• David Miller's avatar
    mm: thp: Use more portable PMD clearing sequenece in zap_huge_pmd(). · f5c8ad47
    David Miller authored
    Invalidation sequences are handled in various ways on various
    architectures.
    
    One way, which sparc64 uses, is to let the set_*_at() functions accumulate
    pending flushes into a per-cpu array.  Then the flush_tlb_range() et al.
    calls process the pending TLB flushes.
    
    In this regime, the __tlb_remove_*tlb_entry() implementations are
    essentially NOPs.
    
    The canonical PTE zap in mm/memory.c is:
    
    			ptent = ptep_get_and_clear_full(mm, addr, pte,
    							tlb->fullmm);
    			tlb_remove_tlb_entry(tlb, pte, addr);
    
    With a subsequent tlb_flush_mmu() if needed.
    
    Mirror this in the THP PMD zapping using:
    
    		orig_pmd = pmdp_get_and_clear(tlb->mm, addr, pmd);
    		page = pmd_page(orig_pmd);
    		tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
    
    And we properly accomodate TLB flush mechanims like the one described
    above.
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    Cc: Andrea Arcangeli <aarcange@redhat.com>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    f5c8ad47
huge_memory.c 63.5 KB