• Daniel Borkmann's avatar
    bpf: don't trigger OOM killer under pressure with map alloc · 251d00bf
    Daniel Borkmann authored
    
    [ Upstream commit d407bd25 ]
    
    This patch adds two helpers, bpf_map_area_alloc() and bpf_map_area_free(),
    that are to be used for map allocations. Using kmalloc() for very large
    allocations can cause excessive work within the page allocator, so i) fall
    back earlier to vmalloc() when the attempt is considered costly anyway,
    and even more importantly ii) don't trigger OOM killer with any of the
    allocators.
    
    Since this is based on a user space request, for example, when creating
    maps with element pre-allocation, we really want such requests to fail
    instead of killing other user space processes.
    
    Also, don't spam the kernel log with warnings should any of the allocations
    fail under pressure. Given that, we can make backend selection in
    bpf_map_area_alloc() generic, and convert all maps over to use this API
    for spots with potentially large allocation requests.
    
    Note, replacing the one kmalloc_array() is fine as overflow checks happen
    earlier in htab_map_alloc(), since it must also protect the multiplication
    for vmalloc() should kmalloc_array() fail.
    Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
    Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    Signed-off-by: default avatarSasha Levin <alexander.levin@verizon.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    251d00bf
hashtab.c 19.2 KB