Description of problem: While Running I/O to tape devices, kernel reports "Kernel BUG at pci_dma" when the qla2300 FC HBA calls the pci_map_sg(). Looking at the dump it turns out that the offset being passed down in non zero, but the page address was NULL. Tracing back to the tape driver, one of the issue we found was that the scatter gather memory being allocated was not being initialized to zero. The following patch address this issue. --- st.c.orig 2006-02-08 12:35:52.000000000 -0800 +++ st.c 2006-02-08 12:36:11.000000000 -0800 @@ -3434,6 +3434,7 @@ st_max_sg_segs * sizeof(unsigned int); tb = kmalloc(i, priority); if (tb) { + memset(tb, 0, i); tb->sg_lengths = (unsigned int *)(&tb->sg[0] + st_max_sg_segs); if (need_dma) Let us know if there is any issue or concern. We would like this patch to be rolled into the next RHEL 3.0 update, hopefully U8. Ravi Anand QLogic Corporation. Version-Release number of selected component (if applicable): RHEL 3.0 U6 on x86_64 bit system using Tape driver. How reproducible: Within an hour or so it happens while running I/O to tape devices. It was seen on couple of x86_64 system. Steps to Reproduce: 1. Load qla2300.o driver. Driver version used was 7.07.01 with tape devices attached on RH EL 3.0 U6 64bit system (opteron) and start running I/O to the tape device Actual results: System halts with "Kernel BUG at pci_dma" Expected results: Additional info:
Any update on this issue ? Ravi
(In reply to comment #3) > Any update on this issue ? I've tested it on my lab system, and although I haven't reproduced the bug I can confirm that the patch (as expected) does no harm. I'll submit it to our internal kernel list for review. Chip
(In reply to comment #3) > Any update on this issue ? > > Ravi This patch will go in to RHEL3 U8. Thanks for finding/fixing this bug. Chip
A fix for this problem has just been committed to the RHEL3 U8 patch pool this evening (in kernel version 2.4.21-40.5.EL).
This issue is on Red Hat Engineering's list of planned work items for the upcoming Red Hat Enterprise Linux 3.8 release. Engineering resources have been assigned and barring unforeseen circumstances, Red Hat intends to include this item in the 3.8 release.
*** Bug 185183 has been marked as a duplicate of this bug. ***
An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on the solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHSA-2006-0437.html