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Peter Anvin" , Jacob Pan , Jason Gunthorpe , Josh Poimboeuf , Joerg Roedel , Juri Lelli , Kent Overstreet , kinseyho@google.com, "Kirill A. Shutemov" , Lorenzo Stoakes , mgorman@suse.de, mic@digikod.net, michael.christie@oracle.com, Ingo Molnar , mjguzik@gmail.com, "Michael S. Tsirkin" , Nicholas Piggin , "Peter Zijlstra (Intel)" , Petr Mladek , Rick P Edgecombe , Steven Rostedt , Suren Baghdasaryan , Thomas Gleixner , Uladzislau Rezki , vincent.guittot@linaro.org, Valentin Schneider Content-Transfer-Encoding: quoted-printable Message-Id: <32BCF7CC-CBE8-45AD-B3D8-2856DD4FFF30@gmail.com> References: <20240311164638.2015063-1-pasha.tatashin@soleen.com> <20240311164638.2015063-12-pasha.tatashin@soleen.com> <3e180c07-53db-4acb-a75c-1a33447d81af@app.fastmail.com> <08EFDEDB-7BBB-4D9C-B7E5-D7370EC609BE@gmail.com> <11e673cf-8bfa-4493-ab86-2f1f97ddd732@app.fastmail.com> To: Andy Lutomirski X-Mailer: Apple Mail (2.3774.400.31) X-Rspamd-Queue-Id: 2475A4000C X-Rspam-User: X-Stat-Signature: jza4pwrqn3ccbfozcs7b7bx5bocctedw X-Rspamd-Server: rspam03 X-HE-Tag: 1710228057-103251 X-HE-Meta: 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 bNZFw30w gNglkiPhw6VFdMRS66esVL02eHxd8KQWF/o8GblNoAebukrGrHfwFp5JHFjzm4kTTqcJkxu1RQic6wEKw/JEJ0mvk5KAiNYh3KEo8wuyVjijMDOtIohcnQETSVixCRvPl0TFz4Avwxp4tC0AkRBHBfB83IFRQiaqbccid3lgeNOQsj3k= 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 12 Mar 2024, at 2:02, Andy Lutomirski wrote: >=20 > Doesn't this buy a new problem? Install a page, run the thread = without using the page but speculatively load the PTE as read-only into = the TLB, context-switch out the thread, (entirely safely and correctly) = determine that the page wasn't used, remove it from the PTE, use it for = something else and fill it with things that aren't zero, run the thread = again, and read from it. Now it has some other thread's data! Yes, you are correct. Bad idea of mine. Regardless of data leak, it = opens the door for subtle hard-to-analyze bugs where 2 reads return = different values.=