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Peter Anvin" , Andy Lutomirski , Peter Zijlstra , "Kirill A. Shutemov" , Rick Edgecombe , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: D2AE58001A X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: cy8tz7gnjgc94ytjm4rp7ehreadr1zmm X-HE-Tag: 1719941983-997988 X-HE-Meta: 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 Uw1GXPhK AoFiFF3KgVfdIKWnW43t3BksTWuDPSSazMeIf6PurrzhiHmEbk7LpzQxi+f1PB6J3Doa04PPGXTJDWarjmvDN3UGdaxMQ2L5oMgzJkT0JZDGwKH6eeUdlmJ7badLFCr9wSftaLhuDvjsbf35I9QF5zVfTkAVBGZiob2kTCgDIo4jC/ZJFnkoS5bOsKJJJvZjOzgQmxJE02CPRljVIap2nJYnmsByq6p8pF3dgjY9/2xo2Sq51kD/R9cpvJm0zWD0bHevE 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: List-Subscribe: List-Unsubscribe: On Tue, Jul 2, 2024 at 10:36=E2=80=AFAM Andrew Morton wrote: > > On Tue, 2 Jul 2024 13:21:36 +0000 Yosry Ahmed wr= ote: > > > This series has fixups and cleanups for LAM. Most importantly, patch 1 > > fixes a sycnhronization issue that may cause crashes of userspace > > applications. This is a resend of v3, rebased on top of v6.10-rc6. > > "Crashes of userspace applications" is bad. Yet the patchset has been > floating about for four months. > > It's unclear (to me) how serious this is. Can you please explain how > common this is, what the userspace application needs to do to trigger > this, etc? I don't think it would be common. The bug only happens on new hardware supporting LAM, and it happens in a specific scenario where a userspace task enables LAM while a kthread is using (borrowing) its mm_struct on another CPU. So it is possible but I certainly wouldn't call it common or easily trigger= able.