linux-kernel - Re: [PATCH V3 01/27] kfifo: add kfifo_alloc

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Message-ID: <aRm8sDRh2UEjpYH_@fedora>
Date: Sun, 16 Nov 2025 19:59:44 +0800
From: Ming Lei <ming.lei@...hat.com>
To: Caleb Sander Mateos <csander@...estorage.com>
Cc: Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org,
	Uday Shankar <ushankar@...estorage.com>,
	Stefani Seibold <stefani@...bold.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3 01/27] kfifo: add kfifo_alloc_node() helper for NUMA
 awareness

On Fri, Nov 14, 2025 at 08:14:29PM -0800, Caleb Sander Mateos wrote:
> On Wed, Nov 12, 2025 at 1:38 AM Ming Lei <ming.lei@...hat.com> wrote:
> >
> > Add __kfifo_alloc_node() by refactoring and reusing __kfifo_alloc(),
> > and define kfifo_alloc_node() macro to support NUMA-aware memory
> > allocation.
> >
> > The new __kfifo_alloc_node() function accepts a NUMA node parameter
> > and uses kmalloc_array_node() instead of kmalloc_array() for
> > node-specific allocation. The existing __kfifo_alloc() now calls
> > __kfifo_alloc_node() with NUMA_NO_NODE to maintain backward
> > compatibility.
> >
> > This enables users to allocate kfifo buffers on specific NUMA nodes,
> > which is important for performance in NUMA systems where the kfifo
> > will be primarily accessed by threads running on specific nodes.
> >
> > Cc: Stefani Seibold <stefani@...bold.net>
> > Cc: Andrew Morton <akpm@...ux-foundation.org>
> > Cc: linux-kernel@...r.kernel.org
> > Signed-off-by: Ming Lei <ming.lei@...hat.com>
> > ---
> >  include/linux/kfifo.h | 27 +++++++++++++++++++++++++++
> >  lib/kfifo.c           | 13 ++++++++++---
> >  2 files changed, 37 insertions(+), 3 deletions(-)
> >
> > diff --git a/include/linux/kfifo.h b/include/linux/kfifo.h
> > index fd743d4c4b4b..61d1fe014a6c 100644
> > --- a/include/linux/kfifo.h
> > +++ b/include/linux/kfifo.h
> > @@ -369,6 +369,30 @@ __kfifo_int_must_check_helper( \
> >  }) \
> >  )
> >
> > +/**
> > + * kfifo_alloc_node - dynamically allocates a new fifo buffer on a NUMA node
> > + * @fifo: pointer to the fifo
> > + * @size: the number of elements in the fifo, this must be a power of 2
> > + * @gfp_mask: get_free_pages mask, passed to kmalloc()
> > + * @node: NUMA node to allocate memory on
> > + *
> > + * This macro dynamically allocates a new fifo buffer with NUMA node awareness.
> > + *
> > + * The number of elements will be rounded-up to a power of 2.
> > + * The fifo will be release with kfifo_free().
> > + * Return 0 if no error, otherwise an error code.
> > + */
> > +#define kfifo_alloc_node(fifo, size, gfp_mask, node) \
> > +__kfifo_int_must_check_helper( \
> > +({ \
> > +       typeof((fifo) + 1) __tmp = (fifo); \
> > +       struct __kfifo *__kfifo = &__tmp->kfifo; \
> > +       __is_kfifo_ptr(__tmp) ? \
> > +       __kfifo_alloc_node(__kfifo, size, sizeof(*__tmp->type), gfp_mask, node) : \
> > +       -EINVAL; \
> > +}) \
> > +)
> > +
> >  /**
> >   * kfifo_free - frees the fifo
> >   * @fifo: the fifo to be freed
> > @@ -902,6 +926,9 @@ __kfifo_uint_must_check_helper( \
> >  extern int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
> >         size_t esize, gfp_t gfp_mask);
> >
> > +extern int __kfifo_alloc_node(struct __kfifo *fifo, unsigned int size,
> > +       size_t esize, gfp_t gfp_mask, int node);
> > +
> >  extern void __kfifo_free(struct __kfifo *fifo);
> >
> >  extern int __kfifo_init(struct __kfifo *fifo, void *buffer,
> > diff --git a/lib/kfifo.c b/lib/kfifo.c
> > index a8b2eed90599..195cf0feecc2 100644
> > --- a/lib/kfifo.c
> > +++ b/lib/kfifo.c
> > @@ -22,8 +22,8 @@ static inline unsigned int kfifo_unused(struct __kfifo *fifo)
> >         return (fifo->mask + 1) - (fifo->in - fifo->out);
> >  }
> >
> > -int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
> > -               size_t esize, gfp_t gfp_mask)
> > +int __kfifo_alloc_node(struct __kfifo *fifo, unsigned int size,
> > +               size_t esize, gfp_t gfp_mask, int node)
> >  {
> >         /*
> >          * round up to the next power of 2, since our 'let the indices
> > @@ -41,7 +41,7 @@ int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
> >                 return -EINVAL;
> >         }
> >
> > -       fifo->data = kmalloc_array(esize, size, gfp_mask);
> > +       fifo->data = kmalloc_array_node(esize, size, gfp_mask, node);
> >
> >         if (!fifo->data) {
> >                 fifo->mask = 0;
> > @@ -51,6 +51,13 @@ int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
> >
> >         return 0;
> >  }
> > +EXPORT_SYMBOL(__kfifo_alloc_node);
> > +
> > +int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
> > +               size_t esize, gfp_t gfp_mask)
> > +{
> > +       return __kfifo_alloc_node(fifo, size, esize, gfp_mask, NUMA_NO_NODE);
> > +}
> >  EXPORT_SYMBOL(__kfifo_alloc);
> 
> Is it worth keeping __kfifo_alloc() as an extern function? Seems like
> it would make the executable smaller to turn __kfifo_alloc() into a
> static inline function that just defers to __kfifo_alloc_node().

OK, will convert to inline __kfifo_alloc() in next version.


Thanks,
Ming