[Scst-devel] filp_open returns ENOMEM - help to debug

[Adrian S. <Adr...@tp...>]

I occasionally have some host groups on my SCST/pacemaker/ceph system fall into an error state, usually triggered by some sort of system pause that causes pacemaker to start bouncing things.   Even though I can clean up most of it, sometimes I end up with errors like this repeating every time particular iSCSI clients try to reconnect:

Jan 10 11:05:36 ceph-glb-fec-02 iscsi-scstd: Connect from 10.132.197.70:54669 to 10.132.197.67:3260
Jan 10 11:05:36 ceph-glb-fec-02 kernel: [2767]: scst: Using security group "hyperv-glebe" for initiator "iqn.1991-05.com.microsoft:hv-glb-wst-1" (target iqn.2016-09.tpg.ceph.glebe:ceph-glb-fec-02)
Jan 10 11:05:36 ceph-glb-fec-02 kernel: [2767]: dev_vdisk: ***ERROR***: filp_open(/dev/rbd/glebe-sata/hypervtst-lun00) failed: -30
Jan 10 11:05:36 ceph-glb-fec-02 kernel: [2767]: scst: ***ERROR***: Device handler's vdisk_blockio attach_tgt() failed: -30
Jan 10 11:05:36 ceph-glb-fec-02 kernel: [2767]: iscsi-scst: ***ERROR***: scst_register_session() failed
Jan 10 11:05:36 ceph-glb-fec-02 iscsi-scstd: Can't create sess 0xfaba010037010040 (tid 2, initiator iqn.1991-05.com.microsoft:hv-glb-wst-1): Cannot allocate memory

Clearly the problem is that filp_open is returning ENOMEM, but as best I can tell there is no memory pressure on the system and the RBD device is mapped, the device is configured in SCST as normal and all appears well, except that this session failures continually occur.

Any suggestions on how I can debug where the ENOMEM is coming from for filp_open.  I have done some reading of the source code but there isn't anything obvious I can find from that on where to start tracking this down.  I would like to figure it out rather than just rebooting and clearing it.

Thanks,
Adrian

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