Description of Problem: I have a system configured with a LSI MegaRAID Elite 1600 and two Intel Dual EtherExpress Pro 100 PCI NICs. The PCI devices are plugged into an "active" 3 slot riser with built-in bridge chip. The MegaRAID card is configured with a RAID 5 array over four Hitachi DK32DJ-36MC disks. Each port on a NIC is configured to loopback to the corresponding port on the other NIC (i.e. port0 on card0 is loopbacked to port0 on card1, and so on.). When running a flood ping on each ethernet interface and a bonnie++ variant on the disks, the following kernel message comes up: May 28 06:33:00 eng163 kernel: ISR called reentrantly!! It usually apears a few at a time every 10-15 minutes. This seems to be generated by the megaraid driver's interrupt service routine. The megaraid and one of the ethernet interfaces share the same interrupt. I haven't seen the problem occur when the disks are idle or when the ethernet interface (which shares the same interrupt) is idle. The system has been stable and I haven't seen any filesystem problems or dropped packets. Its been running for days with no problem except for the kernel message. Version-Release number of selected component (if applicable): RedHat 7.3 errata (2.4.18-4smp, megaraid.c v.1.18a) How Reproducible: Always Steps to Reproduce: 1. induce heavy I/O load 2. 3. Actual Results: May 28 06:33:00 eng163 kernel: ISR called reentrantly!! Expected Results: No kernel message. Additional Information:
Created attachment 58789 [details] /proc/interrupts
Created attachment 58790 [details] lspci
Created attachment 58791 [details] dmesg
I've seen it too on my box, also never with hangs. (but mostly with 2.4.9 kernels) From doing some work on the driver it appears to be a race in the accounting of this and it's just a stupid printk that triggers.... but the megaraid driver isn't that great performance wise..... it needs a big cleanup/fixup