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Howlett" , Lorenzo Stoakes , Lu Baolu , Mike Rapoport , "H. Peter Anvin" , Shakeel Butt , Suren Baghdasaryan , Thomas Gleixner , Toshi Kani , Vlastimil Babka , Will Deacon , linux-mm@kvack.org, x86@kernel.org References: <20260729110807.797920433@infradead.org> <2ea2881c-7202-40e7-8fa2-f1c649c0d445@intel.com> <20260804200134.GK776954@noisy.programming.kicks-ass.net> From: Dave Hansen Content-Language: en-US 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: <20260804200134.GK776954@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: F25AE40008 X-Stat-Signature: n6m4kakh5n8ugex5cc96bjhh44eitxuq X-HE-Tag: 1785874084-333010 X-HE-Meta: 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 m6Cso4Zy ZtbcvAevuvoSqdeGt1TK+gQ3CXKHF3aASbQQJNTNbxrV+z+nv/0zuBtYRz24VCrrLB0zA33C0D/tG37hODBKSh4l+WlSC2oT3DpyuzT5/ums7A/RZqEHmdMo44yT2X7cC0QIX03NBN7Fxwpisl3P/7fXk01j2ONHV7eHPblVAp7LU5mZJKCVXnxN/sphokoDwUlB6Rq9NGoKdjAxMsag2+BiMJV+9HvYOmzye3j31blwvo7BNzCAQNmCnATJf4lbz1XkLoHb+KJew2NlDoQ9nCf+QsA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/4/26 13:01, Peter Zijlstra wrote: > On Tue, Aug 04, 2026 at 11:34:36AM -0700, Dave Hansen wrote: >> On 7/29/26 04:08, Peter Zijlstra wrote: >>> my take on how we should be 'fixing' this DEBUG_PAGEALLOC thing. It appears to >>> boot in qemu with debug_pagealloc=on and such things. >> The approach looks fine to me. The only thing we might want to do is add >> a warning of some kind in the split/join paths for CPA_DEBUG_PAGEALLOC. > So if you have lockdep enabled hitting them will scream bloody murder on > cpa_lock and pgd_lock. > > But if you want I can sprinkle more explicit warns 🙂 That's true. I was thinking of it more for self-documentation than actually getting it to spit out warnings in practice. Folks are always copying and pasting stuff and not realizing the context.