On Sat, Feb 24, 2024 at 7:03 AM Christophe JAILLET <christophe.jaillet@xxxxxxxxxx> wrote: > > Le 24/02/2024 à 02:58, Suren Baghdasaryan a écrit : > > Introduce GFP bits enumeration to let compiler track the number of used > > bits (which depends on the config options) instead of hardcoding them. > > That simplifies __GFP_BITS_SHIFT calculation. > > > > Suggested-by: Petr Tesařík <petr@xxxxxxxxxxx> > > Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx> > > Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> > > Reviewed-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx> > > Acked-by: Michal Hocko <mhocko@xxxxxxxx> > > --- > > Changes from v4 [1]: > > - Split from the series [2] as a stand-alone patch, per Michal Hocko > > - Added Reviewed-by, per Pasha Tatashin > > - Added Acked-by, per Michal Hocko > > > > [1] https://lore.kernel.org/all/20240221194052.927623-7-surenb@xxxxxxxxxx/ > > [2] https://lore.kernel.org/all/20240221194052.927623-1-surenb@xxxxxxxxxx/ > > > > include/linux/gfp_types.h | 90 +++++++++++++++++++++++++++------------ > > 1 file changed, 62 insertions(+), 28 deletions(-) > > > > diff --git a/include/linux/gfp_types.h b/include/linux/gfp_types.h > > index 1b6053da8754..868c8fb1bbc1 100644 > > --- a/include/linux/gfp_types.h > > +++ b/include/linux/gfp_types.h > > @@ -21,44 +21,78 @@ typedef unsigned int __bitwise gfp_t; > > * include/trace/events/mmflags.h and tools/perf/builtin-kmem.c > > */ > > > > +enum { > > + ___GFP_DMA_BIT, > > + ___GFP_HIGHMEM_BIT, > > + ___GFP_DMA32_BIT, > > + ___GFP_MOVABLE_BIT, > > + ___GFP_RECLAIMABLE_BIT, > > + ___GFP_HIGH_BIT, > > + ___GFP_IO_BIT, > > + ___GFP_FS_BIT, > > + ___GFP_ZERO_BIT, > > + ___GFP_UNUSED_BIT, /* 0x200u unused */ > > Hi, > > what is the need to have this ___GFP_UNUSED_BIT now? Hi! We can remove it but then all values will shift. That should be safe to do now but I prefer one patch to do only one thing. We can add a separate patch to do further cleanup of unused values. > > > + ___GFP_DIRECT_RECLAIM_BIT, > > + ___GFP_KSWAPD_RECLAIM_BIT, > > + ___GFP_WRITE_BIT, > > + ___GFP_NOWARN_BIT, > > + ___GFP_RETRY_MAYFAIL_BIT, > > + ___GFP_NOFAIL_BIT, > > + ___GFP_NORETRY_BIT, > > + ___GFP_MEMALLOC_BIT, > > + ___GFP_COMP_BIT, > > + ___GFP_NOMEMALLOC_BIT, > > + ___GFP_HARDWALL_BIT, > > + ___GFP_THISNODE_BIT, > > + ___GFP_ACCOUNT_BIT, > > + ___GFP_ZEROTAGS_BIT, > > +#ifdef CONFIG_KASAN_HW_TAGS > > + ___GFP_SKIP_ZERO_BIT, > > + ___GFP_SKIP_KASAN_BIT, > > +#endif > > +#ifdef CONFIG_LOCKDEP > > + ___GFP_NOLOCKDEP_BIT, > > +#endif > > + ___GFP_LAST_BIT > > +}; > > Does it make sense to have something like: > BUILD_BUG_ON(___GFP_LAST_BIT > BITS_PER_LONG, "blah"); I suppose that would not hurt, except gfp_t is unsigned int, not long. Something like this would work I think: BUILD_BUG_ON_MSG(___GFP_LAST_BIT > BITS_PER_TYPE(gfp_t), "GFP bit overflow"); except I'm not sure where to put this check. One of the __init functions in page_alloc.c would probably work but none seem to be appropriate. mm_core_init() perhaps? Other ideas? > (should we need to use BIT_ULL() one day) > > > + > > /* Plain integer GFP bitmasks. Do not use this directly. */ > > -#define ___GFP_DMA 0x01u > > -#define ___GFP_HIGHMEM 0x02u > > -#define ___GFP_DMA32 0x04u > > -#define ___GFP_MOVABLE 0x08u > > -#define ___GFP_RECLAIMABLE 0x10u > > -#define ___GFP_HIGH 0x20u > > -#define ___GFP_IO 0x40u > > -#define ___GFP_FS 0x80u > > -#define ___GFP_ZERO 0x100u > > +#define ___GFP_DMA BIT(___GFP_DMA_BIT) > > +#define ___GFP_HIGHMEM BIT(___GFP_HIGHMEM_BIT) > > +#define ___GFP_DMA32 BIT(___GFP_DMA32_BIT) > > +#define ___GFP_MOVABLE BIT(___GFP_MOVABLE_BIT) > > +#define ___GFP_RECLAIMABLE BIT(___GFP_RECLAIMABLE_BIT) > > +#define ___GFP_HIGH BIT(___GFP_HIGH_BIT) > > +#define ___GFP_IO BIT(___GFP_IO_BIT) > > +#define ___GFP_FS BIT(___GFP_FS_BIT) > > +#define ___GFP_ZERO BIT(___GFP_ZERO_BIT) > > /* 0x200u unused */ > > Keeping this comment here is now useless, IMHO. Until the cleanup I would prefer to have it here to denote the gap. Thanks, Suren. > > CJ > > > -#define ___GFP_DIRECT_RECLAIM 0x400u > > -#define ___GFP_KSWAPD_RECLAIM 0x800u > > -#define ___GFP_WRITE 0x1000u > > -#define ___GFP_NOWARN 0x2000u > > -#define ___GFP_RETRY_MAYFAIL 0x4000u > > -#define ___GFP_NOFAIL 0x8000u > > -#define ___GFP_NORETRY 0x10000u > > -#define ___GFP_MEMALLOC 0x20000u > > -#define ___GFP_COMP 0x40000u > > -#define ___GFP_NOMEMALLOC 0x80000u > > -#define ___GFP_HARDWALL 0x100000u > > -#define ___GFP_THISNODE 0x200000u > > -#define ___GFP_ACCOUNT 0x400000u > > -#define ___GFP_ZEROTAGS 0x800000u > > +#define ___GFP_DIRECT_RECLAIM BIT(___GFP_DIRECT_RECLAIM_BIT) > > +#define ___GFP_KSWAPD_RECLAIM BIT(___GFP_KSWAPD_RECLAIM_BIT) > > +#define ___GFP_WRITE BIT(___GFP_WRITE_BIT) > > +#define ___GFP_NOWARN BIT(___GFP_NOWARN_BIT) > > +#define ___GFP_RETRY_MAYFAIL BIT(___GFP_RETRY_MAYFAIL_BIT) > > +#define ___GFP_NOFAIL BIT(___GFP_NOFAIL_BIT) > > +#define ___GFP_NORETRY BIT(___GFP_NORETRY_BIT) > > +#define ___GFP_MEMALLOC BIT(___GFP_MEMALLOC_BIT) > > +#define ___GFP_COMP BIT(___GFP_COMP_BIT) > > +#define ___GFP_NOMEMALLOC BIT(___GFP_NOMEMALLOC_BIT) > > +#define ___GFP_HARDWALL BIT(___GFP_HARDWALL_BIT) > > +#define ___GFP_THISNODE BIT(___GFP_THISNODE_BIT) > > +#define ___GFP_ACCOUNT BIT(___GFP_ACCOUNT_BIT) > > +#define ___GFP_ZEROTAGS BIT(___GFP_ZEROTAGS_BIT) > > #ifdef CONFIG_KASAN_HW_TAGS > > -#define ___GFP_SKIP_ZERO 0x1000000u > > -#define ___GFP_SKIP_KASAN 0x2000000u > > +#define ___GFP_SKIP_ZERO BIT(___GFP_SKIP_ZERO_BIT) > > +#define ___GFP_SKIP_KASAN BIT(___GFP_SKIP_KASAN_BIT) > > #else > > #define ___GFP_SKIP_ZERO 0 > > #define ___GFP_SKIP_KASAN 0 > > #endif > > #ifdef CONFIG_LOCKDEP > > -#define ___GFP_NOLOCKDEP 0x4000000u > > +#define ___GFP_NOLOCKDEP BIT(___GFP_NOLOCKDEP_BIT) > > #else > > #define ___GFP_NOLOCKDEP 0 > > #endif > > -/* If the above are modified, __GFP_BITS_SHIFT may need updating */ > > > > /* > > * Physical address zone modifiers (see linux/mmzone.h - low four bits) > > @@ -249,7 +283,7 @@ typedef unsigned int __bitwise gfp_t; > > #define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP) > > > > /* Room for N __GFP_FOO bits */ > > -#define __GFP_BITS_SHIFT (26 + IS_ENABLED(CONFIG_LOCKDEP)) > > +#define __GFP_BITS_SHIFT ___GFP_LAST_BIT > > #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1)) > > > > /** > > > > base-commit: 603c04e27c3e9891ce7afa5cd6b496bfacff4206 >
