Re: [PATCH v2 11/16] mm/slab: allow kmem_cache_alloc_bulk() with any gfp flags

[Suren Baghdasaryan]

On Fri, Jun 12, 2026 at 3:05 AM Vlastimil Babka (SUSE)
<vbabka@xxxxxxxxxx> wrote:
>
> On 6/12/26 05:21, Hao Li wrote:
> > On Wed, Jun 10, 2026 at 05:40:13PM +0200, Vlastimil Babka (SUSE) wrote:
> >> The last user of gfpflags_allow_spinning() in slab is
> >> alloc_from_pcs_bulk(), which is only called from
> >> kmem_cache_alloc_bulk().
> >>
> >> It turns out that gfpflags_allow_spinning() is not necessary, because
> >> kmem_cache_alloc_bulk() is only expected to be called from context that
> >> does allow spinning, so simply replace it with 'true'.
> >>
> >> With that, we can remove the "@flags must allow spinning" part of the
> >> kernel doc, as there is no more connection to the gfp flags in the slab
> >> implementation.
> >>
> >> Also remove a comment in alloc_slab_obj_exts() because there should be
> >> no more false positives possible due to gfp_allowed_mask during early
> >> boot.
> >>
> >> Signed-off-by: Vlastimil Babka (SUSE) <vbabka@xxxxxxxxxx>
> >> ---
> >>  mm/slub.c | 11 ++---------
> >>  1 file changed, 2 insertions(+), 9 deletions(-)
> >>
> >> diff --git a/mm/slub.c b/mm/slub.c
> >> index 0b9974bfcb24..ef457e07db83 100644
> >> --- a/mm/slub.c
> >> +++ b/mm/slub.c
> >> @@ -2171,12 +2171,6 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
> >>
> >>      sz = obj_exts_alloc_size(s, slab, gfp);
> >>
> >> -    /*
> >> -     * Note that allow_spin may be false during early boot and its
> >> -     * restricted GFP_BOOT_MASK. Due to kmalloc_nolock() only supporting
> >> -     * architectures with cmpxchg16b, early obj_exts will be missing for
> >> -     * very early allocations on those.
> >> -     */
> >>      if (unlikely(!allow_spin))
> >>              vec = kmalloc_nolock(sz, __GFP_ZERO | __GFP_NO_OBJ_EXT,
> >>                                   slab_nid(slab));
> >> @@ -4867,7 +4861,7 @@ unsigned int alloc_from_pcs_bulk(struct kmem_cache *s, gfp_t gfp, size_t size,
> >>              }
> >>
> >>              full = barn_replace_empty_sheaf(barn, pcs->main,
> >> -                                            gfpflags_allow_spinning(gfp));
> >> +                                            /* allow_spin = */ true);
> >
> > we can remove the `gfp` arg as this function no longer use it.
>
> True, done!

I see it fixed in
https://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab.git/log/?h=slab/for-next,
so

Reviewed-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>

>