4.19-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 2f1ee0913ce58efe7f18fbd518bd54c598559b89 ]
This reverts commit fe53ca54270a ("mm: use early_pfn_to_nid in page_ext_init").
When booting a system with "page_owner=on",
start_kernel page_ext_init invoke_init_callbacks init_section_page_ext init_page_owner init_early_allocated_pages init_zones_in_node init_pages_in_zone lookup_page_ext page_to_nid
The issue here is that page_to_nid() will not work since some page flags have no node information until later in page_alloc_init_late() due to DEFERRED_STRUCT_PAGE_INIT. Hence, it could trigger an out-of-bounds access with an invalid nid.
UBSAN: Undefined behaviour in ./include/linux/mm.h:1104:50 index 7 is out of range for type 'zone [5]'
Also, kernel will panic since flags were poisoned earlier with,
CONFIG_DEBUG_VM_PGFLAGS=y CONFIG_NODE_NOT_IN_PAGE_FLAGS=n
start_kernel setup_arch pagetable_init paging_init sparse_init sparse_init_nid memblock_alloc_try_nid_raw
It did not handle it well in init_pages_in_zone() which ends up calling page_to_nid().
page:ffffea0004200000 is uninitialized and poisoned raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) page_owner info is not active (free page?) kernel BUG at include/linux/mm.h:990! RIP: 0010:init_page_owner+0x486/0x520
This means that assumptions behind commit fe53ca54270a ("mm: use early_pfn_to_nid in page_ext_init") are incomplete. Therefore, revert the commit for now. A proper way to move the page_owner initialization to sooner is to hook into memmap initialization.
Link: http://lkml.kernel.org/r/20190115202812.75820-1-cai@lca.pw Signed-off-by: Qian Cai cai@lca.pw Acked-by: Michal Hocko mhocko@kernel.org Cc: Pasha Tatashin Pavel.Tatashin@microsoft.com Cc: Mel Gorman mgorman@techsingularity.net Cc: Yang Shi yang.shi@linaro.org Cc: Joonsoo Kim iamjoonsoo.kim@lge.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- init/main.c | 3 ++- mm/page_ext.c | 4 +--- 2 files changed, 3 insertions(+), 4 deletions(-)
diff --git a/init/main.c b/init/main.c index 18f8f0140fa0..e083fac08aed 100644 --- a/init/main.c +++ b/init/main.c @@ -689,7 +689,6 @@ asmlinkage __visible void __init start_kernel(void) initrd_start = 0; } #endif - page_ext_init(); kmemleak_init(); debug_objects_mem_init(); setup_per_cpu_pageset(); @@ -1140,6 +1139,8 @@ static noinline void __init kernel_init_freeable(void) sched_init_smp();
page_alloc_init_late(); + /* Initialize page ext after all struct pages are initialized. */ + page_ext_init();
do_basic_setup();
diff --git a/mm/page_ext.c b/mm/page_ext.c index a9826da84ccb..4961f13b6ec1 100644 --- a/mm/page_ext.c +++ b/mm/page_ext.c @@ -398,10 +398,8 @@ void __init page_ext_init(void) * We know some arch can have a nodes layout such as * -------------pfn--------------> * N0 | N1 | N2 | N0 | N1 | N2|.... - * - * Take into account DEFERRED_STRUCT_PAGE_INIT. */ - if (early_pfn_to_nid(pfn) != nid) + if (pfn_to_nid(pfn) != nid) continue; if (init_section_page_ext(pfn, nid)) goto oom;