On Wed, Mar 23, 2022 at 2:02 PM Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote: > > On 2022-03-23 12:48:29 [+0100], Vlastimil Babka wrote: > > > +#ifdef CONFIG_KASAN_HW_TAGS > > > #define ___GFP_SKIP_KASAN_POISON 0x1000000u > > > +#else > > > +#define ___GFP_SKIP_KASAN_POISON 0 > > > +#endif > > > #ifdef CONFIG_LOCKDEP > > > #define ___GFP_NOLOCKDEP 0x2000000u > > > #else > > > @@ -251,7 +255,9 @@ struct vm_area_struct; > > > #define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP) > > > > > > /* Room for N __GFP_FOO bits */ > > > -#define __GFP_BITS_SHIFT (25 + IS_ENABLED(CONFIG_LOCKDEP)) > > > +#define __GFP_BITS_SHIFT (24 + \ > > > + IS_ENABLED(CONFIG_KASAN_HW_TAGS) + \ > > > + IS_ENABLED(CONFIG_LOCKDEP)) > > > > This breaks __GFP_NOLOCKDEP, see: > > https://lore.kernel.org/all/YjoJ4CzB3yfWSV1F@xxxxxxxxxxxxx/ > > This could work because ___GFP_NOLOCKDEP is still 0x2000000u. In > ("kasan, page_alloc: allow skipping memory init for HW_TAGS") > https://lore.kernel.org/all/0d53efeff345de7d708e0baa0d8829167772521e.1643047180.git.andreyknvl@xxxxxxxxxx/ > > This is replaced with 0x8000000u which breaks lockdep. > > Sebastian Hi Sebastian, Indeed, sorry for breaking lockdep. Thank you for the report! I wonder what's the proper fix for this. Perhaps, don't hide KASAN GFP bits under CONFIG_KASAN_HW_TAGS? And then do: #define __GFP_BITS_SHIFT (27 + IS_ENABLED(CONFIG_LOCKDEP)) Vlastimil, Andrew do you have any preference? If my suggestion sounds good, Andrew, could you directly apply the changes? They are needed for these 3 patches: kasan, page_alloc: allow skipping memory init for HW_TAGS kasan, page_alloc: allow skipping unpoisoning for HW_TAGS kasan, mm: only define ___GFP_SKIP_KASAN_POISON with HW_TAGS As these depend on each other, I can't send separate patches that can be folded for all 3. Thanks!
