In https://bugs.gentoo.org/801481 https://bugzilla.kernel.org/show_bug.cgi?id=213697 bowsingbetee noticed that the following setup causes kernel to complain about poisoning on memset(0) pages: - kernel command: page_poison=1 init_on_free=0 init_on_alloc=0 - kernel config: * CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y * CONFIG_INIT_ON_FREE_DEFAULT_ON=y * CONFIG_PAGE_POISONING=y v5.12 works ok, boots as: [ 0.009691][ T0] mem auto-init: stack:off, heap alloc:off, heap free:off v5.13 warns, boots as: [ 0.009746][ T0] mem auto-init: stack:off, heap alloc:on, heap free:on Current 5.14-rc1 is also affected: [ 0.009233][ T0] mem auto-init: stack:off, heap alloc:on, heap free:on [ 0.009234][ T0] mem auto-init: clearing system memory may take some time... [ 0.396784][ T0] pagealloc: memory corruption [ 0.396788][ T0] ffff888100000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ I attempted to bisect it and found the follwing relevant commits: Before the following commit no warnings were present: commit 51cba1ebc60df9c4ce034a9f5441169c0d0956c0 Author: Kees Cook <keescook@xxxxxxxxxxxx> Date: Thu Apr 1 16:23:43 2021 -0700 init_on_alloc: Optimize static branches Next after this commit kernel does not boot. Makes it harder to bisect the poisoning warning After the commit below kernel boots and already complains about poisoning of zero pages: commit 1bb5eab30d68c1a3d9dbc822e1895e6c06dbe748 Author: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Date: Thu Apr 29 23:00:02 2021 -0700 kasan, mm: integrate page_alloc init with HW_TAGS It looks like a case of page_poison=1 not having enough of a priority over init_on_free=0 init_on_alloc=0 at early boot. -- Sergei
