• Pavel Tatashin's avatar
    sparc64/mm: set fields in deferred pages · 2a20aa17
    Pavel Tatashin authored
    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: default avatarPavel Tatashin <pasha.tatashin@oracle.com>
    Reviewed-by: default avatarSteven Sistare <steven.sistare@oracle.com>
    Reviewed-by: default avatarDaniel Jordan <daniel.m.jordan@oracle.com>
    Reviewed-by: default avatarBob Picco <bob.picco@oracle.com>
    Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
    Acked-by: default avatarMichal 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: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    2a20aa17