Re: [syzbot] [fs?] WARNING in nsproxy_ns_active_put

[syzbot <syzbot+0b2e79f91ff6579bfa5b@syzkaller.appspotmail.com>]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

SYZFAIL: failed to recv rpc

SYZFAIL: failed to recv rpc


Warning: Permanently added '10.128.1.29' (ED25519) to the list of known hosts.
2025/11/11 11:01:12 parsed 1 programs
[   92.366829][  T894] cfg80211: failed to load regulatory.db
[   94.101317][ T5831] cgroup: Unknown subsys name 'net'
[   94.208868][ T5831] cgroup: Unknown subsys name 'cpuset'
[   94.218695][ T5831] cgroup: Unknown subsys name 'rlimit'
Setting up swapspace version 1, size = 127995904 bytes
[   95.913996][ T5831] Adding 124996k swap on ./swap-file.  Priority:0 extents:1 across:124996k 
[   99.210494][ T5845] soft_limit_in_bytes is deprecated and will be removed. Please report your usecase to linux-mm@kvack.org if you depend on this functionality.
[   99.368014][   T52] Bluetooth: hci0: unexpected cc 0x0c03 length: 249 > 1
[   99.376801][   T52] Bluetooth: hci0: unexpected cc 0x1003 length: 249 > 9
[   99.385991][   T52] Bluetooth: hci0: unexpected cc 0x1001 length: 249 > 9
[   99.394090][   T52] Bluetooth: hci0: unexpected cc 0x0c23 length: 249 > 4
[   99.403295][   T52] Bluetooth: hci0: unexpected cc 0x0c38 length: 249 > 2
[   99.760048][   T67] wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[   99.769465][   T67] wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50
[   99.812956][   T13] wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[   99.820978][   T13] wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
[  101.094305][ T5880] chnl_net:caif_netlink_parms(): no params data found
[  101.244059][ T5880] bridge0: port 1(bridge_slave_0) entered blocking state
[  101.252746][ T5880] bridge0: port 1(bridge_slave_0) entered disabled state
[  101.261818][ T5880] bridge_slave_0: entered allmulticast mode
[  101.270392][ T5880] bridge_slave_0: entered promiscuous mode
[  101.283473][ T5880] bridge0: port 2(bridge_slave_1) entered blocking state
[  101.291198][ T5880] bridge0: port 2(bridge_slave_1) entered disabled state
[  101.298667][ T5880] bridge_slave_1: entered allmulticast mode
[  101.307108][ T5880] bridge_slave_1: entered promiscuous mode
[  101.360560][ T5880] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
[  101.373330][ T5880] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link
[  101.413565][ T5880] team0: Port device team_slave_0 added
[  101.422832][ T5880] team0: Port device team_slave_1 added
[  101.463069][ T5880] batman_adv: batadv0: Adding interface: batadv_slave_0
[  101.470261][ T5880] batman_adv: batadv0: The MTU of interface batadv_slave_0 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1532 would solve the problem.
[  101.497282][ T5880] batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active
[  101.511788][ T5880] batman_adv: batadv0: Adding interface: batadv_slave_1
[  101.518889][ T5880] batman_adv: batadv0: The MTU of interface batadv_slave_1 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1532 would solve the problem.
[  101.545058][ T5880] batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
[  101.590841][ T5880] hsr_slave_0: entered promiscuous mode
[  101.597434][ T5880] hsr_slave_1: entered promiscuous mode
[  101.741572][ T5880] netdevsim netdevsim0 netdevsim0: renamed from eth0
[  101.754163][ T5880] netdevsim netdevsim0 netdevsim1: renamed from eth1
[  101.764799][ T5880] netdevsim netdevsim0 netdevsim2: renamed from eth2
[  101.774770][ T5880] netdevsim netdevsim0 netdevsim3: renamed from eth3
[  101.805511][ T5880] bridge0: port 2(bridge_slave_1) entered blocking state
[  101.812788][ T5880] bridge0: port 2(bridge_slave_1) entered forwarding state
[  101.820983][ T5880] bridge0: port 1(bridge_slave_0) entered blocking state
[  101.828371][ T5880] bridge0: port 1(bridge_slave_0) entered forwarding state
[  101.843110][   T13] bridge0: port 1(bridge_slave_0) entered disabled state
[  101.851795][   T13] bridge0: port 2(bridge_slave_1) entered disabled state
[  101.904027][ T5880] 8021q: adding VLAN 0 to HW filter on device bond0
[  101.928006][ T5880] 8021q: adding VLAN 0 to HW filter on device team0
[  101.942529][ T3448] bridge0: port 1(bridge_slave_0) entered blocking state
[  101.950392][ T3448] bridge0: port 1(bridge_slave_0) entered forwarding state
[  101.964563][   T13] bridge0: port 2(bridge_slave_1) entered blocking state
[  101.971799][   T13] bridge0: port 2(bridge_slave_1) entered forwarding state
[  102.152983][ T5880] 8021q: adding VLAN 0 to HW filter on device batadv0
[  102.197805][ T5880] veth0_vlan: entered promiscuous mode
[  102.210102][ T5880] veth1_vlan: entered promiscuous mode
[  102.244663][ T5880] veth0_macvtap: entered promiscuous mode
[  102.254634][ T5880] veth1_macvtap: entered promiscuous mode
[  102.273656][ T5880] batman_adv: batadv0: Interface activated: batadv_slave_0
[  102.289496][ T5880] batman_adv: batadv0: Interface activated: batadv_slave_1
[  102.304731][   T67] netdevsim netdevsim0 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
[  102.314238][   T67] netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
[  102.324278][   T67] netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
[  102.334159][   T67] netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
[  102.469673][   T67] netdevsim netdevsim0 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[  102.543054][   T67] netdevsim netdevsim0 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[  102.622429][   T67] netdevsim netdevsim0 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[  102.698368][   T67] netdevsim netdevsim0 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
