4.17-stable review patch. If anyone has any objections, please let me know.
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From: Pavel Tatashin pasha.tatashin@oracle.com
commit e181ae0c5db9544de9c53239eb22bc012ce75033 upstream.
We must zero struct pages for memory that is not backed by physical memory, or kernel does not have access to.
Recently, there was a change which zeroed all memmap for all holes in e820. Unfortunately, it introduced a bug that is discussed here:
https://www.spinics.net/lists/linux-mm/msg156764.html
Linus, also saw this bug on his machine, and confirmed that reverting commit 124049decbb1 ("x86/e820: put !E820_TYPE_RAM regions into memblock.reserved") fixes the issue.
The problem is that we incorrectly zero some struct pages after they were setup.
The fix is to zero unavailable struct pages prior to initializing of struct pages.
A more detailed fix should come later that would avoid double zeroing cases: one in __init_single_page(), the other one in zero_resv_unavail().
Fixes: 124049decbb1 ("x86/e820: put !E820_TYPE_RAM regions into memblock.reserved") Signed-off-by: Pavel Tatashin pasha.tatashin@oracle.com Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- mm/page_alloc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6841,6 +6841,7 @@ void __init free_area_init_nodes(unsigne /* Initialise every node */ mminit_verify_pageflags_layout(); setup_nr_node_ids(); + zero_resv_unavail(); for_each_online_node(nid) { pg_data_t *pgdat = NODE_DATA(nid); free_area_init_node(nid, NULL, @@ -6851,7 +6852,6 @@ void __init free_area_init_nodes(unsigne node_set_state(nid, N_MEMORY); check_for_memory(pgdat, nid); } - zero_resv_unavail(); }
static int __init cmdline_parse_core(char *p, unsigned long *core, @@ -7027,9 +7027,9 @@ void __init set_dma_reserve(unsigned lon
void __init free_area_init(unsigned long *zones_size) { + zero_resv_unavail(); free_area_init_node(0, zones_size, __pa(PAGE_OFFSET) >> PAGE_SHIFT, NULL); - zero_resv_unavail(); }
static int page_alloc_cpu_dead(unsigned int cpu)