[PATCH v2] mm/cma: report base address of single range correctly

[PATCH v2] mm/cma: report base address of single range correctly

[Frank van der Linden]

The cma_declare_contiguous_nid code was refactored by
commit c009da4258f9 ("mm, cma: support multiple contiguous
ranges, if requested"), so that it could use an internal
function to attempt a single range area first, and then
try a multi-range one.

However, that meant that the actual base address used for
the !fixed case (base == 0) wasn't available one level up
to be printed in the informational message, and it would
always end up printing a base address of 0 in the boot
message.

Make the internal function take a phys_addr_t pointer to
the base address, so that the value is available to the
caller.

Fixes: c009da4258f9 ("mm, cma: support multiple contiguous ranges, if requested")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Closes: https://lore.kernel.org/linux-mm/CAMuHMdVWviQ7O9yBFE3f=ev0eVb1CnsQvR6SKtEROBbM6z7g3w@mail.gmail.com/
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Frank van der Linden <fvdl@google.com>
---
 mm/cma.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/mm/cma.c b/mm/cma.c
index b06d5fe73399..15632939f20a 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -35,7 +35,7 @@
 struct cma cma_areas[MAX_CMA_AREAS];
 unsigned int cma_area_count;
 
-static int __init __cma_declare_contiguous_nid(phys_addr_t base,
+static int __init __cma_declare_contiguous_nid(phys_addr_t *basep,
 			phys_addr_t size, phys_addr_t limit,
 			phys_addr_t alignment, unsigned int order_per_bit,
 			bool fixed, const char *name, struct cma **res_cma,
@@ -370,7 +370,7 @@ int __init cma_declare_contiguous_multi(phys_addr_t total_size,
 			phys_addr_t align, unsigned int order_per_bit,
 			const char *name, struct cma **res_cma, int nid)
 {
-	phys_addr_t start, end;
+	phys_addr_t start = 0, end;
 	phys_addr_t size, sizesum, sizeleft;
 	struct cma_init_memrange *mrp, *mlp, *failed;
 	struct cma_memrange *cmrp;
@@ -384,7 +384,7 @@ int __init cma_declare_contiguous_multi(phys_addr_t total_size,
 	/*
 	 * First, try it the normal way, producing just one range.
 	 */
-	ret = __cma_declare_contiguous_nid(0, total_size, 0, align,
+	ret = __cma_declare_contiguous_nid(&start, total_size, 0, align,
 			order_per_bit, false, name, res_cma, nid);
 	if (ret != -ENOMEM)
 		goto out;
@@ -580,7 +580,7 @@ int __init cma_declare_contiguous_nid(phys_addr_t base,
 {
 	int ret;
 
-	ret = __cma_declare_contiguous_nid(base, size, limit, alignment,
+	ret = __cma_declare_contiguous_nid(&base, size, limit, alignment,
 			order_per_bit, fixed, name, res_cma, nid);
 	if (ret != 0)
 		pr_err("Failed to reserve %ld MiB\n",
@@ -592,14 +592,14 @@ int __init cma_declare_contiguous_nid(phys_addr_t base,
 	return ret;
 }
 
-static int __init __cma_declare_contiguous_nid(phys_addr_t base,
+static int __init __cma_declare_contiguous_nid(phys_addr_t *basep,
 			phys_addr_t size, phys_addr_t limit,
 			phys_addr_t alignment, unsigned int order_per_bit,
 			bool fixed, const char *name, struct cma **res_cma,
 			int nid)
 {
 	phys_addr_t memblock_end = memblock_end_of_DRAM();
-	phys_addr_t highmem_start;
+	phys_addr_t highmem_start, base = *basep;
 	int ret;
 
 	/*
@@ -722,12 +722,15 @@ static int __init __cma_declare_contiguous_nid(phys_addr_t base,
 	}
 
 	ret = cma_init_reserved_mem(base, size, order_per_bit, name, res_cma);
-	if (ret)
+	if (ret) {
 		memblock_phys_free(base, size);
+		return ret;
+	}
 
 	(*res_cma)->nid = nid;
+	*basep = base;
 
-	return ret;
+	return 0;
 }
 
 static void cma_debug_show_areas(struct cma *cma)
-- 
2.49.0.504.g3bcea36a83-goog

Re: [PATCH v2] mm/cma: report base address of single range correctly

[Andrew Morton]

On Tue,  8 Apr 2025 16:40:00 +0000 Frank van der Linden <fvdl@google.com> wrote:

> The cma_declare_contiguous_nid code was refactored by
> commit c009da4258f9 ("mm, cma: support multiple contiguous
> ranges, if requested"), so that it could use an internal
> function to attempt a single range area first, and then
> try a multi-range one.
> 
> However, that meant that the actual base address used for
> the !fixed case (base == 0) wasn't available one level up
> to be printed in the informational message, and it would
> always end up printing a base address of 0 in the boot
> message.
> 
> Make the internal function take a phys_addr_t pointer to
> the base address, so that the value is available to the
> caller.

