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t=1677520413; bh=SAJSlQTkp0HhEdWMJDyOk2c0VmbdGe64aI1Pp9sBJTU=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=QAEDF4xsiW5hWShqlorEI9KBJz3MEjCCmdzHJfFEydcpUUEUSD8nb3qeDLXMp6bx3 1FCNvJOGed5N0/hTpdlkrJuFz41GCDAqwO73wyqNNVhoiMc4jlrzG6WhZAuv3JXSk+ aSXzZCHhtH3Fo0lG/jlqz5rMliurJBdLvoY9IrJJdLgFrt1juLZe8j+n1QPABmaqpl K0oKQJ/p7bZqSLBPISzE6CyBrkn+UxXxHFTOMMb4+22DDAq+dyzyJaXinrFUzRnA/u boJHYpfXaKwJIJdVFi/fO0eyAHr6LwecIecymCeCS9qc25z62Sd4pEm0WDKrgFbLhP HfF1bDhIqq1MQ== Received: by mail-lf1-f53.google.com with SMTP id bp25so9717554lfb.0 for ; Mon, 27 Feb 2023 09:53:33 -0800 (PST) X-Gm-Message-State: AO0yUKXsa9AYZbyXKrs8IIQkqOePZ6WQjuIr5lfHZY+aiqyBnMXwKcQ2 adMQjRQtGJtOTwmQSG/H6JEwj9BHAxk9mc0NNOs= X-Google-Smtp-Source: AK7set/YEGwo805dHGA6DYHHdfoMRlSpmYLwmofHWomaxwAmR6Oksv1i9+fHz0SRMAq6j/ROjcH/CTRghgOjewmVzYo= X-Received: by 2002:a19:7606:0:b0:4dc:807a:d143 with SMTP id c6-20020a197606000000b004dc807ad143mr7714348lff.7.1677520411316; Mon, 27 Feb 2023 09:53:31 -0800 (PST) MIME-Version: 1.0 References: <20221227092634.445212-1-liushixin2@huawei.com> <20230129134147.f19ca0641f1133f3e3bc185b@linux-foundation.org> <20230131150644.GA2605@willie-the-truck> <20230131150750.GB2605@willie-the-truck> <20230207112940.GA12147@willie-the-truck> <8c287b1d-476c-7b00-27f6-76c3a1a5fd46@leemhuis.info> <5a05e758-3c26-875a-af3a-6d7c8ddde653@leemhuis.info> In-Reply-To: <5a05e758-3c26-875a-af3a-6d7c8ddde653@leemhuis.info> From: Ard Biesheuvel Date: Mon, 27 Feb 2023 18:53:20 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH RFC] arm64/vmalloc: use module region only for module_alloc() if CONFIG_RANDOMIZE_BASE is set To: Linux regressions mailing list Cc: Liu Shixin , Andrew Morton , Catalin Marinas , Uladzislau Rezki , Christoph Hellwig , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Will Deacon Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 2A2ED180010 X-Stat-Signature: 1o3yb1cks5zaos1dtfkfdkdnbmy1k9yz X-Rspam-User: X-HE-Tag: 1677520416-514547 X-HE-Meta: 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 qjKaOin1 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, 27 Feb 2023 at 18:17, Linux regression tracking (Thorsten Leemhuis) wrote: > > > > On 27.02.23 17:14, Ard Biesheuvel wrote: > > On Mon, 27 Feb 2023 at 16:08, Linux regression tracking (Thorsten > > Leemhuis) wrote: > >> > >> [CCing the regression list, as it should be in the loop for regressions: > >> https://docs.kernel.org/admin-guide/reporting-regressions.html] > >> > >> On 07.02.23 12:29, Will Deacon wrote: > >>> On Tue, Jan 31, 2023 at 05:03:32PM +0100, Ard Biesheuvel wrote: > >>>> On Tue, 31 Jan 2023 at 16:07, Will Deacon wrote: > >>>>> On Tue, Jan 31, 2023 at 03:06:44PM +0000, Will Deacon wrote: > >>>>>> On Sun, Jan 29, 2023 at 01:41:47PM -0800, Andrew Morton wrote: > >>>>>>> On Sun, 29 Jan 2023 10:44:31 +0800 Liu Shixin wrote: > >>>>>>>> On 2022/12/27 17:26, Liu Shixin wrote: > >>>>>>>>> After I add a 10GB pmem device, I got the following error message when > >>>>>>>>> insert module: > >>>>>>>>> > >>>>>>>>> insmod: vmalloc error: size 16384, vm_struct allocation failed, > >>>>>>>>> mode:0xcc0(GFP_KERNEL), nodemask=(null),cpuset=/,mems_allowed=0 > >>>>>>>>> > >>>>>>>>> If CONFIG_RANDOMIZE_BASE is set, the module region can be located in the > >>>>>>>>> vmalloc region entirely. Although module_alloc() can fall back to a 2GB > >>>>>>>>> window if ARM64_MODULE_PLTS is set, the module region is still easily > >>>>>>>>> exhausted because the module region is located at bottom of vmalloc region > >>>>>>>>> and the vmalloc region is allocated from bottom to top. > >>>>>>>>> > >>>>>>>>> Skip module region if not calling from module_alloc(). > >>>>>>> > >>>>>>> I'll assume this is for the arm