On Mon, 1 May 2023 09:54:19 -0700 Suren Baghdasaryan <surenb@xxxxxxxxxx> wrote: > Introduce __GFP_NO_OBJ_EXT flag in order to prevent recursive allocations > when allocating slabobj_ext on a slab. > > Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx> > --- > include/linux/gfp_types.h | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/include/linux/gfp_types.h b/include/linux/gfp_types.h > index 6583a58670c5..aab1959130f9 100644 > --- a/include/linux/gfp_types.h > +++ b/include/linux/gfp_types.h > @@ -53,8 +53,13 @@ typedef unsigned int __bitwise gfp_t; > #define ___GFP_SKIP_ZERO 0 > #define ___GFP_SKIP_KASAN 0 > #endif > +#ifdef CONFIG_SLAB_OBJ_EXT > +#define ___GFP_NO_OBJ_EXT 0x4000000u > +#else > +#define ___GFP_NO_OBJ_EXT 0 > +#endif > #ifdef CONFIG_LOCKDEP > -#define ___GFP_NOLOCKDEP 0x4000000u > +#define ___GFP_NOLOCKDEP 0x8000000u So now we have two flags that depend on config options, but the first one is always allocated in fact. I wonder if you could use an enum to let the compiler allocate bits. Something similar to what Muchun Song did with section flags. See commit ed7802dd48f7a507213cbb95bb4c6f1fe134eb5d for reference. > #else > #define ___GFP_NOLOCKDEP 0 > #endif > @@ -99,12 +104,15 @@ typedef unsigned int __bitwise gfp_t; > * node with no fallbacks or placement policy enforcements. > * > * %__GFP_ACCOUNT causes the allocation to be accounted to kmemcg. > + * > + * %__GFP_NO_OBJ_EXT causes slab allocation to have no object > extension. */ > #define __GFP_RECLAIMABLE ((__force gfp_t)___GFP_RECLAIMABLE) > #define __GFP_WRITE ((__force gfp_t)___GFP_WRITE) > #define __GFP_HARDWALL ((__force gfp_t)___GFP_HARDWALL) > #define __GFP_THISNODE ((__force gfp_t)___GFP_THISNODE) > #define __GFP_ACCOUNT ((__force gfp_t)___GFP_ACCOUNT) > +#define __GFP_NO_OBJ_EXT ((__force gfp_t)___GFP_NO_OBJ_EXT) > > /** > * DOC: Watermark modifiers > @@ -249,7 +257,7 @@ 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 (27 + IS_ENABLED(CONFIG_LOCKDEP)) If the above suggestion is implemented, this could be changed to something like __GFP_LAST_BIT (the enum's last identifier). Petr T
