• Linus Torvalds's avatar
    mm: split 'tlb_flush_mmu()' into tlb flushing and memory freeing parts · 1cf35d47
    Linus Torvalds authored
    The mmu-gather operation 'tlb_flush_mmu()' has done two things: the
    actual tlb flush operation, and the batched freeing of the pages that
    the TLB entries pointed at.
    
    This splits the operation into separate phases, so that the forced
    batched flushing done by zap_pte_range() can now do the actual TLB flush
    while still holding the page table lock, but delay the batched freeing
    of all the pages to after the lock has been dropped.
    
    This in turn allows us to avoid a race condition between
    set_page_dirty() (as called by zap_pte_range() when it finds a dirty
    shared memory pte) and page_mkclean(): because we now flush all the
    dirty page data from the TLB's while holding the pte lock,
    page_mkclean() will be held up walking the (recently cleaned) page
    tables until after the TLB entries have been flushed from all CPU's.
    Reported-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
    Tested-by: default avatarDave Hansen <dave.hansen@intel.com>
    Acked-by: default avatarHugh Dickins <hughd@google.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>
    Cc: Tony Luck <tony.luck@intel.com>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    1cf35d47
memory.c 120 KB