tree. > >>>>>>> > >>>>>>> Acked-by: Andrew Morton > >>>>>> > >>>>>> This looks like the same issue previously reported at: > >>>>>> > >>>>>> https://lore.kernel.org/all/e6a804de-a5f7-c551-ffba-e09d04e438fc@hisilicon.com/ > >>>>>> > >>>>>> where Ard had a few suggestions but, afaict, they didn't help. > >>>>>> > >>>> > >>>> Thanks for the cc. > >>>> > >>>> So this is a bit clunky, and I wonder whether we wouldn't be better > >>>> off just splitting the vmalloc region into two separate regions: one > >>>> for the kernel and modules, and one for everything else. That way, we > >>>> lose one bit of entropy in the randomized placement, but the default > >>>> 48-bit VA space is vast anway, and even on 39-bit VA configs (such as > >>>> Android), I seriously doubt that we come anywhere close to exhausting > >>>> the vmalloc space today. > >>> > >>> That sounds like a good idea to me. > >>> > >>> Liu Shixin -- do you think you could have a go at implementing Ard's > >>> suggestion instead? > >> > >> Liu Shixin, did you ever look into realizing this idea? > >> > >> Or was some progress already made and I just missed it? > > > > This patch > > > > https://lore.kernel.org/all/20230223204101.1500373-1-ardb@kernel.org/ > > > > should fix the issue. > > Great, many thx. > > >> I'm asking, as the idea discussed afaics is not only supposed to fix the > >> regression you tried to address, but also one that is now three months > >> old and stalled since Mid-December -- which is really unfortunate, as > >> that's not how regressions should be handled. :-/ > > > > Is it documented anywhere how regressions should be handled? > > https://docs.kernel.org/process/handling-regressions.html > > Side note: that also mentions use of the "Link" tag. If the patch had > one, I'd noticed it and wouldn't bothered anyone here. > Thanks for the reference. I wasn't aware that that document existed. However, please be careful with calling everything a regression: in this particular case, the 10G pmem device simply never worked in this configuration, and so calling this a regression, and quoting all these rules that we must now abide by is, quite frankly, not entirely appropriate. Can we please reserve the 'regression' label for cases where the workflow of a real user stopped working after a kernel change? I agree that this must never happen, and so we should prioritize those cases over the ones that are just ordinary bugs and not regressions. > > The > > mailing list is flooded with hard to reproduce reports from users as > > well as automatic fuzzers and build bots, so I don't think it is > > entirely unreasonable to move unresponsive reporters to the back of > > the queue. > > I do that sometimes, but fwiw, from what I can see it wasn't a reporter > that was unresponsive: > > https://lore.kernel.org/linux-arm-kernel/c1ff5cae-7f56-7fdb-c832-ffbcc177535b@leemhuis.info/ > > But I might be missing something, sorry if I do. And there was the > festive season what complicated everything. Whatever, as long as this > this is fixed. > > /me wonders if we should ask "chenxiang (M)" to test that patch, too; > but /me is not even totally sure it's the same problem > Yes, to me it looks like exactly the same issue. > >> But well, it afaik was > >> caused by a patch from Ard, so it's obviously not your job to address > >> it. But it seems you were working on it. > > > > We are all working together here, so please refrain from telling > > people what they should or should not be working on. (I am aware that > > you probably did not mean it that way, but things tend to get lost in > > translation very easily on the mailing list) > > Maybe I found the wrong words, sorry. > No worries. Your work is much appreciated, as I am sure it's a thankless job at times. Thanks, Ard.