Changes from v1 are:

--- a/mm/cma.c~mm-cma-report-base-address-of-single-range-correctly-v2
+++ a/mm/cma.c
@@ -722,14 +722,15 @@ static int __init __cma_declare_contiguo
 	}
 
 	ret = cma_init_reserved_mem(base, size, order_per_bit, name, res_cma);
-	if (ret)
+	if (ret) {
 		memblock_phys_free(base, size);
-	else {
-		(*res_cma)->nid = nid;
-		*basep = base;
+		return ret;
 	}
 
-	return ret;
+	(*res_cma)->nid = nid;
+	*basep = base;
+
+	return 0;
 }
 
 static void cma_debug_show_areas(struct cma *cma)
_

Which appears to be just a little cleanup?

Re: [PATCH v2] mm/cma: report base address of single range correctly

[Frank van der Linden]

On Tue, Apr 8, 2025 at 2:03 PM Andrew Morton <akpm@linux-foundation.org> wrote:
>
> On Tue,  8 Apr 2025 16:40:00 +0000 Frank van der Linden <fvdl@google.com> wrote:
>
> > The cma_declare_contiguous_nid code was refactored by
> > commit c009da4258f9 ("mm, cma: support multiple contiguous
> > ranges, if requested"), so that it could use an internal
> > function to attempt a single range area first, and then
> > try a multi-range one.
> >
> > However, that meant that the actual base address used for
> > the !fixed case (base == 0) wasn't available one level up
> > to be printed in the informational message, and it would
> > always end up printing a base address of 0 in the boot
> > message.
> >
> > Make the internal function take a phys_addr_t pointer to
> > the base address, so that the value is available to the
> > caller.
>
> Changes from v1 are:
>
> --- a/mm/cma.c~mm-cma-report-base-address-of-single-range-correctly-v2
> +++ a/mm/cma.c
> @@ -722,14 +722,15 @@ static int __init __cma_declare_contiguo
>         }
>
>         ret = cma_init_reserved_mem(base, size, order_per_bit, name, res_cma);
> -       if (ret)
> +       if (ret) {
>                 memblock_phys_free(base, size);
> -       else {
> -               (*res_cma)->nid = nid;
> -               *basep = base;
> +               return ret;
>         }
>
> -       return ret;
> +       (*res_cma)->nid = nid;
> +       *basep = base;
> +
> +       return 0;
>  }
>
>  static void cma_debug_show_areas(struct cma *cma)
> _
>
> Which appears to be just a little cleanup?

Correct, it just fixes a style nit that Geert pointed out.

- Frank

Re: [PATCH v2] mm/cma: report base address of single range correctly

[Geert Uytterhoeven]

Hi Frank,

On Tue, 8 Apr 2025 at 18:40, Frank van der Linden <fvdl@google.com> wrote:
> The cma_declare_contiguous_nid code was refactored by
> commit c009da4258f9 ("mm, cma: support multiple contiguous
> ranges, if requested"), so that it could use an internal
> function to attempt a single range area first, and then
> try a multi-range one.
>
> However, that meant that the actual base address used for
> the !fixed case (base == 0) wasn't available one level up
> to be printed in the informational message, and it would
> always end up printing a base address of 0 in the boot
> message.
>
> Make the internal function take a phys_addr_t pointer to
> the base address, so that the value is available to the
> caller.
>
> Fixes: c009da4258f9 ("mm, cma: support multiple contiguous ranges, if requested")
> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
> Closes: https://lore.kernel.org/linux-mm/CAMuHMdVWviQ7O9yBFE3f=ev0eVb1CnsQvR6SKtEROBbM6z7g3w@mail.gmail.com/

Thanks for your patch, which is now commit 60580e0bd587b1df ("mm/cma:
report base address of single range correctly") upstream.

> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>

FTR, the email addres in this tag does not match the tag given in
https://lore.kernel.org/all/CAMuHMdUeGjbOx-aJTvwOVBWdUFmY7wU-p3mKaCbEzQ4PbJDqNg@mail.gmail.com

> Signed-off-by: Frank van der Linden <fvdl@google.com>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds