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Peter Anvin" , Mike Rapoport , Lorenzo Stoakes , Pedro Falcato , Toshi Kani , linux-mm@kvack.org, regressions@lists.linux.dev, linux-kernel@vger.kernel.org References: <20260924051011.21237-1-mikhail.v.gavrilov@gmail.com> Content-Language: en-US From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; keydata= xsFNBE6HMP0BEADIMA3XYkQfF3dwHlj58Yjsc4E5y5G67cfbt8dvaUq2fx1lR0K9h1bOI6fC oAiUXvGAOxPDsB/P6UEOISPpLl5IuYsSwAeZGkdQ5g6m1xq7AlDJQZddhr/1DC/nMVa/2BoY 2UnKuZuSBu7lgOE193+7Uks3416N2hTkyKUSNkduyoZ9F5twiBhxPJwPtn/wnch6n5RsoXsb ygOEDxLEsSk/7eyFycjE+btUtAWZtx+HseyaGfqkZK0Z9bT1lsaHecmB203xShwCPT49Blxz VOab8668QpaEOdLGhtvrVYVK7x4skyT3nGWcgDCl5/Vp3TWA4K+IofwvXzX2ON/Mj7aQwf5W iC+3nWC7q0uxKwwsddJ0Nu+dpA/UORQWa1NiAftEoSpk5+nUUi0WE+5DRm0H+TXKBWMGNCFn c6+EKg5zQaa8KqymHcOrSXNPmzJuXvDQ8uj2J8XuzCZfK4uy1+YdIr0yyEMI7mdh4KX50LO1 pmowEqDh7dLShTOif/7UtQYrzYq9cPnjU2ZW4qd5Qz2joSGTG9eCXLz5PRe5SqHxv6ljk8mb ApNuY7bOXO/A7T2j5RwXIlcmssqIjBcxsRRoIbpCwWWGjkYjzYCjgsNFL6rt4OL11OUF37wL QcTl7fbCGv53KfKPdYD5hcbguLKi/aCccJK18ZwNjFhqr4MliQARAQABzUVEYXZpZCBDaHJp c3RvcGhlciBIYW5zZW4gKEludGVsIFdvcmsgQWRkcmVzcykgPGRhdmUuaGFuc2VuQGludGVs LmNvbT7CwXgEEwECACIFAlQ+9J0CGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEGg1 lTBwyZKwLZUP/0dnbhDc229u2u6WtK1s1cSd9WsflGXGagkR6liJ4um3XCfYWDHvIdkHYC1t MNcVHFBwmQkawxsYvgO8kXT3SaFZe4ISfB4K4CL2qp4JO+nJdlFUbZI7cz/Td9z8nHjMcWYF IQuTsWOLs/LBMTs+ANumibtw6UkiGVD3dfHJAOPNApjVr+M0P/lVmTeP8w0uVcd2syiaU5jB aht9CYATn+ytFGWZnBEEQFnqcibIaOrmoBLu2b3fKJEd8Jp7NHDSIdrvrMjYynmc6sZKUqH2 I1qOevaa8jUg7wlLJAWGfIqnu85kkqrVOkbNbk4TPub7VOqA6qG5GCNEIv6ZY7HLYd/vAkVY E8Plzq/NwLAuOWxvGrOl7OPuwVeR4hBDfcrNb990MFPpjGgACzAZyjdmYoMu8j3/MAEW4P0z F5+EYJAOZ+z212y1pchNNauehORXgjrNKsZwxwKpPY9qb84E3O9KYpwfATsqOoQ6tTgr+1BR CCwP712H+E9U5HJ0iibN/CDZFVPL1bRerHziuwuQuvE0qWg0+0SChFe9oq0KAwEkVs6ZDMB2 P16MieEEQ6StQRlvy2YBv80L1TMl3T90Bo1UUn6ARXEpcbFE0/aORH/jEXcRteb+vuik5UGY 5TsyLYdPur3TXm7XDBdmmyQVJjnJKYK9AQxj95KlXLVO38lczsFNBFRjzmoBEACyAxbvUEhd GDGNg0JhDdezyTdN8C9BFsdxyTLnSH31NRiyp1QtuxvcqGZjb2trDVuCbIzRrgMZLVgo3upr MIOx1CXEgmn23Zhh0EpdVHM8IKx9Z7V0r+rrpRWFE8/wQZngKYVi49PGoZj50ZEifEJ5qn/H Nsp2+Y+bTUjDdgWMATg9DiFMyv8fvoqgNsNyrrZTnSgoLzdxr89FGHZCoSoAK8gfgFHuO54B lI8QOfPDG9WDPJ66HCodjTlBEr/Cwq6GruxS5i2Y33YVqxvFvDa1tUtl+iJ2SWKS9kCai2DR 3BwVONJEYSDQaven/EHMlY1q8Vln3lGPsS11vSUK3QcNJjmrgYxH5KsVsf6PNRj9mp8Z1kIG qjRx08+nnyStWC0gZH6NrYyS9rpqH3j+hA2WcI7De51L4Rv9pFwzp161mvtc6eC/GxaiUGuH BNAVP0PY0fqvIC68p3rLIAW3f97uv4ce2RSQ7LbsPsimOeCo/5vgS6YQsj83E+AipPr09Caj 0hloj+hFoqiticNpmsxdWKoOsV0PftcQvBCCYuhKbZV9s5hjt9qn8CE86A5g5KqDf83Fxqm/ vXKgHNFHE5zgXGZnrmaf6resQzbvJHO0Fb0CcIohzrpPaL3YepcLDoCCgElGMGQjdCcSQ+Ci