Hi all, I've been debugging weird failures in multipathing, where 'multipath -r' would occasionally incide libdevmapper to create device nodes under /dev/mapper on it's own, instead of relying on udev for doing so. Looking in the logs, I've found: Jun 29 15:15:05 | libdevmapper: ioctl/libdm-iface.c(1725): dm reload 3600508b4000cf1c300008000002b0000 NF [16384] (*1) Jun 29 15:15:05 | libdevmapper: ioctl/libdm-iface.c(1689): Cookie value is not set while trying to call DM_DEVICE_RESUME ioctl. Please, consider using libdevmapper's udev synchronisation interface or disable it explicitly by calling dm_udev_set_sync_support(0). Jun 29 15:15:05 | libdevmapper: ioctl/libdm-iface.c(1691): Switching off device-mapper and all subsystem related udev rules. Falling back to libdevmapper node creation. Okay, that'll explain it. Then I've added a cookie to the call of DM_DEVICE_RELOAD, and encountered a hang: Jun 29 15:41:55 | 3600508b1001047395656543131580001: addmap [0 143305920 multipath 1 queue_if_no_path 0 1 1 service-time 0 1 1 104:0 1] Jun 29 15:41:55 | libdevmapper: libdm-common.c(2105): Udev cookie 0xd4d7246 (semid 6062098) created Jun 29 15:41:55 | libdevmapper: libdm-common.c(2125): Udev cookie 0xd4d7246 (semid 6062098) incremented to 1 Jun 29 15:41:55 | libdevmapper: libdm-common.c(1997): Udev cookie 0xd4d7246 (semid 6062098) incremented to 2 Jun 29 15:41:55 | libdevmapper: libdm-common.c(2238): Udev cookie 0xd4d7246 (semid 6062098) assigned to RELOAD task(1) with flags DISABLE_LIBRARY_FALLBACK (0x20) Jun 29 15:41:55 | libdevmapper: ioctl/libdm-iface.c(1725): dm reload 3600508b1001047395656543131580001 NNS [16384] (*1) Jun 29 15:41:55 | libdevmapper: libdm-common.c(2032): Udev cookie 0xd4d7246 (semid 6062098) decremented to 1 Jun 29 15:41:55 | libdevmapper: libdm-common.c(2288): Udev cookie 0xd4d7246 (semid 6062098) waiting for zero (hangs) So apparently you can only set the cookie for DM_DEVICE_RESUME, _not_ DM_DEVICE_RELOAD. Which is odd, as DM_DEVICE_RELOAD is the only call I'll ever do; apparently it's being translated internally into a suspend/reload/resume cycle. Shouldn't device-mapper take care of setting the cookie correctly? Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@xxxxxxx +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg) -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
