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    dm: allocate struct mapped_device with kvzalloc · 856eb091
    Mikulas Patocka 提交于
    The structure srcu_struct can be very big, its size is proportional to the
    value CONFIG_NR_CPUS. The Fedora kernel has CONFIG_NR_CPUS 8192, the field
    io_barrier in the struct mapped_device has 84kB in the debugging kernel
    and 50kB in the non-debugging kernel. The large size may result in failure
    of the function kzalloc_node.
    
    In order to avoid the allocation failure, we use the function
    kvzalloc_node, this function falls back to vmalloc if a large contiguous
    chunk of memory is not available. This patch also moves the field
    io_barrier to the last position of struct mapped_device - the reason is
    that on many processor architectures, short memory offsets result in
    smaller code than long memory offsets - on x86-64 it reduces code size by
    320 bytes.
    
    Note to stable kernel maintainers - the kernels 4.11 and older don't have
    the function kvzalloc_node, you can use the function vzalloc_node instead.
    Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
    Cc: stable@vger.kernel.org
    Signed-off-by: NMike Snitzer <snitzer@redhat.com>
    856eb091
dm.c 68.2 KB