diff options
| author | Kohei Enju <kohei@enjuk.jp> | 2026-04-22 02:30:24 +0000 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-04-23 11:53:31 -0700 |
| commit | e08a9fac5cf8c3fecf4755e7e3ac059f78b8f83d (patch) | |
| tree | 6f039c3f326b0858fbd7e1495ad513e5e83f5f3c | |
| parent | 076b8cad77aa96557719fb5effe8703bfb64df00 (diff) | |
vhost_net: fix sleeping with preempt-disabled in vhost_net_busy_poll()
syzbot reported "sleeping function called from invalid context" in
vhost_net_busy_poll().
Commit 030881372460 ("vhost_net: basic polling support") introduced a
busy-poll loop and preempt_{disable,enable}() around it, where each
iteration calls a sleepable function inside the loop.
The purpose of disabling preemption was to keep local_clock()-based
timeout accounting on a single CPU, rather than as a requirement of
busy-poll itself:
https://lore.kernel.org/1448435489-5949-4-git-send-email-jasowang@redhat.com
From this perspective, migrate_disable() is sufficient here, so replace
preempt_disable() with migrate_disable(), avoiding sleepable accesses
from a preempt-disabled context.
Fixes: 030881372460 ("vhost_net: basic polling support")
Tested-by: syzbot+6985cb8e543ea90ba8ee@syzkaller.appspotmail.com
Reported-by: syzbot+6985cb8e543ea90ba8ee@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/69e6a414.050a0220.24bfd3.002d.GAE@google.com/T/
Signed-off-by: Kohei Enju <kohei@enjuk.jp>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | drivers/vhost/net.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 80965181920c..c6536cad9c4f 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -560,7 +560,7 @@ static void vhost_net_busy_poll(struct vhost_net *net, busyloop_timeout = poll_rx ? rvq->busyloop_timeout: tvq->busyloop_timeout; - preempt_disable(); + migrate_disable(); endtime = busy_clock() + busyloop_timeout; while (vhost_can_busy_poll(endtime)) { @@ -577,7 +577,7 @@ static void vhost_net_busy_poll(struct vhost_net *net, cpu_relax(); } - preempt_enable(); + migrate_enable(); if (poll_rx || sock_has_rx_data(sock)) vhost_net_busy_poll_try_queue(net, vq); |