From: Pavel Tatashin pasha.tatashin@oracle.com
[ Upstream commit 2a20aa171071a334d80c4e5d5af719d8374702fc ]
Without deferred struct page feature (CONFIG_DEFERRED_STRUCT_PAGE_INIT), flags and other fields in "struct page"es are never changed prior to first initializing struct pages by going through __init_single_page().
With deferred struct page feature enabled there is a case where we set some fields prior to initializing:
mem_init() { register_page_bootmem_info(); free_all_bootmem(); ... }
When register_page_bootmem_info() is called only non-deferred struct pages are initialized. But, this function goes through some reserved pages which might be part of the deferred, and thus are not yet initialized.
mem_init register_page_bootmem_info register_page_bootmem_info_node get_page_bootmem .. setting fields here .. such as: page->freelist = (void *)type;
free_all_bootmem() free_low_memory_core_early() for_each_reserved_mem_region() reserve_bootmem_region() init_reserved_page() <- Only if this is deferred reserved page __init_single_pfn() __init_single_page() memset(0) <-- Loose the set fields here
We end up with similar issue as in the previous patch, where currently we do not observe problem as memory is zeroed. But, if flag asserts are changed we can start hitting issues.
Also, because in this patch series we will stop zeroing struct page memory during allocation, we must make sure that struct pages are properly initialized prior to using them.
The deferred-reserved pages are initialized in free_all_bootmem(). Therefore, the fix is to switch the above calls.
Link: http://lkml.kernel.org/r/20171013173214.27300-4-pasha.tatashin@oracle.com Signed-off-by: Pavel Tatashin pasha.tatashin@oracle.com Reviewed-by: Steven Sistare steven.sistare@oracle.com Reviewed-by: Daniel Jordan daniel.m.jordan@oracle.com Reviewed-by: Bob Picco bob.picco@oracle.com Acked-by: David S. Miller davem@davemloft.net Acked-by: Michal Hocko mhocko@suse.com Cc: Alexander Potapenko glider@google.com Cc: Andrey Ryabinin aryabinin@virtuozzo.com Cc: Ard Biesheuvel ard.biesheuvel@linaro.org Cc: Catalin Marinas catalin.marinas@arm.com Cc: Christian Borntraeger borntraeger@de.ibm.com Cc: Dmitry Vyukov dvyukov@google.com Cc: Heiko Carstens heiko.carstens@de.ibm.com Cc: "H. Peter Anvin" hpa@zytor.com Cc: Ingo Molnar mingo@redhat.com Cc: Mark Rutland mark.rutland@arm.com Cc: Matthew Wilcox willy@infradead.org Cc: Mel Gorman mgorman@techsingularity.net Cc: Michal Hocko mhocko@kernel.org Cc: Sam Ravnborg sam@ravnborg.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Will Deacon will.deacon@arm.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin alexander.levin@verizon.com --- arch/sparc/mm/init_64.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c index 7ad1baa6c914..1f4492f6efb0 100644 --- a/arch/sparc/mm/init_64.c +++ b/arch/sparc/mm/init_64.c @@ -2215,10 +2215,17 @@ void __init mem_init(void) { high_memory = __va(last_valid_pfn << PAGE_SHIFT);
- register_page_bootmem_info(); free_all_bootmem();
/* + * Must be done after boot memory is put on freelist, because here we + * might set fields in deferred struct pages that have not yet been + * initialized, and free_all_bootmem() initializes all the reserved + * deferred pages for us. + */ + register_page_bootmem_info(); + + /* * Set up the zero page, mark it reserved, so that page count * is not manipulated when freeing the page from user ptes. */