2025/11/11 11:01:26 executed programs: 0
[  104.788606][   T52] Bluetooth: hci0: unexpected cc 0x0c03 length: 249 > 1
[  104.799432][   T52] Bluetooth: hci0: unexpected cc 0x1003 length: 249 > 9
[  104.807512][   T52] Bluetooth: hci0: unexpected cc 0x1001 length: 249 > 9
[  104.816410][   T52] Bluetooth: hci0: unexpected cc 0x0c23 length: 249 > 4
[  104.824560][   T52] Bluetooth: hci0: unexpected cc 0x0c38 length: 249 > 2
[  104.982601][ T5940] chnl_net:caif_netlink_parms(): no params data found
[  105.059249][ T5940] bridge0: port 1(bridge_slave_0) entered blocking state
[  105.066542][ T5940] bridge0: port 1(bridge_slave_0) entered disabled state
[  105.073685][ T5940] bridge_slave_0: entered allmulticast mode
[  105.081124][ T5940] bridge_slave_0: entered promiscuous mode
[  105.089124][ T5940] bridge0: port 2(bridge_slave_1) entered blocking state
[  105.096583][ T5940] bridge0: port 2(bridge_slave_1) entered disabled state
[  105.104018][ T5940] bridge_slave_1: entered allmulticast mode
[  105.111771][ T5940] bridge_slave_1: entered promiscuous mode
[  105.143334][ T5940] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
[  105.155734][ T5940] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link
[  105.191407][ T5940] team0: Port device team_slave_0 added
[  105.201031][ T5940] team0: Port device team_slave_1 added
[  105.235802][ T5940] batman_adv: batadv0: Adding interface: batadv_slave_0
[  105.242802][ T5940] batman_adv: batadv0: The MTU of interface batadv_slave_0 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1532 would solve the problem.
[  105.269608][ T5940] batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active
[  105.296300][ T5940] batman_adv: batadv0: Adding interface: batadv_slave_1
[  105.303516][ T5940] batman_adv: batadv0: The MTU of interface batadv_slave_1 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1532 would solve the problem.
[  105.331738][ T5940] batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
[  105.417552][ T5940] hsr_slave_0: entered promiscuous mode
[  105.424204][ T5940] hsr_slave_1: entered promiscuous mode
[  105.430828][ T5940] debugfs: 'hsr0' already exists in 'hsr'
[  105.437317][ T5940] Cannot create hsr debugfs directory
[  105.454873][   T67] bridge_slave_1: left allmulticast mode
[  105.460813][   T67] bridge_slave_1: left promiscuous mode
[  105.467853][   T67] bridge0: port 2(bridge_slave_1) entered disabled state
[  105.479304][   T67] bridge_slave_0: left allmulticast mode
[  105.485065][   T67] bridge_slave_0: left promiscuous mode
[  105.491001][   T67] bridge0: port 1(bridge_slave_0) entered disabled state
[  105.729562][   T67] bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
[  105.741503][   T67] bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
[  105.752583][   T67] bond0 (unregistering): Released all slaves
[  105.835828][   T67] hsr_slave_0: left promiscuous mode
[  105.842862][   T67] hsr_slave_1: left promiscuous mode
[  105.849433][   T67] batman_adv: batadv0: Interface deactivated: batadv_slave_0
[  105.857469][   T67] batman_adv: batadv0: Removing interface: batadv_slave_0
[  105.865850][   T67] batman_adv: batadv0: Interface deactivated: batadv_slave_1
[  105.873344][   T67] batman_adv: batadv0: Removing interface: batadv_slave_1
[  105.890846][   T67] veth1_macvtap: left promiscuous mode
[  105.897610][   T67] veth0_macvtap: left promiscuous mode
[  105.903553][   T67] veth1_vlan: left promiscuous mode
[  105.910171][   T67] veth0_vlan: left promiscuous mode
[  106.222498][   T67] team0 (unregistering): Port device team_slave_1 removed
[  106.255035][   T67] team0 (unregistering): Port device team_slave_0 removed
[  106.849861][   T52] Bluetooth: hci0: command tx timeout
[  107.366951][ T5940] netdevsim netdevsim0 netdevsim0: renamed from eth0
[  107.390747][ T5940] netdevsim netdevsim0 netdevsim1: renamed from eth1
[  107.409101][ T5940] netdevsim netdevsim0 netdevsim2: renamed from eth2
[  107.429220][ T5940] netdevsim netdevsim0 netdevsim3: renamed from eth3
[  107.687917][ T5940] 8021q: adding VLAN 0 to HW filter on device bond0
[  107.729157][ T5940] 8021q: adding VLAN 0 to HW filter on device team0
[  107.757652][ T1309] bridge0: port 1(bridge_slave_0) entered blocking state
[  107.764863][ T1309] bridge0: port 1(bridge_slave_0) entered forwarding state
[  107.814393][ T1309] bridge0: port 2(bridge_slave_1) entered blocking state
[  107.821819][ T1309] bridge0: port 2(bridge_slave_1) entered forwarding state
[  108.188295][ T5940] 8021q: adding VLAN 0 to HW filter on device batadv0
[  108.234481][ T5940] veth0_vlan: entered promiscuous mode
[  108.246943][ T5940] veth1_vlan: entered promiscuous mode
[  108.277479][ T5940] veth0_macvtap: entered promiscuous mode
[  108.288108][ T5940] veth1_macvtap: entered promiscuous mode
[  108.306578][ T5940] batman_adv: batadv0: Interface activated: batadv_slave_0
[  108.321859][ T5940] batman_adv: batadv0: Interface activated: batadv_slave_1
[  108.336901][ T1322] netdevsim netdevsim0 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
[  108.346834][ T1322] netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
[  108.358941][ T1322] netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
[  108.368475][ T1322] netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
[  108.430497][ T1309] wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[  108.438794][ T1309] wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50
[  108.474331][   T67] wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[  108.484170][   T67] wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
SYZFAIL: failed to recv rpc


