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([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id k9-20020a170902760900b001b54a88e6adsm7515466pll.309.2023.06.28.06.01.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 28 Jun 2023 06:01:48 -0700 (PDT) Sender: Guenter Roeck Message-ID: Date: Wed, 28 Jun 2023 06:01:47 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Content-Language: en-US From: Guenter Roeck To: Linus Torvalds , Dinh Nguyen , "Paul E. McKenney" , Shuah Khan Cc: linux-kernel@vger.kernel.org, vishal.moola@gmail.com, akpm@linux-foundation.org, sfr@canb.auug.org.au References: <20230627221430.464073-1-dinguyen@kernel.org> Subject: Re: [PATCH] Revert "nios2: Convert __pte_free_tlb() to use ptdescs" In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/27/23 16:23, Guenter Roeck wrote: > On 6/27/23 15:35, Linus Torvalds wrote: >> On Tue, 27 Jun 2023 at 15:14, Dinh Nguyen wrote: >>> >>> This reverts commit 6ebe94baa2b9ddf3ccbb7f94df6ab26234532734. >>> >>> The patch "nios2: Convert __pte_free_tlb() to use ptdescs" was supposed >>> to go together with a patchset that Vishal Moola had planned taking it >>> through the mm tree. By just having this patch, all NIOS2 builds are >>> broken. >> >> This is now at least the third time just this merge window where some >> base tree was broken, and people thought that linux-next is some kind >> of testing ground for it all. >> >> NO! >> >> Linux-next is indeed for testing, and for finding situations where >> there are interactions between different trees. >> >> But linux-next is *not* a replacement for "this tree has to work on >> its own". THAT testing needs to be done independently, and *before* a >> tree hits linux-next. >> >> It is *NOT* ok to say "this will work in combination with that other >> tree". EVERY SINGLE TREE needs to work on its own, because otherwise >> you cannot bisect the end result sanely. >> >> We apparently had the NIOS2 tree being broken. And the RCU tree was >> broken. And the KUnit tree was broken. >> > > Actually, this one is broken in linux-next as well because it was pulled > into it, but the context patches needed to make it work (compile) are not > there. It is also broken in next/pending-fixes for the same reason. > > Only this happened so quick that by the time I noticed and reported > and argued that, no, I did not try to apply this patch on its own, > the pull request into mainline was already sent and applied. > > Problem with linux-next is that it is so badly broken that it would take > a full-time position to track down all its failures. Then there are those > last-minute patches added in the week (or days) before the commit window > opens which break it again. This is one example, but there is at least > one more in linux-next (and pending-fixes); see > https://kerneltests.org/builders/next-sh-pending-fixes/builds/822/steps/buildcommand/logs/stdio > And now the broken (never compiled) patch made it into mainline and breaks the sh:dreamcast_defconfig build there. Yes, it does happen a lot that builds are temporarily broken in mainline because patch series are split up among maintainers and submitted to mainline without regard of buildability. I have learned to live with that and don't normally report it because I know (ok, hope) it is going to be fixed by the end of the commit window. I personally find patch series - typically doing some cleanup - which are not even build tested on the affected architectures much more annoying. Guenter