Bug 33972
| Summary: | Bogus UDP Fragmentation Offload packet generation | ||
|---|---|---|---|
| Product: | Networking | Reporter: | Leszek Urbanski (tgr.kb) |
| Component: | IPV4 | Assignee: | Stephen Hemminger (stephen) |
| Status: | CLOSED DOCUMENTED | ||
| Severity: | high | CC: | alan, paul.gortmaker |
| Priority: | P1 | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Kernel Version: | 2.6.32.x | Subsystem: | |
| Regression: | Yes | Bisected commit-id: | |
| Attachments: | udp: Fix bogus UFO packet generation | ||
Upstream commit ID is 26cde9f7e2747b6d254b704594eed87ab959afa5 If it needs pushing to stable trees still please email Herbert and ask him to push it on commit 26cde9f7e2747b6d254b704594eed87ab959afa5 Author: Herbert Xu <herbert@gondor.apana.org.au> Date: Tue Jun 15 01:52:25 2010 +0000 |
Created attachment 55552 [details] udp: Fix bogus UFO packet generation The new UFO software fallback path fails under certain conditions with NFS and causes partial connectivity loss due to generation of UFO packets smaller than the MTU, which are then discarded by the software fallback path. How to reproduce: copy a large file to an NFS mount with UFO enabled and going through the software fallback path, e.g. on a KVM guest with virtio-net and qdev device syntax: -device virtio-net-pci,netdev=tap1,mac=ab:cd:ef:01:23:45 \ -netdev type=tap,id=tap1,ifname=tap1 All NFS mounts immediately stall and processes go into D state, stuck on nfs_wait_bit_uninterruptible. There is no further communication between the client and the server. It has been fixed in 2.6.35-rc4 by Herbert Xu (patch for net/ipv4/ip_output.c attached). However, it's still not in 2.6.32.x longterm (as of 2.6.32.39).