Re: [syzbot] [gfs2?] memory leak in __kthread_create_on_node

[syzbot <syzbot+aac438d7a1c44071e04b@syzkaller.appspotmail.com>]

Hello,

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

: port 1(bridge_slave_0) entered blocking state
[   49.569526][ T5894] bridge0: port 1(bridge_slave_0) entered disabled state
[   49.577272][ T5894] bridge_slave_0: entered allmulticast mode
[   49.583706][ T5894] bridge_slave_0: entered promiscuous mode
[   49.596953][ T5894] bridge0: port 2(bridge_slave_1) entered blocking state
[   49.604391][ T5894] bridge0: port 2(bridge_slave_1) entered disabled state
[   49.611600][ T5894] bridge_slave_1: entered allmulticast mode
[   49.618015][ T5894] bridge_slave_1: entered promiscuous mode
[   49.628063][ T5894] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
[   49.638158][ T5894] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link
[   49.651127][ T5894] team0: Port device team_slave_0 added
[   49.657258][ T5894] team0: Port device team_slave_1 added
[   49.666478][ T5894] batman_adv: batadv0: Adding interface: batadv_slave_0
[   49.673408][ T5894] 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.
[   49.699306][ T5894] batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active
[   49.710247][ T5894] batman_adv: batadv0: Adding interface: batadv_slave_1
[   49.717331][ T5894] 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.
[   49.743223][ T5894] batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
[   49.761247][ T5894] hsr_slave_0: entered promiscuous mode
[   49.767053][ T5894] hsr_slave_1: entered promiscuous mode
[   49.796552][ T5894] netdevsim netdevsim5 netdevsim0: renamed from eth0
[   49.806103][ T5894] netdevsim netdevsim5 netdevsim1: renamed from eth1
[   49.813706][ T5894] netdevsim netdevsim5 netdevsim2: renamed from eth2
[   49.821484][ T5894] netdevsim netdevsim5 netdevsim3: renamed from eth3
[   49.833675][ T5894] bridge0: port 2(bridge_slave_1) entered blocking state
[   49.840885][ T5894] bridge0: port 2(bridge_slave_1) entered forwarding state
[   49.848233][ T5894] bridge0: port 1(bridge_slave_0) entered blocking state
[   49.855361][ T5894] bridge0: port 1(bridge_slave_0) entered forwarding state
[   49.874093][ T5894] 8021q: adding VLAN 0 to HW filter on device bond0
[   49.883306][   T31] bridge0: port 1(bridge_slave_0) entered disabled state
[   49.890757][   T31] bridge0: port 2(bridge_slave_1) entered disabled state
[   49.899998][ T5894] 8021q: adding VLAN 0 to HW filter on device team0
[   49.908475][ T4273] bridge0: port 1(bridge_slave_0) entered blocking state
[   49.915629][ T4273] bridge0: port 1(bridge_slave_0) entered forwarding state
[   49.926439][   T31] bridge0: port 2(bridge_slave_1) entered blocking state
[   49.933487][   T31] bridge0: port 2(bridge_slave_1) entered forwarding state
[   49.976870][ T5894] 8021q: adding VLAN 0 to HW filter on device batadv0
[   50.019341][ T5894] veth0_vlan: entered promiscuous mode
[   50.027485][ T5894] veth1_vlan: entered promiscuous mode
[   50.037907][ T5894] veth0_macvtap: entered promiscuous mode
[   50.045065][ T5894] veth1_macvtap: entered promiscuous mode
[   50.053367][ T5894] batman_adv: batadv0: Interface activated: batadv_slave_0
[   50.062517][ T5894] batman_adv: batadv0: Interface activated: batadv_slave_1
2026/02/03 13:34:00 executed programs: 0
[   50.071587][   T31] netdevsim netdevsim5 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
[   50.080766][   T31] netdevsim netdevsim5 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
[   50.089873][   T31] netdevsim netdevsim5 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
[   50.098962][   T31] netdevsim netdevsim5 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
[   50.146631][   T51] Bluetooth: hci0: unexpected cc 0x0c03 length: 249 > 1
[   50.153698][   T51] Bluetooth: hci0: unexpected cc 0x1003 length: 249 > 9
[   50.161549][   T51] Bluetooth: hci0: unexpected cc 0x1001 length: 249 > 9
[   50.169537][   T51] Bluetooth: hci0: unexpected cc 0x0c23 length: 249 > 4
[   50.176954][   T51] Bluetooth: hci0: unexpected cc 0x0c38 length: 249 > 2
[   50.211055][ T5935] chnl_net:caif_netlink_parms(): no params data found
[   50.232507][ T5935] bridge0: port 1(bridge_slave_0) entered blocking state
[   50.239849][ T5935] bridge0: port 1(bridge_slave_0) entered disabled state
[   50.247221][ T5935] bridge_slave_0: entered allmulticast mode
[   50.253454][ T5935] bridge_slave_0: entered promiscuous mode
[   50.260028][ T5935] bridge0: port 2(bridge_slave_1) entered blocking state
[   50.267129][ T5935] bridge0: port 2(bridge_slave_1) entered disabled state
[   50.274406][ T5935] bridge_slave_1: entered allmulticast mode
[   50.280561][ T5935] bridge_slave_1: entered promiscuous mode
[   50.291387][ T5935] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
[   50.301433][ T5935] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link
[   50.315273][ T5935] team0: Port device team_slave_0 added
[   50.321623][ T5935] team0: Port device team_slave_1 added
[   50.331276][ T5935] batman_adv: batadv0: Adding interface: batadv_slave_0
[   50.338331][ T5935] 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.
[   50.364309][ T5935] batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active
[   50.375554][ T5935] batman_adv: batadv0: Adding interface: batadv_slave_1
[   50.382485][ T5935] 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.
[   50.408696][ T5935] batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
[   50.426057][ T5935] hsr_slave_0: entered promiscuous mode
[   50.431913][ T5935] hsr_slave_1: entered promiscuous mode
[   50.437731][ T5935] debugfs: 'hsr0' already exists in 'hsr'
[   50.443458][ T5935] Cannot create hsr debugfs directory
[   50.471333][ T5935] netdevsim netdevsim0 netdevsim0: renamed from eth0
[   50.479234][ T5935] netdevsim netdevsim0 netdevsim1: renamed from eth1
