SCSI: mpt2sas : Fix for memory allocation error for large host credits
authornagalakshmi.nandigama@lsi.com <nagalakshmi.nandigama@lsi.com>
Thu, 1 Dec 2011 02:23:08 +0000 (07:23 +0530)
committerGreg Kroah-Hartman <gregkh@suse.de>
Wed, 18 Jan 2012 15:31:57 +0000 (07:31 -0800)
commita1f73f501a775496d33b4da523b09f64b6962251
tree107ec6dcf3b2d10470747a1bbeef32bdd849f32e
parent3e70c2626382037b67c97a706cb00788fad93527
SCSI: mpt2sas : Fix for memory allocation error for large host credits

commit aff132d95ffe14eca96cab90597cdd010b457af7 upstream.

The amount of memory required for tracking chain buffers is rather
large, and when the host credit count is big, memory allocation
failure occurs inside __get_free_pages.

The fix is to limit the number of chains to 100,000.  In addition,
the number of host credits is limited to 30,000 IOs. However this
limitation can be overridden this using the command line option
max_queue_depth.  The algorithm for calculating the
reply_post_queue_depth is changed so that it is equal to
(reply_free_queue_depth + 16), previously it was (reply_free_queue_depth * 2).

Signed-off-by: Nagalakshmi Nandigama <nagalakshmi.nandigama@lsi.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
drivers/scsi/mpt2sas/mpt2sas_base.c
drivers/scsi/mpt2sas/mpt2sas_scsih.c