On 01/04/2017 02:46 PM, Khalid Aziz wrote: > This patch extends mprotect to enable ADI (TSTATE.mcde), enable/disable > MCD (Memory Corruption Detection) on selected memory ranges, enable > TTE.mcd in PTEs, return ADI parameters to userspace and save/restore ADI > version tags on page swap out/in. I'm a bit confused why we need all the mechanics with set_swp_pte_at(). For pkeys, for instance, all of the PTEs under a given VMA share a pkey. When swapping something in, we just get the pkey out of the VMA and populate the PTE. ADI doesn't seem to have a similar restriction. The feature is turned on or off at a VMA granularity, but we do not (or can enforce that all pages under a given VMA must share a tag. But this leads to an interesting question: is the tag associated with the (populated?) pte, or the virtual address? Can you have tags associated with non-present addresses? What's the mechanism that clears the tags at munmap() or MADV_FREE time? Is the tag storage a precious resource? Can it be exhausted? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>