• Tejun Heo's avatar
    workqueue: fix ordered workqueues in NUMA setups · 8a2b7538
    Tejun Heo authored
    An ordered workqueue implements execution ordering by using single
    pool_workqueue with max_active == 1.  On a given pool_workqueue, work
    items are processed in FIFO order and limiting max_active to 1
    enforces the queued work items to be processed one by one.
    
    Unfortunately, 4c16bd32 ("workqueue: implement NUMA affinity for
    unbound workqueues") accidentally broke this guarantee by applying
    NUMA affinity to ordered workqueues too.  On NUMA setups, an ordered
    workqueue would end up with separate pool_workqueues for different
    nodes.  Each pool_workqueue still limits max_active to 1 but multiple
    work items may be executed concurrently and out of order depending on
    which node they are queued to.
    
    Fix it by using dedicated ordered_wq_attrs[] when creating ordered
    workqueues.  The new attrs match the unbound ones except that no_numa
    is always set thus forcing all NUMA nodes to share the default
    pool_workqueue.
    
    While at it, add sanity check in workqueue creation path which
    verifies that an ordered workqueues has only the default
    pool_workqueue.
    Signed-off-by: default avatarTejun Heo <tj@kernel.org>
    Reported-by: default avatarLibin <huawei.libin@huawei.com>
    Cc: stable@vger.kernel.org
    Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
    8a2b7538
workqueue.c 141 KB