[PATCH] mm/early_ioremap: Print the starting physical address in __early_ioremap()

[PATCH] mm/early_ioremap: Print the starting physical address in __early_ioremap()

[Hou Wenlong]

The debug WARN() printing occurs after the while loop, so the
'phys_addr' reflects the last physical address rather than the actual
starting physical address, which is not useful for debugging. To
simplify, the WARN() statement could be moved up before the loop instead
of introducing a new variable to record the original 'phys_addr' value.
Additionally, swap the print order of 'slot_virt[slot]' and 'offset', as
this will enhance output readability.

Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
---
 mm/early_ioremap.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/mm/early_ioremap.c b/mm/early_ioremap.c
index ff35b84a7b50..3fdde074c9da 100644
--- a/mm/early_ioremap.c
+++ b/mm/early_ioremap.c
@@ -139,6 +139,9 @@ __early_ioremap(resource_size_t phys_addr, unsigned long size, pgprot_t prot)
 	if (WARN_ON(nrpages > NR_FIX_BTMAPS))
 		return NULL;
 
+	WARN(early_ioremap_debug, "%s(%pa, %08lx) [%d] => %08lx + %08lx\n",
+	     __func__, &phys_addr, size, slot, slot_virt[slot], offset);
+
 	/*
 	 * Ok, go for it..
 	 */
@@ -152,8 +155,6 @@ __early_ioremap(resource_size_t phys_addr, unsigned long size, pgprot_t prot)
 		--idx;
 		--nrpages;
 	}
-	WARN(early_ioremap_debug, "%s(%pa, %08lx) [%d] => %08lx + %08lx\n",
-	     __func__, &phys_addr, size, slot, offset, slot_virt[slot]);
 
 	prev_map[slot] = (void __iomem *)(offset + slot_virt[slot]);
 	return prev_map[slot];
-- 
2.31.1

Re: [PATCH] mm/early_ioremap: Print the starting physical address in __early_ioremap()

[Andrew Morton]

On Fri,  9 Jan 2026 21:31:51 +0800 Hou Wenlong <houwenlong.hwl@antgroup.com> wrote:

> The debug WARN() printing occurs after the while loop, so the
> 'phys_addr' reflects the last physical address rather than the actual
> starting physical address, which is not useful for debugging. To
> simplify, the WARN() statement could be moved up before the loop instead
> of introducing a new variable to record the original 'phys_addr' value.
> Additionally, swap the print order of 'slot_virt[slot]' and 'offset', as
> this will enhance output readability.
> 

yep, thanks.

> --- a/mm/early_ioremap.c
> +++ b/mm/early_ioremap.c
> @@ -139,6 +139,9 @@ __early_ioremap(resource_size_t phys_addr, unsigned long size, pgprot_t prot)
>  	if (WARN_ON(nrpages > NR_FIX_BTMAPS))
>  		return NULL;
>  
> +	WARN(early_ioremap_debug, "%s(%pa, %08lx) [%d] => %08lx + %08lx\n",
> +	     __func__, &phys_addr, size, slot, slot_virt[slot], offset);
> +
>  	/*
>  	 * Ok, go for it..
>  	 */
> @@ -152,8 +155,6 @@ __early_ioremap(resource_size_t phys_addr, unsigned long size, pgprot_t prot)
>  		--idx;
>  		--nrpages;
>  	}
> -	WARN(early_ioremap_debug, "%s(%pa, %08lx) [%d] => %08lx + %08lx\n",
> -	     __func__, &phys_addr, size, slot, offset, slot_virt[slot]);

It's strange that this code uses WARN when nothing is wrong.  The rest
of the function uses WARN appropriately.  But that's off-topic!

Reviewed-by: Andrew Morton <akpm@linux-foundation.org>