On Mon, May 11, 2020 at 09:43:30AM -0700, Dave Hansen wrote:
On 5/11/20 9:37 AM, Kirill A. Shutemov wrote:
memblock_add(entry->addr, entry->size);
if (entry->addr >= MAXMEM || end >= MAXMEM)pr_err_once("Some physical memory is not addressable in the paging mode.\n");Hi Kirill,
Thanks for fixing this!
Could we make the pr_err() a bit more informative, though? It would be nice to print out how much memory (or which addresses at least) are being thrown away.
I was also thinking that it would be handy to tell folks how to rectify the situation. Should we perhaps dump out the runtime status of X86_FEATURE_LA57?
Something like this (incremental patch)?
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index 022fe1de8940..172b4244069f 100644 --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -1280,8 +1280,8 @@ void __init e820__memory_setup(void)
void __init e820__memblock_setup(void) { + u64 size, end, not_addressable = 0; int i; - u64 end;
/* * The bootstrap memblock region count maximum is 128 entries @@ -1307,16 +1307,24 @@ void __init e820__memblock_setup(void) if (entry->type != E820_TYPE_RAM && entry->type != E820_TYPE_RESERVED_KERN) continue;
- if (entry->addr >= MAXMEM || end >= MAXMEM) - pr_err_once("Some physical memory is not addressable in the paging mode.\n"); - - if (entry->addr >= MAXMEM) + if (entry->addr >= MAXMEM) { + not_addressable += entry->size; continue; + }
end = min_t(u64, end, MAXMEM - 1); + size = end - entry->addr; + not_addressable += entry->size - size; memblock_add(entry->addr, end - entry->addr); }
+ if (not_addressable) { + pr_err("%lldMB of physical memory is not addressable in the paging mode\n", + not_addressable >> 20); + if (!pgtable_l5_enabled()) + pr_err("Consider enabling 5-level paging\n"); + } + /* Throw away partial pages: */ memblock_trim_memory(PAGE_SIZE);