On Mon, Aug 19, 2024 at 6:46 PM Andrew Morton <[email protected]> wrote: > > On Mon, 19 Aug 2024 21:40:34 +0100 Matthew Wilcox <[email protected]> wrote: > > > On Mon, Aug 19, 2024 at 01:39:16PM -0700, Suren Baghdasaryan wrote: > > > On Mon, Aug 19, 2024 at 12:34 PM Matthew Wilcox <[email protected]> > > > wrote: > > > > So if ALLOC_TAG_REF_WIDTH is big enough, it's going to force last_cpupid > > > > into struct page. > > > > > > Thanks for taking a look! > > > Yes, but how is this field different from say KASAN_TAG_WIDTH which > > > can also force last_cpupid out of page flags? > > > > Because KASAN isn't for production use? > > > > > > That will misalign struct page and disable HVO -- with no warning! > > > > > > mminit_verify_pageflags_layout already has a mminit_dprintk() to > > > indicate this condition. Is that not enough? > > > > Fair. > > Is a BUILD_BUG_ON() feasible here?
We could, but I didn't think we should prevent people from having such a configuration if that's what they need...
