-1-kees@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, Oct 09, 2026 at 01:05:00PM +0100, Lorenzo Stoakes (ARM) wrote: > On Thu, Oct 08, 2026 at 11:27:30PM -0700, Kees Cook wrote: > > Since commit 48ebe1cbbeb51 ("kbuild: compress the kernel with pigz if > > available"), cmd_gzip runs pigz through scripts/jobserver-exec, which > > takes the job slots make has free. GNU Make passes the jobserver pipe > > only to recipes it treats as recursive, but leaves --jobserver-auth in > > MAKEFLAGS for all of them. The make 4.3 in CentOS Stream 9 also hides > > the pipe in sub-makes (a backport of the fix for GNU Make bug 58232), so > > jobserver-exec cannot open it, runs pigz on one thread, and prints: > > > > WARNING: Unable to reopen jobserver read-side pipe: FileNotFoundError(2, 'No such file or directory') > > > > Mark the gzip recipes as recursive with "+", as commit ecab4115c44cc > > ("kbuild: mark `rustc` (and others) invocations as recursive") did for > > rustc. As with those, "make -n" now runs them. > > > > Tested ARCH=x86_64 and ARCH=arm64 defconfig with GNU Make 4.3 plus > > CentOS Stream 9's make-4.3-cloexec.patch, GCC 16.2.0, and -j64: without > > this change the warning appears and pigz runs with "-p 1"; with it there > > is no warning, and pigz runs with "-p 54" and "-p 64". > > > > Reported-by: Paul E. McKenney > > Closes: https://lore.kernel.org/all/0ddb5e5e-f801-444c-aa98-0cfe814a3026@paulmck-laptop/ > > Fixes: 48ebe1cbbeb51 ("kbuild: compress the kernel with pigz if available") > > Assisted-by: LLM > > Signed-off-by: Kees Cook > > Nice find! > > Acked-by: Lorenzo Stoakes (ARM) > > Sorry for breaking your build Paul ;) Hey, this was the fastest bisection that I have ever done by far! Normally it takes hours per step, but this was about 40 seconds per step. ;-) Thanx, Paul