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[209.85.128.48]) by smtp.gmail.com with ESMTPSA id l25-20020a1709066b9900b009894b476310sm3824495ejr.163.2023.07.08.12.23.10 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 08 Jul 2023 12:23:10 -0700 (PDT) Received: by mail-wm1-f48.google.com with SMTP id 5b1f17b1804b1-3fbf1b82dc7so33673945e9.2 for ; Sat, 08 Jul 2023 12:23:10 -0700 (PDT) X-Received: by 2002:a5d:684c:0:b0:314:4915:689 with SMTP id o12-20020a5d684c000000b0031449150689mr7611320wrw.34.1688844189725; Sat, 08 Jul 2023 12:23:09 -0700 (PDT) MIME-Version: 1.0 References: <5c7455db-4ed8-b54f-e2d5-d2811908123d@leemhuis.info> <2023070359-evasive-regroup-f3b8@gregkh> <2023070453-plod-swipe-cfbf@gregkh> <20230704091808.aa2ed3c11a5351d9bf217ac9@linux-foundation.org> <2023070509-undertow-pulverize-5adc@gregkh> <7668c45a-70b1-dc2f-d0f5-c0e76ec17145@leemhuis.info> <20230705084906.22eee41e6e72da588fce5a48@linux-foundation.org> <20230708103936.4f6655cd0d8e8a0478509e25@linux-foundation.org> In-Reply-To: From: Linus Torvalds Date: Sat, 8 Jul 2023 12:22:53 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: Fwd: Memory corruption in multithreaded user space program while calling fork To: Suren Baghdasaryan Cc: Andrew Morton , Thorsten Leemhuis , Bagas Sanjaya , Jacob Young , Laurent Dufour , Linux Kernel Mailing List , Linux Memory Management , Linux PowerPC , Linux ARM , Greg KH , Linux regressions mailing list Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 7D330C0003 X-Rspam-User: X-Stat-Signature: gjgeenaumyifqj1mbhpqoeg6nkrgajzb X-Rspamd-Server: rspam03 X-HE-Tag: 1688844193-400367 X-HE-Meta: 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 R1eWM5E7 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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 Sat, 8 Jul 2023 at 12:17, Suren Baghdasaryan wrote: > > Do you want me to disable per-VMA locks by default as well? No. I seriously believe that if the per-vma locking is so broken that it needs to be disabled in a development kernel, we should just admit failure, and revert it all. And not in a "revert it for a later attempt" kind of way. So it would be a "revert it because it added insurmountable problems that we couldn't figure out" thing that implies *not* trying it again in that form at all, and much soul-searching before somebody decides that they have a more maintainable model for it all. If stable decides that the fixes are not back-portable, and the whole thing needs to be disabled for stable, that's one thing. But if we decide that in mainline, it's a "this was a failure" thing. Linus