linux-kernel - [PATCH mm-new] mm/early_ioremap: Clean up the use of WARN() for debugging

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Message-Id: <d4470531ce0c03fd80f9a1be7e8d8ae1bc60fcd1.1768220636.git.houwenlong.hwl@antgroup.com>
Date: Mon, 12 Jan 2026 20:24:29 +0800
From: Hou Wenlong <houwenlong.hwl@...group.com>
To: linux-kernel@...r.kernel.org
Cc: Hou Wenlong <houwenlong.hwl@...group.com>,
	Mike Rapoport <rppt@...nel.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: [PATCH mm-new] mm/early_ioremap: Clean up the use of WARN() for debugging

Using WARN() for debugging is strange when nothing is wrong, so replace
WARN(early_ioremap_debug) with pr_warn() + dump_stack().

Suggested-by: Mike Rapoport <rppt@...nel.org>
Signed-off-by: Hou Wenlong <houwenlong.hwl@...group.com>
---
 mm/early_ioremap.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/mm/early_ioremap.c b/mm/early_ioremap.c
index 3fdde074c9da..96c29b9dc85d 100644
--- a/mm/early_ioremap.c
+++ b/mm/early_ioremap.c
@@ -30,6 +30,14 @@ static int __init early_ioremap_debug_setup(char *str)
 }
 early_param("early_ioremap_debug", early_ioremap_debug_setup);
 
+#define early_ioremap_dbg(fmt, args...)			\
+	do {						\
+		if (unlikely(early_ioremap_debug)) {	\
+			pr_warn(fmt, ##args);		\
+			dump_stack();			\
+		}					\
+	} while (0)
+
 static int after_paging_init __initdata;
 
 pgprot_t __init __weak early_memremap_pgprot_adjust(resource_size_t phys_addr,
@@ -139,8 +147,8 @@ __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);
+	early_ioremap_dbg("%s(%pa, %08lx) [%d] => %08lx + %08lx\n",
+			  __func__, &phys_addr, size, slot, slot_virt[slot], offset);
 
 	/*
 	 * Ok, go for it..
@@ -185,8 +193,7 @@ void __init early_iounmap(void __iomem *addr, unsigned long size)
 		  __func__, addr, size, slot, prev_size[slot]))
 		return;
 
-	WARN(early_ioremap_debug, "%s(%p, %08lx) [%d]\n",
-	      __func__, addr, size, slot);
+	early_ioremap_dbg("%s(%p, %08lx) [%d]\n", __func__, addr, size, slot);
 
 	virt_addr = (unsigned long)addr;
 	if (WARN_ON(virt_addr < fix_to_virt(FIX_BTMAP_BEGIN)))

base-commit: ab3d40bdac831c67e130fda12f3011505556500f
-- 
2.31.1