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    SubjectRe: BUG at net/sunrpc/svc_xprt.c:921
    18.01.2013 03:41, Mark Lord пишет:
    > On 13-01-17 08:24 AM, Stanislav Kinsbursky wrote:
    > ..
    >> This looks like the old issue I was trying to fix with "SUNRPC: protect service sockets lists during
    >> per-net shutdown".
    >> So, here is the problem as I see it: there is a transport, which is processed by service thread and
    >> it's processing is racing with per-net service shutdown:
    >>
    >> CPU#0: CPU#1:
    >>
    >> svc_recv svc_close_net
    >> svc_get_next_xprt (list_del_init(xpt_ready))
    >> svc_close_list (set XPT_BUSY and XPT_CLOSE)
    >> svc_clear_pools(xprt was gained on CPU#0 already)
    >> svc_delete_xprt (set XPT_DEAD)
    >> svc_handle_xprt (is XPT_CLOSE => svc_delete_xprt()
    >> BUG()
    >>
    >> So, from my POW, we need some way to:
    >> 1) Skip such in-progress transports on svc_close_net() call (there is not way to detect them, or at
    >> least I don't see one)
    >> 2) Delete the transport after somewhere after svc_xprt_received()
    >>
    >> But there is a problem with svc_xprt_received(): there is a call for svc_xprt_put() in it
    >> (svc_recv->svc_handle_xprt->svc_xprt_received->svc_xprt_put) . And if we are the only user - then
    >> the transport will be destroyed. But transport is dereferenced later in svc_recv() after the
    >> svc_handle_xprt call.
    >
    > Sounds like a reference count type of problem/solution (kref) (?)
    >

    No, it would be very simple.
    Unluckily, the problem is more complex. In few words, the problem is in dynamic resources (transports) creation/attaching
    and destruction/detaching for running (!) SUNRPC service.
    You have more than one NFS mount in different network namespaces, haven't you?

    --
    Best regards,
    Stanislav Kinsbursky
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