Re: [PATCH v4 7/7] mm/mm_init: Use for_each_valid_pfn() in init_unavailable_range()

[Andrew Morton]

On Fri, 25 Apr 2025 17:11:10 +0100 Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx> wrote:

> Andrew - can we drop this from mm-new? It's breaking it.

I almost did, but David seems to have a fix.

--- a/include/linux/mmzone.h~mm-mm_init-use-for_each_valid_pfn-in-init_unavailable_range-fix
+++ a/include/linux/mmzone.h
@@ -2190,10 +2190,10 @@ static inline unsigned long next_valid_p
 	/*
 	 * Either every PFN within the section (or subsection for VMEMMAP) is
 	 * valid, or none of them are. So there's no point repeating the check
-	 * for every PFN; only call first_valid_pfn() the first time, and when
-	 * crossing a (sub)section boundary (i.e. !(pfn & ~PFN_VALID_MASK)).
+	 * for every PFN; only call first_valid_pfn() again when crossing a
+	 * (sub)section boundary (i.e. !(pfn & ~PAGE_{SUB,}SECTION_MASK)).
 	 */
-	if (pfn & (IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP) ?
+	if (pfn & ~(IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP) ?
 		   PAGE_SUBSECTION_MASK : PAGE_SECTION_MASK))
 		return pfn;
 
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