• Joonsoo Kim's avatar
    slub: fix a memory leak in get_partial_node() · 02d7633f
    Joonsoo Kim authored
    In the case which is below,
    
    1. acquire slab for cpu partial list
    2. free object to it by remote cpu
    3. page->freelist = t
    
    then memory leak is occurred.
    
    Change acquire_slab() not to zap freelist when it works for cpu partial list.
    I think it is a sufficient solution for fixing a memory leak.
    
    Below is output of 'slabinfo -r kmalloc-256'
    when './perf stat -r 30 hackbench 50 process 4000 > /dev/null' is done.
    
    ***Vanilla***
    Sizes (bytes)     Slabs              Debug                Memory
    ------------------------------------------------------------------------
    Object :     256  Total  :     468   Sanity Checks : Off  Total: 3833856
    SlabObj:     256  Full   :     111   Redzoning     : Off  Used : 2004992
    SlabSiz:    8192  Partial:     302   Poisoning     : Off  Loss : 1828864
    Loss   :       0  CpuSlab:      55   Tracking      : Off  Lalig:       0
    Align  :       8  Objects:      32   Tracing       : Off  Lpadd:       0
    
    ***Patched***
    Sizes (bytes)     Slabs              Debug                Memory
    ------------------------------------------------------------------------
    Object :     256  Total  :     300   Sanity Checks : Off  Total: 2457600
    SlabObj:     256  Full   :     204   Redzoning     : Off  Used : 2348800
    SlabSiz:    8192  Partial:      33   Poisoning     : Off  Loss :  108800
    Loss   :       0  CpuSlab:      63   Tracking      : Off  Lalig:       0
    Align  :       8  Objects:      32   Tracing       : Off  Lpadd:       0
    
    Total and loss number is the impact of this patch.
    
    Cc: <stable@vger.kernel.org>
    Acked-by: default avatarChristoph Lameter <cl@linux.com>
    Signed-off-by: default avatarJoonsoo Kim <js1304@gmail.com>
    Signed-off-by: default avatarPekka Enberg <penberg@kernel.org>
    02d7633f
slub.c 129 KB