FCRl0Bvyj1YZUql+ZkptgGjikQARAQABwsFfBBgBAgAJBQJUY85qAhsMAAoJEGg1lTBwyZKw l4IQAIKHs/9po4spZDFyfDjunimEhVHqlUt7ggR1Hsl/tkvTSze8pI1P6dGp2XW6AnH1iayn yRcoyT0ZJ+Zmm4xAH1zqKjWplzqdb/dO28qk0bPso8+1oPO8oDhLm1+tY+cOvufXkBTm+whm +AyNTjaCRt6aSMnA/QHVGSJ8grrTJCoACVNhnXg/R0g90g8iV8Q+IBZyDkG0tBThaDdw1B2l asInUTeb9EiVfL/Zjdg5VWiF9LL7iS+9hTeVdR09vThQ/DhVbCNxVk+DtyBHsjOKifrVsYep WpRGBIAu3bK8eXtyvrw1igWTNs2wazJ71+0z2jMzbclKAyRHKU9JdN6Hkkgr2nPb561yjcB8 sIq1pFXKyO+nKy6SZYxOvHxCcjk2fkw6UmPU6/j/nQlj2lfOAgNVKuDLothIxzi8pndB8Jju KktE5HJqUUMXePkAYIxEQ0mMc8Po7tuXdejgPMwgP7x65xtfEqI0RuzbUioFltsp1jUaRwQZ MTsCeQDdjpgHsj+P2ZDeEKCbma4m6Ez/YWs4+zDm1X8uZDkZcfQlD9NldbKDJEXLIjYWo1PH hYepSffIWPyvBMBTW2W5FRjJ4vLRrJSUoEfJuPQ3vW9Y73foyo/qFoURHO48AinGPZ7PC7TF vUaNOTjKedrqHkaOcqB185ahG2had0xnFsDPlx5y In-Reply-To: <20260924051011.21237-1-mikhail.v.gavrilov@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 521614000A X-Stat-Signature: ibkjwnqme7euapwdtrb7gt7rk3j3rgj6 X-Rspam-User: X-HE-Tag: 1790268320-860584 X-HE-Meta: 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 2Tr4plh5 AnuOPseVExTzFXNHlAXcBVO2RZG+gcQjZ+Shek0Df5QaTbZI2Biz/6pwx/6SLwLWlanxcHuIBhypLnYPmNm42mTS/dVhPGyRzPUeyDNhscf+i6MtP4MLU4EVVjxAbKaly9KBTGriZnqXpDzRjtZ8OLxcpqNh5GoamNgfwj6Je94Vwjq3hY88l5idQIdsbIltjPxp+ksEM/AfQJXNo4TjEXJ1KF7KmuE5oErpH5oC8aeKGa8/mX7dOKDe61mSLlt3TThmKP8Lw224ZDktYLAA5xiZddXIlg6qh8hhAl6QE7yYvTjcInPSSBkfiD1B7E2QCfdYobomz+wOPwTA= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/23/26 22:10, Mikhail Gavrilov wrote: > On 9/23/26 16:07, Dave Hansen wrote: >> There are a few things we need to figure out like having >> pmd_free_pte_page() return 'int' when it doesn't ever fail, the >> comments, and the reverse Christmas tree. > > One data point for the return value: the x86-PAE pmd_free_pte_page() > does fail. It returns pmd_none(*pmd), and vmap_try_huge_pmd() relies > on that to keep ioremap() from replacing an existing PTE table there > (the comment above it is about the sync'd PMD entries). Huge PMD vmap > is enabled on PAE whenever the CPU has PSE. Oh, that's just kinda silly. We should just zap that version and huge PMD vmap on 32-bit. > pud_free_pmd_page() has no such case: the PUD level is 64-bit only on > x86, and with v2 applied the x86-64 version, like the arm64, riscv and > powerpc ones, always returns 1. Yeah, all the ones for CPUs from this millennium are OK. >> I'll dig into it a bit tomorrow and see what I come up with. > > Thanks. This box reaches pud_free_pmd_page() on every boot I have > checked, so I can run whatever you come up with through the same > boot-time kprobe and reproducer check. I think I'll just take your version since you actually, you know, compiled it and all. ;)