[   50.486892][ T5935] netdevsim netdevsim0 netdevsim2: renamed from eth2
[   50.494636][ T5935] netdevsim netdevsim0 netdevsim3: renamed from eth3
[   50.506883][ T5935] bridge0: port 2(bridge_slave_1) entered blocking state
[   50.513937][ T5935] bridge0: port 2(bridge_slave_1) entered forwarding state
[   50.521151][ T5935] bridge0: port 1(bridge_slave_0) entered blocking state
[   50.528314][ T5935] bridge0: port 1(bridge_slave_0) entered forwarding state
[   50.546104][ T5935] 8021q: adding VLAN 0 to HW filter on device bond0
[   50.555923][ T1028] bridge0: port 1(bridge_slave_0) entered disabled state
[   50.563234][ T1028] bridge0: port 2(bridge_slave_1) entered disabled state
[   50.572397][ T5935] 8021q: adding VLAN 0 to HW filter on device team0
[   50.580932][ T4273] bridge0: port 1(bridge_slave_0) entered blocking state
[   50.587999][ T4273] bridge0: port 1(bridge_slave_0) entered forwarding state
[   50.597473][ T1028] bridge0: port 2(bridge_slave_1) entered blocking state
[   50.604528][ T1028] bridge0: port 2(bridge_slave_1) entered forwarding state
[   50.647463][ T5935] 8021q: adding VLAN 0 to HW filter on device batadv0
[   50.662929][ T5935] veth0_vlan: entered promiscuous mode
[   50.670959][ T5935] veth1_vlan: entered promiscuous mode
[   50.681606][ T5935] veth0_macvtap: entered promiscuous mode
[   50.688740][ T5935] veth1_macvtap: entered promiscuous mode
[   50.697748][ T5935] batman_adv: batadv0: Interface activated: batadv_slave_0
[   50.707515][ T5935] batman_adv: batadv0: Interface activated: batadv_slave_1
[   50.716544][ T4273] netdevsim netdevsim0 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
[   50.725515][ T4273] netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
[   50.734628][ T4273] netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
[   50.744542][ T4273] netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
[   50.762892][ T4273] wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[   50.771050][ T4273] wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50
[   50.781621][   T31] wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[   50.789850][   T31] wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
[   50.879037][   T31] netdevsim netdevsim5 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   50.915713][   T31] netdevsim netdevsim5 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   51.004863][   T31] netdevsim netdevsim5 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   51.074863][   T31] netdevsim netdevsim5 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   52.016178][   T31] bridge_slave_1: left allmulticast mode
[   52.021837][   T31] bridge_slave_1: left promiscuous mode
[   52.027571][   T31] bridge0: port 2(bridge_slave_1) entered disabled state
[   52.035331][   T31] bridge_slave_0: left allmulticast mode
[   52.040954][   T31] bridge_slave_0: left promiscuous mode
[   52.046653][   T31] bridge0: port 1(bridge_slave_0) entered disabled state
[   52.106207][   T31] bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
[   52.115467][   T31] bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
[   52.125163][   T31] bond0 (unregistering): Released all slaves
[   52.193847][   T31] hsr_slave_0: left promiscuous mode
[   52.200333][   T31] hsr_slave_1: left promiscuous mode
[   52.206079][   T31] batman_adv: batadv0: Interface deactivated: batadv_slave_0
[   52.213540][   T31] batman_adv: batadv0: Removing interface: batadv_slave_0
[   52.221223][   T31] batman_adv: batadv0: Interface deactivated: batadv_slave_1
[   52.228932][   T31] batman_adv: batadv0: Removing interface: batadv_slave_1
[   52.237267][   T31] veth1_macvtap: left promiscuous mode
[   52.242816][   T31] veth0_macvtap: left promiscuous mode
[   52.248610][   T31] veth1_vlan: left promiscuous mode
[   52.253921][   T31] veth0_vlan: left promiscuous mode
[   52.277608][   T31] team0 (unregistering): Port device team_slave_1 removed
[   52.286132][   T31] team0 (unregistering): Port device team_slave_0 removed
[   52.766136][ T1028] netdevsim netdevsim0 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   54.465080][ T1028] netdevsim netdevsim0 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   54.525147][ T1028] netdevsim netdevsim0 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   54.565331][ T1028] netdevsim netdevsim0 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   54.639649][ T1028] bridge_slave_1: left allmulticast mode
[   54.645358][ T1028] bridge_slave_1: left promiscuous mode
[   54.651032][ T1028] bridge0: port 2(bridge_slave_1) entered disabled state
[   54.658760][ T1028] bridge_slave_0: left allmulticast mode
[   54.664566][ T1028] bridge_slave_0: left promiscuous mode
[   54.670254][ T1028] bridge0: port 1(bridge_slave_0) entered disabled state
[   54.726139][ T1028] bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
[   54.735307][ T1028] bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
[   54.744759][ T1028] bond0 (unregistering): Released all slaves
[   54.858073][ T1028] hsr_slave_0: left promiscuous mode
[   54.865227][ T1028] hsr_slave_1: left promiscuous mode
[   54.870765][ T1028] batman_adv: batadv0: Interface deactivated: batadv_slave_0
[   54.878359][ T1028] batman_adv: batadv0: Removing interface: batadv_slave_0
[   54.886112][ T1028] batman_adv: batadv0: Interface deactivated: batadv_slave_1
[   54.893489][ T1028] batman_adv: batadv0: Removing interface: batadv_slave_1
[   54.903185][ T1028] veth1_macvtap: left promiscuous mode
[   54.908932][ T1028] veth0_macvtap: left promiscuous mode
[   54.914513][ T1028] veth1_vlan: left promiscuous mode
[   54.919924][ T1028] veth0_vlan: left promiscuous mode
[   54.943530][ T1028] team0 (unregistering): Port device team_slave_1 removed
[   54.952050][ T1028] team0 (unregistering): Port device team_slave_0 removed


