• NeilBrown's avatar
    SUNRPC/call_alloc: async tasks mustn't block waiting for memory · c487216b
    NeilBrown authored
    When memory is short, new worker threads cannot be created and we depend
    on the minimum one rpciod thread to be able to handle everything.
    So it must not block waiting for memory.
    
    mempools are particularly a problem as memory can only be released back
    to the mempool by an async rpc task running.  If all available
    workqueue threads are waiting on the mempool, no thread is available to
    return anything.
    
    rpc_malloc() can block, and this might cause deadlocks.
    So check RPC_IS_ASYNC(), rather than RPC_IS_SWAPPER() to determine if
    blocking is acceptable.
    Signed-off-by: default avatarNeilBrown <neilb@suse.de>
    Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
    c487216b
sched.c 33.1 KB