• Christian Borntraeger's avatar
    [S390] pgtables: Fix race in enable_sie vs. page table ops · 250cf776
    Christian Borntraeger authored
    The current enable_sie code sets the mm->context.pgstes bit to tell
    dup_mm that the new mm should have extended page tables. This bit is also
    used by the s390 specific page table primitives to decide about the page
    table layout - which means context.pgstes has two meanings. This can cause
    any kind of bugs. For example  - e.g. shrink_zone can call
    ptep_clear_flush_young while enable_sie is running. ptep_clear_flush_young
    will test for context.pgstes. Since enable_sie changed that value of the old
    struct mm without changing the page table layout ptep_clear_flush_young will
    do the wrong thing.
    The solution is to split pgstes into two bits
    - one for the allocation
    - one for the current state
    Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
    Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
    250cf776
mmu_context.h 2.55 KB