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Sat, 08 Jul 2023 12:42:12 -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: Suren Baghdasaryan Date: Sat, 8 Jul 2023 12:41:58 -0700 Message-ID: Subject: Re: Fwd: Memory corruption in multithreaded user space program while calling fork To: Linus Torvalds 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" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Stat-Signature: 9nzyobp8tesnezbo4dumptb4bndites5 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 57B1340002 X-HE-Tag: 1688845333-92697 X-HE-Meta: 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 RdiaGukV VGzHF2ZMJ5kP6SOf4Ng/FhsSKypIZbkJoW5qrDxPwEcdzLjmZDMqVLK09AgJF3WCJPSMKdmErYIq3herMchM8hbRBo6nCNzPB/+HsoobZUvp+hloAoIXdd9ozr4hvzEnDErtTUMsppGC8SUm1I4LTcDKCffykJNMzTX5qtwOC90I2CZXixJ0DAibAY3nyYadwqQwgJ48vMo108P1/o7GqRf2bRfBpdHIKKezGG5rsrtS7MgFgKdbuNlh1CWjNzECowa0IvBM+fO5wjrrxwnTRNR/5YqDjJE/B4QPjZY8SxgS91bHNRRtpOI7x+nValn5C9B1MPCgfWDiNIG/cFYNQtgyhdLc3mucDiw/qwZqGL1ZZNNY6J5xH8dpgIUQ0jCKrtdDt X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, Jul 8, 2023 at 12:23=E2=80=AFPM Linus Torvalds wrote: > > 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. Got it. I hope that's not the case and so far we haven't received an indication that the fixes were insufficient. > > 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. The patches applied cleanly to 6.4.y stable branch the last time I checked, so should not be a problem. Thanks, Suren. > > Linus