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-build3933183977=/tmp/go-build -gno-record-gcc-switches'
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMOD='/syzkaller/jobs-2/linux/gopath/src/github.com/google/syzkaller/go.mod'
GOMODCACHE='/syzkaller/jobs-2/linux/gopath/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/syzkaller/jobs-2/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 b78a734197
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=b78a7341979245ec72840af68695cb23b98dc2cb -X github.com/google/syzkaller/prog.gitRevisionDate=20260128-224926"  ./sys/syz-sysgen | grep -q false || go install -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=b78a7341979245ec72840af68695cb23b98dc2cb -X github.com/google/syzkaller/prog.gitRevisionDate=20260128-224926"  ./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=b78a7341979245ec72840af68695cb23b98dc2cb -X github.com/google/syzkaller/prog.gitRevisionDate=20260128-224926"  -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=\"b78a7341979245ec72840af68695cb23b98dc2cb\"
/usr/bin/ld: /tmp/ccJgQDSd.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


Error text is too large and was truncated, full error text is at:
https://syzkaller.appspot.com/x/error.txt?x=10e0c402580000


Tested on:

commit:         da6f5bbc gfs2: fix memory leaks in gfs2_fill_super err..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2.git for-next
kernel config:  https://syzkaller.appspot.com/x/.config?x=9d7d0fbecb37bff8
dashboard link: https://syzkaller.appspot.com/bug?extid=aac438d7a1c44071e04b
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44

Note: no patches were applied.