On Fri, May 30, 2014 at 4:26 PM, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > Il 30/05/2014 10:15, Liu Ping Fan ha scritto: > >> When running io stress test on large latency scsi-disk, e.g guest with >> virtscsi >> on a nfs image. It can trigger the BUG_ON(test_bit(REQ_ATOM_COMPLETE, >> &req->atomic_flags)); >> in blk_start_request(). >> Since there is a race between latency "finishing" scmd and the >> re-allocated scmd. >> I.e a request is still referred by a scmd, but we had turn it back to >> slab. >> >> This series introduces the ref on scmd to exclude this issue, and the >> following is ref rules. >> >> inc ref rules is like the following: >> When setup a scmd, inited as 1. When add a timer inc 1. >> >> dec ref rules is like the following: >> -for the normal ref >> scsi_done() will drop the ref when fail to acquire >> REQ_ATOM_COMPLETE immediately >> or drop the ref by scsi_end_request() >> or drop by return SUCCESS_REMOVE >> -for a timer ref >> when deleting timer, if !list_empty(timeout_list), then there is a >> timer ref, and >> drop it. >> >> >> patch1-2: fix the current potential bug >> patch3~6: prepare for the mechanism for the ref >> patch7: the ref rules core >> patch8-9: e.g and test-issue for the new mechanism. Since lack of many >> virtscsi background, >> patch8 may be poor and need to be improved :) >> >> >> Note: all the patches are based on rhel7, whose kernel version is >> linux-3.10. >> I will rebase them onto the latest commit if my method is practical. > > > This series is not necessary, this is a bug in the virtscsi driver. I have > a ten line patch to fix it, but I haven't yet tested it properly. > Could I pick up your patch, and test it? Thx, Fan > Paolo > > -- > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
