From: Simon Schuster Date: Thu, 21 Aug 2025 10:37:07 +0000 (+0200) Subject: nios2: ensure that memblock.current_limit is set when setting pfn limits X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a20b83cf45be2057f3d073506779e52c7fa17f94;p=thirdparty%2Fkernel%2Fstable.git nios2: ensure that memblock.current_limit is set when setting pfn limits On nios2, with CONFIG_FLATMEM set, the kernel relies on memblock_get_current_limit() to determine the limits of mem_map, in particular for max_low_pfn. Unfortunately, memblock.current_limit is only default initialized to MEMBLOCK_ALLOC_ANYWHERE at this point of the bootup, potentially leading to situations where max_low_pfn can erroneously exceed the value of max_pfn and, thus, the valid range of available DRAM. This can in turn cause kernel-level paging failures, e.g.: [ 76.900000] Unable to handle kernel paging request at virtual address 20303000 [ 76.900000] ea = c0080890, ra = c000462c, cause = 14 [ 76.900000] Kernel panic - not syncing: Oops [ 76.900000] ---[ end Kernel panic - not syncing: Oops ]--- This patch fixes this by pre-calculating memblock.current_limit based on the upper limits of the available memory ranges via adjust_lowmem_bounds, a simplified version of the equivalent implementation within the arm architecture. Signed-off-by: Simon Schuster Signed-off-by: Andreas Oetken Signed-off-by: Dinh Nguyen --- diff --git a/arch/nios2/kernel/setup.c b/arch/nios2/kernel/setup.c index 2a40150142c36..f43f01c4ab934 100644 --- a/arch/nios2/kernel/setup.c +++ b/arch/nios2/kernel/setup.c @@ -142,6 +142,20 @@ static void __init find_limits(unsigned long *min, unsigned long *max_low, *max_high = PFN_DOWN(memblock_end_of_DRAM()); } +static void __init adjust_lowmem_bounds(void) +{ + phys_addr_t block_start, block_end; + u64 i; + phys_addr_t memblock_limit = 0; + + for_each_mem_range(i, &block_start, &block_end) { + if (block_end > memblock_limit) + memblock_limit = block_end; + } + + memblock_set_current_limit(memblock_limit); +} + void __init setup_arch(char **cmdline_p) { console_verbose(); @@ -157,6 +171,7 @@ void __init setup_arch(char **cmdline_p) /* Keep a copy of command line */ *cmdline_p = boot_command_line; + adjust_lowmem_bounds(); find_limits(&min_low_pfn, &max_low_pfn, &max_pfn); memblock_reserve(__pa_symbol(_stext), _end - _stext);