On Thu, Mar 20, 2025 at 10:39:31AM -0700, Suren Baghdasaryan wrote:
> This patch introduces a new "guarantee" property for shared-dma-pool.
> With this property, admin can create specific memory pool as
> GCMA-based CMA if they care about allocation success rate and latency.
> The downside of GCMA is that it can host only clean file-backed pages
> since it's using cleancache as its secondary user.
>
> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
> Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
> ---
> arch/powerpc/kernel/fadump.c | 2 +-
> include/linux/cma.h | 2 +-
> kernel/dma/contiguous.c | 11 ++++++++++-
> mm/cma.c | 33 ++++++++++++++++++++++++++-------
> mm/cma.h | 1 +
> mm/cma_sysfs.c | 10 ++++++++++
> 6 files changed, 49 insertions(+), 10 deletions(-)
>
> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
> index 4b371c738213..4eb7be0cdcdb 100644
> --- a/arch/powerpc/kernel/fadump.c
> +++ b/arch/powerpc/kernel/fadump.c
> @@ -111,7 +111,7 @@ void __init fadump_cma_init(void)
> return;
> }
>
> - rc = cma_init_reserved_mem(base, size, 0, "fadump_cma", &fadump_cma);
> + rc = cma_init_reserved_mem(base, size, 0, "fadump_cma", &fadump_cma, false);
> if (rc) {
> pr_err("Failed to init cma area for firmware-assisted dump,%d\n", rc);
> /*
> diff --git a/include/linux/cma.h b/include/linux/cma.h
> index 62d9c1cf6326..3207db979e94 100644
> --- a/include/linux/cma.h
> +++ b/include/linux/cma.h
> @@ -46,7 +46,7 @@ extern int __init cma_declare_contiguous_multi(phys_addr_t size,
> extern int cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
> unsigned int order_per_bit,
> const char *name,
> - struct cma **res_cma);
> + struct cma **res_cma, bool gcma);
> extern struct page *cma_alloc(struct cma *cma, unsigned long count, unsigned int align,
> bool no_warn);
> extern bool cma_pages_valid(struct cma *cma, const struct page *pages, unsigned long count);
> diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
> index 055da410ac71..a68b3123438c 100644
> --- a/kernel/dma/contiguous.c
> +++ b/kernel/dma/contiguous.c
> @@ -459,6 +459,7 @@ static int __init rmem_cma_setup(struct reserved_mem *rmem)
> unsigned long node = rmem->fdt_node;
> bool default_cma = of_get_flat_dt_prop(node, "linux,cma-default", NULL);
> struct cma *cma;
> + bool gcma;
> int err;
>
> if (size_cmdline != -1 && default_cma) {
> @@ -476,7 +477,15 @@ static int __init rmem_cma_setup(struct reserved_mem *rmem)
> return -EINVAL;
> }
>
> - err = cma_init_reserved_mem(rmem->base, rmem->size, 0, rmem->name, &cma);
> + gcma = !!of_get_flat_dt_prop(node, "guarantee", NULL);
When this (or if I guess) this goes !RFC, you will need to document this
new property that you're adding.
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