linux-kernel - Re: [PATCH] mm/early_ioremap: Print the starting physical address in __early

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Message-ID: <aWNp_PRovaLO97zt@kernel.org>
Date: Sun, 11 Jan 2026 11:14:36 +0200
From: Mike Rapoport <rppt@...nel.org>
To: Hou Wenlong <houwenlong.hwl@...group.com>
Cc: linux-kernel@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>,
	David Hildenbrand <david@...nel.org>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Michal Hocko <mhocko@...e.com>, linux-mm@...ck.org
Subject: Re: [PATCH] mm/early_ioremap: Print the starting physical address in
 __early_ioremap()

On Fri, Jan 09, 2026 at 09:31:51PM +0800, Hou Wenlong 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.
> 
> Signed-off-by: Hou Wenlong <houwenlong.hwl@...group.com>

Reviewed-by: Mike Rapoport (Microsoft) <rppt@...nel.org>

> ---
>  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
> 

-- 
Sincerely yours,
Mike.