From 1d5e4640e5df15252398c1b621f6bd432f2d7f17 Mon Sep 17 00:00:00 2001 From: Vladimir Isaev Date: Tue, 27 Apr 2021 15:13:54 +0300 Subject: [PATCH] ARC: mm: Use max_high_pfn as a HIGHMEM zone border Commit 4af22ded0ecf ("arc: fix memory initialization for systems with two memory banks") fixed highmem, but for the PAE case it causes bug messages: | BUG: Bad page state in process swapper pfn:80000 | page:(ptrval) refcount:0 mapcount:1 mapping:00000000 index:0x0 pfn:0x80000 flags: 0x0() | raw: 00000000 00000100 00000122 00000000 00000000 00000000 00000000 00000000 | raw: 00000000 | page dumped because: nonzero mapcount | Modules linked in: | CPU: 0 PID: 0 Comm: swapper Not tainted 5.12.0-rc5-00003-g1e43c377a79f #1 This is because the fix expects highmem to be always less than lowmem and uses min_low_pfn as an upper zone border for highmem. max_high_pfn should be ok for both highmem and highmem+PAE cases. Fixes: 4af22ded0ecf ("arc: fix memory initialization for systems with two memory banks") Signed-off-by: Vladimir Isaev Cc: Mike Rapoport Cc: stable@vger.kernel.org #5.8 onwards Signed-off-by: Vineet Gupta --- arch/arc/mm/init.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c index 33832e3..e2ed355 100644 --- a/arch/arc/mm/init.c +++ b/arch/arc/mm/init.c @@ -157,7 +157,16 @@ void __init setup_arch_memory(void) min_high_pfn = PFN_DOWN(high_mem_start); max_high_pfn = PFN_DOWN(high_mem_start + high_mem_sz); - max_zone_pfn[ZONE_HIGHMEM] = min_low_pfn; + /* + * max_high_pfn should be ok here for both HIGHMEM and HIGHMEM+PAE. + * For HIGHMEM without PAE max_high_pfn should be less than + * min_low_pfn to guarantee that these two regions don't overlap. + * For PAE case highmem is greater than lowmem, so it is natural + * to use max_high_pfn. + * + * In both cases, holes should be handled by pfn_valid(). + */ + max_zone_pfn[ZONE_HIGHMEM] = max_high_pfn; high_memory = (void *)(min_high_pfn << PAGE_SHIFT); -- 2.7.4