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 <[email protected]>
Signed-off-by: Suren Baghdasaryan <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Reviewed-by: Pasha Tatashin <[email protected]>
Acked-by: Michal Hocko <[email protected]>
---
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/[email protected]/
[2] https://lore.kernel.org/all/[email protected]/
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 */
+ ___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
+};
+
/* 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 */
-#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
--
2.44.0.rc0.258.g7320e95886-goog
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 <[email protected]>
> Signed-off-by: Suren Baghdasaryan <[email protected]>
> Reviewed-by: Kees Cook <[email protected]>
> Reviewed-by: Pasha Tatashin <[email protected]>
> Acked-by: Michal Hocko <[email protected]>
> ---
> 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/[email protected]/
> [2] https://lore.kernel.org/all/[email protected]/
>
> 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?
> + ___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");
(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.
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
On Sat, Feb 24, 2024 at 7:03 AM Christophe JAILLET
<[email protected]> 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 <[email protected]>
> > Signed-off-by: Suren Baghdasaryan <[email protected]>
> > Reviewed-by: Kees Cook <[email protected]>
> > Reviewed-by: Pasha Tatashin <[email protected]>
> > Acked-by: Michal Hocko <[email protected]>
> > ---
> > 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/[email protected]/
> > [2] https://lore.kernel.org/all/[email protected]/
> >
> > 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
>
On Sun 25-02-24 01:12:46, Suren Baghdasaryan wrote:
> On Sat, Feb 24, 2024 at 7:03 AM Christophe JAILLET
> <[email protected]> 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 <[email protected]>
> > > Signed-off-by: Suren Baghdasaryan <[email protected]>
> > > Reviewed-by: Kees Cook <[email protected]>
> > > Reviewed-by: Pasha Tatashin <[email protected]>
> > > Acked-by: Michal Hocko <[email protected]>
> > > ---
> > > 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/[email protected]/
> > > [2] https://lore.kernel.org/all/[email protected]/
> > >
> > > 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.
Agreed!
> > > + ___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?
Would that check add much? We currently cannot use the full width of the
gfp_t because radix tree code needs to fit also its own tag into the
same word (see radix_tree_init). If the radix tree constrain is lifted
then we should add something like the above.
--
Michal Hocko
SUSE Labs
On Mon, Feb 26, 2024 at 12:43 AM Michal Hocko <[email protected]> wrote:
>
> On Sun 25-02-24 01:12:46, Suren Baghdasaryan wrote:
> > On Sat, Feb 24, 2024 at 7:03 AM Christophe JAILLET
> > <[email protected]> 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 <[email protected]>
> > > > Signed-off-by: Suren Baghdasaryan <[email protected]>
> > > > Reviewed-by: Kees Cook <[email protected]>
> > > > Reviewed-by: Pasha Tatashin <[email protected]>
> > > > Acked-by: Michal Hocko <[email protected]>
> > > > ---
> > > > 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/[email protected]/
> > > > [2] https://lore.kernel.org/all/[email protected]/
> > > >
> > > > 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.
>
> Agreed!
>
> > > > + ___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?
>
> Would that check add much? We currently cannot use the full width of the
> gfp_t because radix tree code needs to fit also its own tag into the
> same word (see radix_tree_init). If the radix tree constrain is lifted
> then we should add something like the above.
Ah, good point. That check in radix_tree_init() is already more strict
than this one. Looks like we are covered.
Thanks,
Suren.
> --
> Michal Hocko
> SUSE Labs