Re: [syzbot] [kvm?] [net?] [virt?] BUG: sleeping function called from invalid context in vhost_get_avail_idx

[Kohei Enju]

-netdev, Jason, Michael, not to spam them

On 04/21 12:03, syzbot wrote:
> Hello,
> 
> syzbot tried to test the proposed patch but the build/boot failed:

I don't this this failure is caused by the patch, so retrying...

#syz test

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);


> 
> failed to copy syz-execprog to VM: scp failed: failed to run ["scp" "-P" "36338" "-F" "/dev/null" "-o" "UserKnownHostsFile=/dev/null" "-o" "IdentitiesOnly=yes" "-o" "BatchMode=yes" "-o" "StrictHostKeyChecking=no" "-o" "ConnectTimeout=10" "-v" "/syzkaller/jobs/linux/gopath/src/github.com/google/syzkaller/bin/linux_amd64/syz-execprog" "root@localhost:/syz-execprog"]: exit status 1
> 
> 
> 
> syzkaller build log:
> go env (err=<nil>)
> AR='ar'
> CC='gcc'
> CGO_CFLAGS='-O2 -g'
> CGO_CPPFLAGS=''
> CGO_CXXFLAGS='-O2 -g'
> CGO_ENABLED='1'
> CGO_FFLAGS='-O2 -g'
> CGO_LDFLAGS='-O2 -g'
> CXX='g++'
> GCCGO='gccgo'
> GO111MODULE='auto'
> GOAMD64='v1'
> GOARCH='amd64'
> GOAUTH='netrc'
> GOBIN=''
> GOCACHE='/syzkaller/.cache/go-build'
> GOCACHEPROG=''
> GODEBUG=''
> GOENV='/syzkaller/.config/go/env'
> GOEXE=''
> GOEXPERIMENT=''
> GOFIPS140='off'
> GOFLAGS=''
> GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build4123752491=/tmp/go-build -gno-record-gcc-switches'
> GOHOSTARCH='amd64'
> GOHOSTOS='linux'
> GOINSECURE=''
> GOMOD='/syzkaller/jobs/linux/gopath/src/github.com/google/syzkaller/go.mod'
> GOMODCACHE='/syzkaller/jobs/linux/gopath/pkg/mod'
> GONOPROXY=''
> GONOSUMDB=''
> GOOS='linux'
> GOPATH='/syzkaller/jobs/linux/gopath'
> GOPRIVATE=''
> GOPROXY='https://proxy.golang.org,direct'
> GOROOT='/usr/local/go'
> GOSUMDB='sum.golang.org'
> GOTELEMETRY='local'
> GOTELEMETRYDIR='/syzkaller/.config/go/telemetry'
> GOTMPDIR=''
> GOTOOLCHAIN='auto'
> GOTOOLDIR='/usr/local/go/pkg/tool/linux_amd64'
> GOVCS=''
> GOVERSION='go1.26.0'
> GOWORK=''
> PKG_CONFIG='pkg-config'
> 
> git status (err=<nil>)
> HEAD detached at 5be7a9deb87
> nothing to commit, working tree clean
> 
> 
> tput: No value for $TERM and no -T specified
> tput: No value for $TERM and no -T specified
> Makefile:31: run command via tools/syz-env for best compatibility, see:
> Makefile:32: https://github.com/google/syzkaller/blob/master/docs/contributing.md#using-syz-env
> go list -f '{{.Stale}}' -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=5be7a9deb87612d05fcc86125226d72bc2297875 -X github.com/google/syzkaller/prog.gitRevisionDate=20260417-202028"  ./sys/syz-sysgen | grep -q false || go install -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=5be7a9deb87612d05fcc86125226d72bc2297875 -X github.com/google/syzkaller/prog.gitRevisionDate=20260417-202028"  ./sys/syz-sysgen
> make .descriptions
> tput: No value for $TERM and no -T specified
> tput: No value for $TERM and no -T specified
> Makefile:31: run command via tools/syz-env for best compatibility, see:
> Makefile:32: https://github.com/google/syzkaller/blob/master/docs/contributing.md#using-syz-env
> bin/syz-sysgen
> touch .descriptions
> GOOS=linux GOARCH=amd64 go build -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=5be7a9deb87612d05fcc86125226d72bc2297875 -X github.com/google/syzkaller/prog.gitRevisionDate=20260417-202028"  -o ./bin/linux_amd64/syz-execprog github.com/google/syzkaller/tools/syz-execprog
> mkdir -p ./bin/linux_amd64
> g++ -o ./bin/linux_amd64/syz-executor executor/executor.cc \
> 	-m64 -O2 -pthread -Wall -Werror -Wparentheses -Wunused-const-variable -Wframe-larger-than=16384 -Wno-stringop-overflow -Wno-array-bounds -Wno-format-overflow -Wno-unused-but-set-variable -Wno-unused-command-line-argument -static-pie -std=c++17 -I. -Iexecutor/_include   -DGOOS_linux=1 -DGOARCH_amd64=1 \
> 	-DHOSTGOOS_linux=1 -DGIT_REVISION=\"5be7a9deb87612d05fcc86125226d72bc2297875\"
> /usr/bin/ld: /tmp/ccUDlBPa.o: in function `Connection::Connect(char const*, char const*)':
> executor.cc:(.text._ZN10Connection7ConnectEPKcS1_[_ZN10Connection7ConnectEPKcS1_]+0x386): warning: Using 'gethostbyname' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
> ./tools/check-syzos.sh 2>/dev/null
> 
> 
> 
> Tested on:
> 
> commit:         4ee64205 Merge tag 'clk-for-linus' of git://git.kernel..
> git tree:       upstream
> kernel config:  https://syzkaller.appspot.com/x/.config?x=95ee3fe1c5a8ab57
> dashboard link: https://syzkaller.appspot.com/bug?extid=6985cb8e543ea90ba8ee
> compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
> patch:          https://syzkaller.appspot.com/x/patch.diff?x=122eb4ce580000
>