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  • Vladimir Davydov's avatar
    memcg: unify slab and other kmem pages charging · f3ccb2c4
    Vladimir Davydov authored
    We have memcg_kmem_charge and memcg_kmem_uncharge methods for charging and
    uncharging kmem pages to memcg, but currently they are not used for
    charging slab pages (i.e.  they are only used for charging pages allocated
    with alloc_kmem_pages).  The only reason why the slab subsystem uses
    special helpers, memcg_charge_slab and memcg_uncharge_slab, is that it
    needs to charge to the memcg of kmem cache while memcg_charge_kmem charges
    to the memcg that the current task belongs to.
    To remove this diversity, this patch adds an extra argument to
    __memcg_kmem_charge that can be a pointer to a memcg or NULL.  If it is
    not NULL, the function tries to charge to the memcg it points to,
    otherwise it charge to the current context.  Next, it makes the slab
    subsystem use this function to charge slab pages.
    Since memcg_charge_kmem and memcg_uncharge_kmem helpers are now used only
    in __memcg_kmem_charge and __memcg_kmem_uncharge, they are inlined.  Since
    __memcg_kmem_charge stores a pointer to the memcg in the page struct, we
    don't need memcg_uncharge_slab anymore and can use free_kmem_pages.
    Besides, one can now detect which memcg a slab page belongs to by reading
    Note, this patch switches slab to charge-after-alloc design.  Since this
    design is already used for all other memcg charges, it should not make any
    [ better to have an outer function than a magic parameter for the memcg lookup]
    Signed-off-by: default avatarVladimir Davydov <>
    Acked-by: default avatarMichal Hocko <>
    Signed-off-by: default avatarJohannes Weiner <>
    Cc: Christoph Lameter <>
    Cc: Pekka Enberg <>
    Cc: David Rientjes <>
    Cc: Joonsoo Kim <>
    Signed-off-by: default avatarAndrew Morton <>
    Signed-off-by: default avatarLinus Torvalds <>