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 88D2D190664 for ; Tue, 25 Mar 2025 22:05:53 +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=1742940353; cv=none; b=IrYvQ8gS9muH4xmP07POypT7jKBc3eiptNSbSGZzQWZvJgCBARBjWfv8h/Fz3GVjFoYYrOoP+EeSzuIbfKsNaTbXfmnDP0+24dk7lEa5mour/jho0CFFLFN4wur3kkm2VnMLlQg7vEvpIc7rNTfcjdKKirByO8NzXUA2/KQKXAU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742940353; c=relaxed/simple; bh=H/G0uzHtJbq8O5EuUJeV+sv7t7xBlJqB/VXFBoAMC4M=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=nbKMuqTWuU0UN6Ymy/QcDrS6doNPrxrLP4cItZ4bAb8xorMIIHcI7Ik7AUX7xSrPEphDd0cCAaIXoVKV6FeerH0PtjvL2cFz72WTLp6JzHcgJLIJwuJdXCKaRXgr2s4V5Lo0Ujw4uT58vEooqb21o3JsFZlzV4M+bqypfDsjiCY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=m4NjjxMQ; 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="m4NjjxMQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6F6D2C4CEE4; Tue, 25 Mar 2025 22:05:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1742940353; bh=H/G0uzHtJbq8O5EuUJeV+sv7t7xBlJqB/VXFBoAMC4M=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=m4NjjxMQYlIKmEn1SMB18Y4RyVeA/RS4KMYOPCvZHSnXUIrICOKhLf2NzWJJDguBP u/L8xLbUEPaAJHgmNP2TfDQ+UmdU7HQjr7Tx5r9oXS9sXfmoeVbWeTyR68mg4xjL7k M3HUruK9/YylWNkiVxvHQypiBSXpSgSTETbv/QN9Ozv4P2o6dbYGKY72bFTPPYxLUn /N8fnGSVVEhTT7UeGKqjAirdkSIwz3Unrfx/lZEYYeSX0HAXXfrPhN+KLglOEftflx AoeATdS/cOy+Egx77G466fzxYuIDYOINa2z11s8TUfaBYcFPIBLpo4DpkDuMCZ8ymr 0D9JJKQ190jrg== Date: Tue, 25 Mar 2025 23:05:48 +0100 From: Ingo Molnar To: Nick Terrell Cc: Michael Kelley , Ard Biesheuvel , "dsterba@suse.com" , "brgerst@gmail.com" , "linux-kernel@vger.kernel.org" Subject: Re: Compile problems w/gcc 9.4.0 in linux-next Message-ID: References: <323A7651-9BD8-4C8B-8784-8C9DAEF5FC88@meta.com> <9B7AFB33-E930-44F4-B5AE-1414B3E9A56A@meta.com> 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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <9B7AFB33-E930-44F4-B5AE-1414B3E9A56A@meta.com> * Nick Terrell wrote: > > > > On Mar 25, 2025, at 6:18 AM, Ingo Molnar wrote: > > > > > > > > > * Nick Terrell wrote: > > > >> > >> > >>> On Mar 21, 2025, at 8:16 AM, Michael Kelley wrote: > >>> > >>>> > >>> From: Ingo Molnar Sent: Friday, March 21, 2025 12:38 AM > >>>> > >>>> * Michael Kelley wrote: > >>>> > >>>>>> What are your thoughts as maintainers of lib/zstd? > >>>>> > >>>>> FYI, the same segfault occurs with gcc 10.5. The problem is fixed > >>>>> in gcc 11.4. > >>>> > >>>> So the patch below would work this around on GCC9 and GCC10? > >>> > >>> I've confirmed that the patch gives a clean compile with gcc 9.4. > >>> > >>> Note that I confirmed yesterday that the gcc problem is fixed with > >>> 11.4. I don't know about earlier gcc 11 minor versions. Lemme see > >>> if I can get the original gcc 11 release and try that to confirm that > >>> your patch has the right version cutoff. > >> > >> Thanks for the report & proposed fix! > >> > >> If you can test gcc-11.0, that would be great, otherwise we could just > >> cut off at (__GNUC__ >= 12 || (__GNUC__ == 11 && __GNUC_MINOR__ >= 4)) > >> > >> I am preparing the zstd-v1.5.7 update, and I will pull a patch that > >> fixes this into my tree. If someone wants to submit a patch I'll pull > >> that, otherwise I can submit one later today. > > > > The proper cutoff would be GCC 11.1, not 11.4, as per the testing of > > Michael Kelley, right? > > Sorry, I didn't quite realize that the [tip: x86/core] was a commit. I'll drop > my patch, and just make sure that the fix is preserved in the zstd-v1.5.7 > upgrade. Yeah, the segfault triggered due to changes in the x86 tree, so the fix (workaround) is now upstream, but I think the cutoff is overly conservative: 1400c87e6cac ("zstd: Increase DYNAMIC_BMI2 GCC version cutoff from 4.8 to 11.0 to work around compiler segfault") So it might be a good idea to follow it up with your improved cutoff patch, as a delta patch on top? That doesn't have any urgency that I can see, so it can go through your tree, or any other path you'd prefer! Thanks, Ingo