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Wong" To: Lorenzo Stoakes Cc: Christoph Hellwig , Kent Overstreet , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-bcachefs@vger.kernel.org, Kent Overstreet , Andrew Morton , Uladzislau Rezki , linux-mm@kvack.org Subject: Re: [PATCH 07/32] mm: Bring back vmalloc_exec Message-ID: <20230509214319.GA858791@frogsfrogsfrogs> References: <20230509165657.1735798-1-kent.overstreet@linux.dev> <20230509165657.1735798-8-kent.overstreet@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Stat-Signature: wis7dhgp916jqw49aww9f3sb5doda7gk X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 522F0180003 X-HE-Tag: 1683668602-651873 X-HE-Meta: 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 qdsbqkdz IW4oGzVFxXs6Gp8qOG9G1h6W5MG7RfqW5DeAQqE/96I7fk5M83YXEyflCjszKXKG8nsW1ePq/KHJDWi2iZgqXQT/wVUq0Yjl3hXklyUoCf0YN3ifgQdf+xASXjWhZXuUT3sueX+YzjZ7IQLOI8DFs686dhOwPq1pboYcB5cUKyQcDJ1NlS0fG6R4vvJ+6Ll4KqQZU/xBiv9csT9pzcQ2bL8CbdphvczZrnFxwZ7i/65oGLAB2cEpj1EGukr8L4q2NC+kwL5H72aYkom0KZZuAJGy5SuSflI4W1sCGeeMpYEOgwVT34D8kVcwDs6D9G930X4kqi9W8lkD4pjk9tK6qUuEE6xyF+cL3imoajKvoOUAG7abS0Inc7ykhymLooikr6oSYAhsKBMEiHBWdJ4TQnErOqCdO7sTgq69esG0Ej22QrBA= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000068, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, May 09, 2023 at 02:12:41PM -0700, Lorenzo Stoakes wrote: > On Tue, May 09, 2023 at 01:46:09PM -0700, Christoph Hellwig wrote: > > On Tue, May 09, 2023 at 12:56:32PM -0400, Kent Overstreet wrote: > > > From: Kent Overstreet > > > > > > This is needed for bcachefs, which dynamically generates per-btree node > > > unpack functions. > > > > No, we will never add back a way for random code allocating executable > > memory in kernel space. > > Yeah I think I glossed over this aspect a bit as it looks ostensibly like simply > reinstating a helper function because the code is now used in more than one > place (at lsf/mm so a little distracted :) > > But it being exported is a problem. Perhaps there's another way of acheving the > same aim without having to do so? I already trolled Kent with this on IRC, but for the parts of bcachefs that want better assembly code than whatever gcc generates from the C source, could you compile code to BPF and then let the BPF JIT engines turn that into machine code for you? (also distracted by LSFMM) --D