When switching to the new iovec accessors, a negation got subtly
dropped, leading to 9p being remarkably broken (here with kvmtool):
[ 7.430941] VFS: Mounted root (9p filesystem) on device 0:15.
[ 7.432080] devtmpfs: mounted
[ 7.432717] Freeing unused kernel memory: 1344K
[ 7.433658] Run /virt/init as init process
Warning: unable to translate guest address 0x7e00902ff000 to host
Warning: unable to translate guest address 0x7e00902fefc0 to host
Warning: unable to translate guest address 0x7e00902ff000 to host
Warning: unable to translate guest address 0x7e008febef80 to host
Warning: unable to translate guest address 0x7e008febf000 to host
Warning: unable to translate guest address 0x7e008febef00 to host
Warning: unable to translate guest address 0x7e008febf000 to host
[ 7.436376] Kernel panic - not syncing: Requested init /virt/init failed
(error -8).
[ 7.437554] CPU: 29 PID: 1 Comm: swapper/0 Not tainted
4.19.0-rc8-02267-g00e23707442a #291
[ 7.439006] Hardware name: linux,dummy-virt (DT)
[ 7.439902] Call trace:
[ 7.440387] dump_backtrace+0x0/0x148
[ 7.441104] show_stack+0x14/0x20
[ 7.441768] dump_stack+0x90/0xb4
[ 7.442425] panic+0x120/0x27c
[ 7.443036] kernel_init+0xa4/0x100
[ 7.443725] ret_from_fork+0x10/0x18
[ 7.444444] SMP: stopping secondary CPUs
[ 7.445391] Kernel Offset: disabled
[ 7.446169] CPU features: 0x0,23000438
[ 7.446974] Memory Limit: none
[ 7.447645] ---[ end Kernel panic - not syncing: Requested init /virt/init
failed (error -8). ]---
Restoring the missing "!" brings the guest back to life.
Fixes: 00e23707442a ("iov_iter: Use accessor function")
Reported-by: Will Deacon <will.dea...@arm.com>
Acked-by: Al Viro <v...@zeniv.linux.org.uk>
Signed-off-by: Marc Zyngier <marc.zyng...@arm.com>
---
Reposting with Al's ack, for Linus to pick up
as per https://lore.kernel.org/lkml/20181102190433.gz32...@zeniv.linux.org.uk/
net/9p/trans_virtio.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index 91981970f542..b1d39cabf125 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -329,7 +329,7 @@ static int p9_get_mapped_pages(struct virtio_chan *chan,
if (!iov_iter_count(data))
return 0;
- if (iov_iter_is_kvec(data)) {
+ if (!iov_iter_is_kvec(data)) {
int n;
/*
* We allow only p9_max_pages pinned. We wait for the
--
2.19.1
