On Fri, 26 Mar 2021 16:00:34 +0100 Andrey Konovalov <andreyknvl@xxxxxxxxx> wrote: > On Fri, Mar 26, 2021 at 2:49 PM David Hildenbrand <david@xxxxxxxxxx> wrote: > > > > > I observed use of poisoned pages as the crash on ia64 booted with > > > init_on_free=1 init_on_alloc=1 (CONFIG_PAGE_POISONING=y config). > > > There pmd page contained 0xaaaaaaaa poison pages and led to early crash. > > > > > > The change drops the assumption that init_on_free=1 guarantees free > > > pages to contain zeros. > > > > > > Alternative would be to make interaction between runtime poisoning and > > > sanitizing options and build-time debug flags like CONFIG_PAGE_POISONING > > > more coherent. I took the simpler path. > > > > > > > I thought latest work be Vlastimil tried to tackle that. To me, it feels > > like page_poison=on and init_on_free=1 should bail out and disable one > > of both things. Having both at the same time doesn't sound helpful. > > This is exactly how it works, see init_mem_debugging_and_hardening(). > > Sergei, could you elaborate more on what kind of crash this patch is > trying to fix? Where does it happen and why? Yeah, I see I misinterpreted page_poison=on handling and misled you all. Something else poisons a page when it should have not. I'll answer in more detail to Vlastimil's email upthread and will provide more detail of the unexpected poisoning I see. -- Sergei
