https://github.com/torvalds/linux
Revision 3770a42bb8ceb856877699257a43c0585a5d2996 authored by Sagi Grimberg on 05 September 2022, 15:07:06 UTC, committed by Christoph Hellwig on 06 September 2022, 04:40:44 UTC
When we queue requests, we strive to batch as much as possible and also signal the network stack that more data is about to be sent over a socket with MSG_SENDPAGE_NOTLAST. This flag looks at the pending requests queued as well as queue->more_requests that is derived from the block layer last-in-batch indication. We set more_request=true when we flush the request directly from .queue_rq submission context (in nvme_tcp_send_all), however this is wrongly assuming that no other requests may be queued during the execution of nvme_tcp_send_all. Due to this, a race condition may happen where: 1. request X is queued as !last-in-batch 2. request X submission context calls nvme_tcp_send_all directly 3. nvme_tcp_send_all is preempted and schedules to a different cpu 4. request Y is queued as last-in-batch 5. nvme_tcp_send_all context sends request X+Y, however signals for both MSG_SENDPAGE_NOTLAST because queue->more_requests=true. ==> none of the requests is pushed down to the wire as the network stack is waiting for more data, both requests timeout. To fix this, we eliminate queue->more_requests and only rely on the queue req_list and send_list to be not-empty. Fixes: 122e5b9f3d37 ("nvme-tcp: optimize network stack with setting msg flags according to batch size") Reported-by: Jonathan Nicklin <jnicklin@blockbridge.com> Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Tested-by: Jonathan Nicklin <jnicklin@blockbridge.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
1 parent 160f354
Tip revision: 3770a42bb8ceb856877699257a43c0585a5d2996 authored by Sagi Grimberg on 05 September 2022, 15:07:06 UTC
nvme-tcp: fix regression that causes sporadic requests to time out
nvme-tcp: fix regression that causes sporadic requests to time out
Tip revision: 3770a42
File | Mode | Size |
---|---|---|
Documentation | ||
LICENSES | ||
arch | ||
block | ||
certs | ||
crypto | ||
drivers | ||
fs | ||
include | ||
init | ||
io_uring | ||
ipc | ||
kernel | ||
lib | ||
mm | ||
net | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
virt | ||
.clang-format | -rw-r--r-- | 19.8 KB |
.cocciconfig | -rw-r--r-- | 59 bytes |
.get_maintainer.ignore | -rw-r--r-- | 71 bytes |
.gitattributes | -rw-r--r-- | 62 bytes |
.gitignore | -rw-r--r-- | 1.9 KB |
.mailmap | -rw-r--r-- | 23.5 KB |
COPYING | -rw-r--r-- | 496 bytes |
CREDITS | -rw-r--r-- | 99.1 KB |
Kbuild | -rw-r--r-- | 1.3 KB |
Kconfig | -rw-r--r-- | 555 bytes |
MAINTAINERS | -rw-r--r-- | 662.0 KB |
Makefile | -rw-r--r-- | 64.1 KB |
README | -rw-r--r-- | 727 bytes |
Computing file changes ...