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-build3388558029=/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='go1.24.4'
GOWORK=''
PKG_CONFIG='pkg-config'

git status (err=<nil>)
HEAD detached at 4e1406b4def
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=4e1406b4defac0e2a9d9424c70706f79a7750cf3 -X github.com/google/syzkaller/prog.gitRevisionDate=20251106-151142"  ./sys/syz-sysgen | grep -q false || go install -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=4e1406b4defac0e2a9d9424c70706f79a7750cf3 -X github.com/google/syzkaller/prog.gitRevisionDate=20251106-151142"  ./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=4e1406b4defac0e2a9d9424c70706f79a7750cf3 -X github.com/google/syzkaller/prog.gitRevisionDate=20251106-151142"  -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=\"4e1406b4defac0e2a9d9424c70706f79a7750cf3\"
/usr/bin/ld: /tmp/ccimHo7N.o: in function `Connection::Connect(char const*, char const*)':
executor.cc:(.text._ZN10Connection7ConnectEPKcS1_[_ZN10Connection7ConnectEPKcS1_]+0x104): 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:         ae901e5e Merge patch series "ns: fixes for namespace i..
git tree:       https://github.com/brauner/linux.git namespace-6.19.fixes
kernel config:  https://syzkaller.appspot.com/x/.config?x=7b0bf36f88602817
dashboard link: https://syzkaller.appspot.com/bug?extid=0b2e79f91ff6579bfa5b
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Note: no patches were applied.