On Mon, Dec 13, 2021 at 10:54PM +0100, andrey.konovalov@xxxxxxxxx wrote: [...] > > + /* > + * Skip page_alloc poisoning and zeroing for pages backing VM_ALLOC > + * mappings. Only effective in HW_TAGS mode. > + */ > + gfp &= __GFP_SKIP_KASAN_UNPOISON & __GFP_SKIP_ZERO; This will turn gfp == 0 always. Should it have been gfp |= __GFP_SKIP_KASAN_UNPOISON | __GFP_SKIP_ZERO Also, not sure it matters, but on non-KASAN builds, this will now always generate an extra instruction. You could conditionally define GFP_SKIP* only in the KASAN modes that need them, otherwise they become 0, so the compiler optimizes this out. (Although I think it does does complicate GFP_SHIFT a little?)
