Re: [PATCH v6 27/39] kasan, mm: only define ___GFP_SKIP_KASAN_POISON with HW_TAGS

Vlastimil Babka
2022-03-23T11:49:59Z

On 1/24/22 19:05, andrey.konovalov@linux.dev wrote:
> From: Andrey Konovalov <andreyknvl@google.com>
>
> Only define the ___GFP_SKIP_KASAN_POISON flag when CONFIG_KASAN_HW_TAGS
> is enabled.
>
> This patch it not useful by itself, but it prepares the code for
> additions of new KASAN-specific GFP patches.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
>
> ---
>
> Changes v3->v4:
> - This is a new patch.
> ---
> include/linux/gfp.h | 8 +++++++-
> include/trace/events/mmflags.h | 12 +++++++++---
> 2 files changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index 581a1f47b8a2..96f707931770 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -54,7 +54,11 @@ struct vm_area_struct;
> #define ___GFP_THISNODE 0x200000u
> #define ___GFP_ACCOUNT 0x400000u
> #define ___GFP_ZEROTAGS 0x800000u
> +#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@linutronix.de/

> #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
>
> /**
> diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
> index 116ed4d5d0f8..cb4520374e2c 100644
> --- a/include/trace/events/mmflags.h
> +++ b/include/trace/events/mmflags.h
> @@ -49,12 +49,18 @@
> {(unsigned long)__GFP_RECLAIM, "__GFP_RECLAIM"}, \
> {(unsigned long)__GFP_DIRECT_RECLAIM, "__GFP_DIRECT_RECLAIM"},\
> {(unsigned long)__GFP_KSWAPD_RECLAIM, "__GFP_KSWAPD_RECLAIM"},\
> - {(unsigned long)__GFP_ZEROTAGS, "__GFP_ZEROTAGS"}, \
> - {(unsigned long)__GFP_SKIP_KASAN_POISON,"__GFP_SKIP_KASAN_POISON"}\
> + {(unsigned long)__GFP_ZEROTAGS, "__GFP_ZEROTAGS"} \
> +
> +#ifdef CONFIG_KASAN_HW_TAGS
> +#define __def_gfpflag_names_kasan \
> + , {(unsigned long)__GFP_SKIP_KASAN_POISON, "__GFP_SKIP_KASAN_POISON"}
> +#else
> +#define __def_gfpflag_names_kasan
> +#endif
>
> #define show_gfp_flags(flags) \
> (flags) ? __print_flags(flags, "|", \
> - __def_gfpflag_names \
> + __def_gfpflag_names __def_gfpflag_names_kasan \
> ) : "none"
>
> #ifdef CONFIG_MMU