linux/drivers/s390
Steffen Maier 9edf7d75ee [SCSI] zfcp: status read buffers on first adapter open with link down
Commit 64deb6efdc
"[SCSI] zfcp: Use status_read_buf_num provided by FCP channel"
started using a value returned by the channel but only evaluated the value
if the fabric link is up.
Commit 8d88cf3f3b
"[SCSI] zfcp: Update status read mempool"
introduced mempool resizings based on the above value.
On setting an FCP device online for the very first time since boot, a new
zeroed adapter object is allocated. If the link is down, the number of
status read requests remains zero. Since just the config data exchange is
incomplete, we proceed with adapter open recovery. However, we
unconditionally call mempool_resize with adapter->stat_read_buf_num == 0 in
this case.

This causes a kernel message "kernel BUG at mm/mempool.c:131!" in process
"zfcperp<FCP-device-bus-ID>" with last function mempool_resize in Krnl PSW
and zfcp_erp_thread in the Call Trace.

Don't evaluate channel values which are invalid on link down. The number of
status read requests is always valid, evaluated, and set to a positive
minimum greater than zero. The adapter open recovery can proceed and the
channel has status read buffers to inform us on a future link up event.
While we are not aware of any other code path that could result in mempool
resize attempts of size zero, we still also initialize the number of status
read buffers to be posted to a static minimum number on adapter object
allocation.

Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org> #2.6.35+
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
2013-05-31 16:32:38 -07:00
..
block Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2013-05-21 09:36:46 -07:00
char s390/memory hotplug,sclp: get rid of per memory increment usecount 2013-05-02 15:50:28 +02:00
cio s390/cio: add channel ID sysfs attribute 2013-05-15 16:47:39 +02:00
crypto s390/zcrypt: ap bus rescan problem when toggle crypto adapters on/off 2013-05-02 17:10:20 +02:00
kvm Merge tag 'kvm-3.10-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm 2013-05-05 14:47:31 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2013-04-22 20:32:51 -04:00
scsi [SCSI] zfcp: status read buffers on first adapter open with link down 2013-05-31 16:32:38 -07:00
Makefile [S390] split/move machine check handler code 2009-03-26 15:24:10 +01:00