From: Aneesh Kumar K.V (IBM) Date: Wed, 3 Apr 2024 08:36:09 +0000 (+0530) Subject: powerpc/mm: Align memory_limit value specified using mem= kernel parameter X-Git-Tag: io_uring-6.10-20240523~61^2~66 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=5ca096161cdccfa328acf6704a4615528471d309;p=linux-2.6-block.git powerpc/mm: Align memory_limit value specified using mem= kernel parameter The value specified for the memory limit is used to set a restriction on memory usage. It is important to ensure that this restriction is within the linear map kernel address space range. The hash page table translation uses a 16MB page size to map the kernel linear map address space. htab_bolt_mapping() function aligns down the size of the range while mapping kernel linear address space. Since the memblock limit is enforced very early during boot, before we can detect the type of memory translation (radix vs hash), we align the memory limit value specified as a kernel parameter to 16MB. This alignment value will work for both hash and radix translations. Signed-off-by: Aneesh Kumar K.V (IBM) Acked-by: Joel Savitz Signed-off-by: Michael Ellerman Link: https://msgid.link/20240403083611.172833-1-aneesh.kumar@kernel.org --- diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c index cd8d8883de90..7451bedad1f4 100644 --- a/arch/powerpc/kernel/prom.c +++ b/arch/powerpc/kernel/prom.c @@ -846,8 +846,11 @@ void __init early_init_devtree(void *params) reserve_crashkernel(); early_reserve_mem(); - /* Ensure that total memory size is page-aligned. */ - limit = ALIGN(memory_limit ?: memblock_phys_mem_size(), PAGE_SIZE); + if (memory_limit > memblock_phys_mem_size()) + memory_limit = 0; + + /* Align down to 16 MB which is large page size with hash page translation */ + limit = ALIGN_DOWN(memory_limit ?: memblock_phys_mem_size(), SZ_16M); memblock_enforce_memory_limit(limit); #if defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_PPC_4K_PAGES) diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c index 0ef358285337..fbb68fc28ed3 100644 --- a/arch/powerpc/kernel/prom_init.c +++ b/arch/powerpc/kernel/prom_init.c @@ -817,8 +817,8 @@ static void __init early_cmdline_parse(void) opt += 4; prom_memory_limit = prom_memparse(opt, (const char **)&opt); #ifdef CONFIG_PPC64 - /* Align to 16 MB == size of ppc64 large page */ - prom_memory_limit = ALIGN(prom_memory_limit, 0x1000000); + /* Align down to 16 MB which is large page size with hash page translation */ + prom_memory_limit = ALIGN_DOWN(prom_memory_limit, SZ_16M); #endif }