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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) > 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.=