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J . Bottomley" , Helge Deller , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Naveen N Rao , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , Yoshinori Sato , Rich Felker , John Paul Adrian Glaubitz , "David S . Miller" , Andreas Larsson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Muchun Song , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Lorenzo Stoakes , shuah , Christoph Hellwig , Michal Hocko , "Kirill A. Shutemov" , Chris Torek , Linux-Arch , linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, "linux-csky@vger.kernel.org" , loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-abi-devel@lists.sourceforge.net Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 2228A140002 X-Stat-Signature: gsy5dox4j6wgaks9i1jf7qy7deypz4y7 X-Rspam-User: X-HE-Tag: 1725614086-820979 X-HE-Meta: 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 NoT4d3Mv 0JUJjpmqpH4S8YjuklwDFM1iIJ+xGzc7tdE9ibdWiyKzQUuuXONLvq2B8JjL72i69Hc1ideaTqKeSXmgsaxh4+dRvUQO+nVzOjmYp0a+mP6NrEfBE0bWz6V4lpZPqeP/7OVRwDtPDyZnvyxo0DhIihrCsaijklIamwe55KnmjFE6XRR5NfPIuvhwe4L6rnlTlku17CiTfz5cRO7N+S7eNhatAqVwtiWjB93kqwh7kYFhGQH/Y4f5oRt2iS6cuma6Qkb8iNXxqU+NVdl/f4n0wU9GfH1pjrrSD/SEgVd/JJOE1uaYFhvP25quJA5X3v9wm4PjK3kmEkHgJ1sXxpIY+cSujCPopZH72+CrdG8JBXZkt908uNyt5Xelai/RPmEgRLgLdy9nZT9+yWbCJF8WplLZ8kkrSlT2eO5zSiGOkkf1YSdjVBPoL/mYLF1SeQUJtXnY8u/JwXDDhCSE= 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 Fri, Sep 6, 2024 at 3:18=E2=80=AFPM Arnd Bergmann wrote: > > On Thu, Sep 5, 2024, at 21:15, Charlie Jenkins wrote: > > Create a personality flag ADDR_LIMIT_47BIT to support applications > > that wish to transition from running in environments that support at > > most 47-bit VAs to environments that support larger VAs. This > > personality can be set to cause all allocations to be below the 47-bit > > boundary. Using MAP_FIXED with mmap() will bypass this restriction. > > > > Signed-off-by: Charlie Jenkins > > I think having an architecture-independent mechanism to limit the size > of the 64-bit address space is useful in general, and we've discussed > the same thing for arm64 in the past, though we have not actually > reached an agreement on the ABI previously. > > > @@ -22,6 +22,7 @@ enum { > > WHOLE_SECONDS =3D 0x2000000, > > STICKY_TIMEOUTS =3D 0x4000000, > > ADDR_LIMIT_3GB =3D 0x8000000, > > + ADDR_LIMIT_47BIT =3D 0x10000000, > > }; > > I'm a bit worried about having this done specifically in the > personality flag bits, as they are rather limited. We obviously > don't want to add many more such flags when there could be > a way to just set the default limit. > > It's also unclear to me how we want this flag to interact with > the existing logic in arch_get_mmap_end(), which attempts to > limit the default mapping to a 47-bit address space already. To optimize RISC-V progress, I recommend: Step 1: Approve the patch. Step 2: Update Go and OpenJDK's RISC-V backend to utilize it. Step 3: Wait approximately several iterations for Go & OpenJDK Step 4: Remove the 47-bit constraint in arch_get_mmap_end() > > For some reason, it appears that the arch_get_mmap_end() > logic on RISC-V defaults to the maximum address > space for the 'addr=3D=3D0' case which is inconsistentn with > the other architectures, so we should probably fix that > part first, possibly moving more of that logic into a > shared implementation. > > Arnd > --=20 Best Regards Guo Ren