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a=rsa-sha256; c=relaxed/relaxed; d=stgolabs.net; s=dreamhost; t=1675703304; bh=zIznFMDI6Lij7FER4Z78PRmQWP5O6fXpz/Om0xIe8N4=; h=Date:From:To:Cc:Subject:Content-Type; b=mXp8B55Ok+VGVQ3wv0CNCIijFteqatu7t72n1gJglNvPTOuL4d9ysY3cRFU1o+CDB dBTfkUddNW9DaaaEP8Hz8mkueG4EQLRNmk35aa9i1AvdaBmQbIgT/bN6Nfi7MruNsS w+3S3BqMeG9kySn/izBNQ7WiXacrbF5UwX/BBVUvVSto+n895E2CUlPdubePVhDW+U 6aBONJrcOsSt4iTjB4AYZvlwP7YNiEnlU2YUCwQoszAuCoIuvfWSheOQiKcqz4SsbH XzFYLo+3c4Lb9sX6PRWWwN5uBJfQOFi5MfflGJPeufCoEoABxWPObHmIEW8ilkbKvR Rk87VjBdNWyBA== Date: Mon, 6 Feb 2023 08:40:56 -0800 From: Davidlohr Bueso To: Gregory Price Cc: Dan Williams , linux-cxl@vger.kernel.org, David Hildenbrand , Kees Cook , stable@vger.kernel.org, Dave Hansen , Michal Hocko , linux-mm@kvack.org, linux-acpi@vger.kernel.org Subject: Re: [PATCH 00/18] CXL RAM and the 'Soft Reserved' => 'System RAM' default Message-ID: <20230206164056.a4ifv3k4juadlazl@offworld> Mail-Followup-To: Gregory Price , Dan Williams , linux-cxl@vger.kernel.org, David Hildenbrand , Kees Cook , stable@vger.kernel.org, Dave Hansen , Michal Hocko , linux-mm@kvack.org, linux-acpi@vger.kernel.org References: <167564534874.847146.5222419648551436750.stgit@dwillia2-xfh.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20220429 X-Rspamd-Queue-Id: 05A7140027 X-Stat-Signature: gk8u9px9ejbew8w8kuy8ostemxk874ao X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1675703306-812483 X-HE-Meta: U2FsdGVkX19XmRBESDuRZGvsglLnkJWRr84GHsLwEWAp293LioOWgclnWvKYc0Lb1I4IAosMDz9bbv025qtq4Jx1Rd6IdTSS2qqaKv+0y59Q2AOa8uUUCdvRAALw1aNYrDH+E+ZgBz8BNlMQdTANkkjxEKZnxXUUBl2gMgiunl8fVgdm3O6cpgpEiGJdcejYsIsMTLLXaJXf3VigEIJlMwHNVJInhq01J5lvtUQP0RaFFRSbapzv8mlTmjMw4Oxsx65jybcPZX8BxxTfU8KWc3dch9Zrnfo7L/D7mORCWXC7O+WfuM3yP7QrFLGoVdytof191wioLIT7Z+VLHQfP/6RMccEWLUPWBxSuU4kwOyCy8RoNzg7aQNFV6m5dxN8fxlO6w9tmu5yeopUoAup/oPTjnPeVIX0mQEiTcK7hGSqFm3+EC+3rxjNun2UgF2o8zTyfZ+4VstVy5AkIstKGGkc4VCefBT4xMQAKnQmbwBDfITpes3qHlfI+oJ4fs/zL8UUJmYQ2RY7tlW2Wtlgs6sBvkR2RriM2dSjrQCYBE8dE9i/6TcVw+G4a1fxUnZxcMbavE/lXEonwODiTiPZ4U7MCkznsKBqA/wB9YTgJIcazG6z+LVPYCV8m10i8Gcj3NHf9fzBNJRHuRcxi9gxlCjZS7yHu+3IkHMj34j/kwOJ8a5KXVsTZ3emO1HCjQYuK14jrh+JDqui0r//7wIsqMjeh2qx9jFcuhh0he4XfI+rt1fNsfPsVwuFS/Vah7kOVE7advsqsJgCPvx0zi0nT0f/CuMh2D0QBkVviAFqOIXcJgBBhJYDbSaLkKCYKHEUQa+aGylWt/WGifxr2WvhPyCgxZLu5cJAZ7fzCfunBCcVDTdfBEdFdd9SE1+FkVTvsXESAeRscxJD1/V5U98e35mc2ThOxgtuGA8CPEhFzvQV4c8UTckcx2TzKEm/5N2vOCJk436iyUVHURPiG0Ns aTnXpyBK Lyhsk0iNqIawA+lYVt2Urs64GtfDV9tS9oMf0A26TzftqAl72H/urfZRlNqcjAWufkeLRX/0f+KUGtExdhhlHw+srZukRjovERUOoS8R2sNmqlNRZq3ksqPu0lEWxUixp7mU2yCgG1eynKZ7C9CwiYd+P7i5aPUusLVIiCLW+Z1Gat8eA9Rniy7LhhoNitK6c9UumeylR6F7bX0+xc46rclI13aLjkxJIkfWQwuPmdYXAc7R7/syfooAtUQdLPvlbitOMnqokjHHEKaGY6WVAyeACo6NMr1b2Dz29RhhELNn3s/Ry86pa/a6Owg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.003722, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, 06 Feb 2023, Gregory Price wrote: >On Sun, Feb 05, 2023 at 05:02:29PM -0800, Dan Williams wrote: >> Summary: >> -------- >> >> CXL RAM support allows for the dynamic provisioning of new CXL RAM >> regions, and more routinely, assembling a region from an existing >> configuration established by platform-firmware. The latter is motivated >> by CXL memory RAS (Reliability, Availability and Serviceability) >> support, that requires associating device events with System Physical >> Address ranges and vice versa. >> >> The 'Soft Reserved' policy rework arranges for performance >> differentiated memory like CXL attached DRAM, or high-bandwidth memory, >> to be designated for 'System RAM' by default, rather than the device-dax >> dedicated access mode. That current device-dax default is confusing and >> surprising for the Pareto of users that do not expect memory to be >> quarantined for dedicated access by default. Most users expect all >> 'System RAM'-capable memory to show up in FREE(1). > >Leverage the same QEMU branch, machine, and configuration as my prior >tests, i'm now experiencing a kernel panic on boot. Will debug a bit >in the morning, but here is the stack trace i'm seeing > >Saw this in both 1 and 2 root port configurations I also see it in "regular" pmem setups, and narrowed it down to this change in the last patch: -module_init(cxl_acpi_init); +/* load before dax_hmem sees 'Soft Reserved' CXL ranges */ +subsys_initcall(cxl_acpi_init);