From f171b55f1441294344b86edfeaa575ea9673fd23 Mon Sep 17 00:00:00 2001 From: "Mike Rapoport (Microsoft)" Date: Wed, 31 Dec 2025 12:57:01 +0200 Subject: [PATCH] mips: fix HIGHMEM initialization Commit 6faea3422e3b ("arch, mm: streamline HIGHMEM freeing") overzealously removed mem_init_free_highmem() function that beside freeing high memory pages checked for CPU support for high memory as a prerequisite. Partially restore mem_init_free_highmem() with a new highmem_init() name and make it discard high memory in case there is no CPU support for it. Link: https://lkml.kernel.org/r/20251231105701.519711-1-rppt@kernel.org Fixes: 6faea3422e3b ("arch, mm: streamline HIGHMEM freeing") Signed-off-by: Mike Rapoport (Microsoft) Reported-by: Markus Stockhausen Cc: Chris Packham Cc: Hauke Mehrtens Cc: Jonas Jelonek Cc: Thomas Bogendoerfer Cc: Thomas Gleinxer Signed-off-by: Andrew Morton --- arch/mips/mm/init.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c index a673d3d68254..8986048f9b11 100644 --- a/arch/mips/mm/init.c +++ b/arch/mips/mm/init.c @@ -425,6 +425,28 @@ void __init paging_init(void) static struct kcore_list kcore_kseg0; #endif +static inline void __init highmem_init(void) +{ +#ifdef CONFIG_HIGHMEM + unsigned long tmp; + + /* + * If CPU cannot support HIGHMEM discard the memory above highstart_pfn + */ + if (cpu_has_dc_aliases) { + memblock_remove(PFN_PHYS(highstart_pfn), -1); + return; + } + + for (tmp = highstart_pfn; tmp < highend_pfn; tmp++) { + struct page *page = pfn_to_page(tmp); + + if (!memblock_is_memory(PFN_PHYS(tmp))) + SetPageReserved(page); + } +#endif +} + void __init arch_mm_preinit(void) { /* @@ -435,6 +457,7 @@ void __init arch_mm_preinit(void) maar_init(); setup_zero_pages(); /* Setup zeroed pages. */ + highmem_init(); #ifdef CONFIG_64BIT if ((unsigned long) &_text > (unsigned long) CKSEG0) -- 2.47.3