| Message ID | 20181220185031.43146-1-cai@lca.pw (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] mm/page_owner: fix for deferred struct page init | expand |
On Thu 20-12-18 13:50:31, Qian Cai wrote: > 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. > > [ 8.666047] UBSAN: Undefined behaviour in ./include/linux/mm.h:1104:50 > [ 8.672603] 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 > > Although later it tries to set page flags for pages in reserved bootmem > regions, > > mm_init > mem_init > memblock_free_all > free_low_memory_core_early > reserve_bootmem_region > > there could still have some freed pages from the page allocator but yet > to be initialized due to DEFERRED_STRUCT_PAGE_INIT. It have already been > dealt with a bit in page_ext_init(). > > * Take into account DEFERRED_STRUCT_PAGE_INIT. > */ > if (early_pfn_to_nid(pfn) != nid) > continue; > > However it did not handle it well in init_pages_in_zone() which end up > calling page_to_nid(). > > [ 11.917212] page:ffffea0004200000 is uninitialized and poisoned > [ 11.917220] raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff > ffffffffffffffff > [ 11.921745] raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff > ffffffffffffffff > [ 11.924523] page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) > [ 11.926498] page_owner info is not active (free page?) > [ 12.329560] kernel BUG at include/linux/mm.h:990! > [ 12.337632] RIP: 0010:init_page_owner+0x486/0x520 > > Since there is no other routines depend on page_ext_init() in > start_kernel() and no real benefit to call it so early, just move it > after page_alloc_init_late() to ensure that there is no deferred pages > need to de dealt with. The last paragraph should be updated. I would propose something like this. " This means that assumptions behind 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. " > Fixes: fe53ca54270a ("mm: use early_pfn_to_nid in page_ext_init") > Suggested-by: Michal Hocko <mhocko@kernel.org> > Signed-off-by: Qian Cai <cai@lca.pw> Acked-by: Michal Hocko <mhocko@suse.com> > --- > > v2: postpone init_page_ext() to after page_alloc_init_late(). > > init/main.c | 2 +- > mm/page_ext.c | 3 +-- > 2 files changed, 2 insertions(+), 3 deletions(-) > > diff --git a/init/main.c b/init/main.c > index 2b7b7fe173c9..1aeb062b2cb7 100644 > --- a/init/main.c > +++ b/init/main.c > @@ -696,7 +696,6 @@ asmlinkage __visible void __init start_kernel(void) > initrd_start = 0; > } > #endif > - page_ext_init(); > kmemleak_init(); > setup_per_cpu_pageset(); > numa_policy_init(); > @@ -1147,6 +1146,7 @@ static noinline void __init kernel_init_freeable(void) > sched_init_smp(); > > page_alloc_init_late(); > + page_ext_init(); > > do_basic_setup(); > > diff --git a/mm/page_ext.c b/mm/page_ext.c > index ae44f7adbe07..d76fd51e312a 100644 > --- a/mm/page_ext.c > +++ b/mm/page_ext.c > @@ -399,9 +399,8 @@ void __init page_ext_init(void) > * -------------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; > -- > 2.17.2 (Apple Git-113)
diff --git a/init/main.c b/init/main.c index 2b7b7fe173c9..1aeb062b2cb7 100644 --- a/init/main.c +++ b/init/main.c @@ -696,7 +696,6 @@ asmlinkage __visible void __init start_kernel(void) initrd_start = 0; } #endif - page_ext_init(); kmemleak_init(); setup_per_cpu_pageset(); numa_policy_init(); @@ -1147,6 +1146,7 @@ static noinline void __init kernel_init_freeable(void) sched_init_smp(); page_alloc_init_late(); + page_ext_init(); do_basic_setup(); diff --git a/mm/page_ext.c b/mm/page_ext.c index ae44f7adbe07..d76fd51e312a 100644 --- a/mm/page_ext.c +++ b/mm/page_ext.c @@ -399,9 +399,8 @@ void __init page_ext_init(void) * -------------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;
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. [ 8.666047] UBSAN: Undefined behaviour in ./include/linux/mm.h:1104:50 [ 8.672603] 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 Although later it tries to set page flags for pages in reserved bootmem regions, mm_init mem_init memblock_free_all free_low_memory_core_early reserve_bootmem_region there could still have some freed pages from the page allocator but yet to be initialized due to DEFERRED_STRUCT_PAGE_INIT. It have already been dealt with a bit in page_ext_init(). * Take into account DEFERRED_STRUCT_PAGE_INIT. */ if (early_pfn_to_nid(pfn) != nid) continue; However it did not handle it well in init_pages_in_zone() which end up calling page_to_nid(). [ 11.917212] page:ffffea0004200000 is uninitialized and poisoned [ 11.917220] raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff [ 11.921745] raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff [ 11.924523] page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) [ 11.926498] page_owner info is not active (free page?) [ 12.329560] kernel BUG at include/linux/mm.h:990! [ 12.337632] RIP: 0010:init_page_owner+0x486/0x520 Since there is no other routines depend on page_ext_init() in start_kernel() and no real benefit to call it so early, just move it after page_alloc_init_late() to ensure that there is no deferred pages need to de dealt with. Suggested-by: Michal Hocko <mhocko@kernel.org> Signed-off-by: Qian Cai <cai@lca.pw> --- v2: postpone init_page_ext() to after page_alloc_init_late(). init/main.c | 2 +- mm/page_ext.c | 3 +-- 2 files changed, 2 insertions(+), 3 deletions(-)