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:

if you depend on this functionality.
[   45.821207][   T31] wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[   45.829090][   T31] wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50
[   45.881225][   T31] wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[   45.889807][   T31] wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
[   45.956122][ T5884] chnl_net:caif_netlink_parms(): no params data found
[   46.001794][ T5884] bridge0: port 1(bridge_slave_0) entered blocking state
[   46.008977][ T5884] bridge0: port 1(bridge_slave_0) entered disabled state
[   46.016232][ T5884] bridge_slave_0: entered allmulticast mode
[   46.022616][ T5884] bridge_slave_0: entered promiscuous mode
[   46.035205][ T5884] bridge0: port 2(bridge_slave_1) entered blocking state
[   46.042381][ T5884] bridge0: port 2(bridge_slave_1) entered disabled state
[   46.053377][ T5884] bridge_slave_1: entered allmulticast mode
[   46.059638][ T5884] bridge_slave_1: entered promiscuous mode
[   46.071403][ T5884] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
[   46.081415][ T5884] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link
[   46.095160][ T5884] team0: Port device team_slave_0 added
[   46.101434][ T5884] team0: Port device team_slave_1 added
[   46.110592][ T5884] batman_adv: batadv0: Adding interface: batadv_slave_0
[   46.117771][ T5884] 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.
[   46.143797][ T5884] batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active
[   46.156685][ T5884] batman_adv: batadv0: Adding interface: batadv_slave_1
[   46.163621][ T5884] 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.
[   46.189517][ T5884] batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
[   46.206156][ T5884] hsr_slave_0: entered promiscuous mode
[   46.211900][ T5884] hsr_slave_1: entered promiscuous mode
[   46.241105][ T5884] netdevsim netdevsim2 netdevsim0: renamed from eth0
[   46.249140][ T5884] netdevsim netdevsim2 netdevsim1: renamed from eth1
[   46.257221][ T5884] netdevsim netdevsim2 netdevsim2: renamed from eth2
[   46.264770][ T5884] netdevsim netdevsim2 netdevsim3: renamed from eth3
[   46.276497][ T5884] bridge0: port 2(bridge_slave_1) entered blocking state
[   46.283532][ T5884] bridge0: port 2(bridge_slave_1) entered forwarding state
[   46.290811][ T5884] bridge0: port 1(bridge_slave_0) entered blocking state
[   46.297848][ T5884] bridge0: port 1(bridge_slave_0) entered forwarding state
[   46.316050][ T5884] 8021q: adding VLAN 0 to HW filter on device bond0
[   46.325293][ T3579] bridge0: port 1(bridge_slave_0) entered disabled state
[   46.332550][ T3579] bridge0: port 2(bridge_slave_1) entered disabled state
[   46.341998][ T5884] 8021q: adding VLAN 0 to HW filter on device team0
[   46.350374][ T1114] bridge0: port 1(bridge_slave_0) entered blocking state
[   46.357414][ T1114] bridge0: port 1(bridge_slave_0) entered forwarding state
[   46.366267][ T3579] bridge0: port 2(bridge_slave_1) entered blocking state
[   46.373305][ T3579] bridge0: port 2(bridge_slave_1) entered forwarding state
[   46.413150][ T5884] 8021q: adding VLAN 0 to HW filter on device batadv0
[   46.428418][ T5884] veth0_vlan: entered promiscuous mode
[   46.435468][ T5884] veth1_vlan: entered promiscuous mode
[   46.446016][ T5884] veth0_macvtap: entered promiscuous mode
[   46.452649][ T5884] veth1_macvtap: entered promiscuous mode
2026/02/04 12:06:36 executed programs: 0
[   46.461883][ T5884] batman_adv: batadv0: Interface activated: batadv_slave_0
[   46.470956][ T5884] batman_adv: batadv0: Interface activated: batadv_slave_1
[   46.480049][ T1114] netdevsim netdevsim2 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
[   46.488812][ T1114] netdevsim netdevsim2 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
[   46.497918][ T1114] netdevsim netdevsim2 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
[   46.508096][ T4665] netdevsim netdevsim2 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
[   46.549979][   T50] Bluetooth: hci0: unexpected cc 0x0c03 length: 249 > 1
[   46.557068][   T50] Bluetooth: hci0: unexpected cc 0x1003 length: 249 > 9
[   46.564078][   T50] Bluetooth: hci0: unexpected cc 0x1001 length: 249 > 9
[   46.571338][   T50] Bluetooth: hci0: unexpected cc 0x0c23 length: 249 > 4
[   46.579355][   T50] Bluetooth: hci0: unexpected cc 0x0c38 length: 249 > 2
[   46.614569][ T5926] chnl_net:caif_netlink_parms(): no params data found
[   46.633881][ T5926] bridge0: port 1(bridge_slave_0) entered blocking state
[   46.641080][ T5926] bridge0: port 1(bridge_slave_0) entered disabled state
[   46.648578][ T5926] bridge_slave_0: entered allmulticast mode
[   46.654971][ T5926] bridge_slave_0: entered promiscuous mode
[   46.663809][ T5926] bridge0: port 2(bridge_slave_1) entered blocking state
[   46.671026][ T5926] bridge0: port 2(bridge_slave_1) entered disabled state
[   46.678273][ T5926] bridge_slave_1: entered allmulticast mode
[   46.684428][ T5926] bridge_slave_1: entered promiscuous mode
[   46.695255][ T5926] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
[   46.705763][ T5926] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link
[   46.718720][ T5926] team0: Port device team_slave_0 added
[   46.725342][ T5926] team0: Port device team_slave_1 added
[   46.734410][ T5926] batman_adv: batadv0: Adding interface: batadv_slave_0
[   46.741923][ T5926] 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.
[   46.768097][ T5926] batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active
[   46.779874][ T5926] batman_adv: batadv0: Adding interface: batadv_slave_1
[   46.786899][ T5926] 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.
[   46.813288][ T5926] batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
[   46.831416][ T5926] hsr_slave_0: entered promiscuous mode
[   46.837206][ T5926] hsr_slave_1: entered promiscuous mode
[   46.842860][ T5926] debugfs: 'hsr0' already exists in 'hsr'
[   46.848803][ T5926] Cannot create hsr debugfs directory
[   46.876513][ T5926] netdevsim netdevsim0 netdevsim0: renamed from eth0
[   46.884169][ T5926] netdevsim netdevsim0 netdevsim1: renamed from eth1
[   46.891891][ T5926] netdevsim netdevsim0 netdevsim2: renamed from eth2
[   46.899508][ T5926] netdevsim netdevsim0 netdevsim3: renamed from eth3
[   46.921123][ T5926] 8021q: adding VLAN 0 to HW filter on device bond0
[   46.931215][ T5926] 8021q: adding VLAN 0 to HW filter on device team0
[   46.939622][ T4665] bridge0: port 1(bridge_slave_0) entered blocking state
[   46.946671][ T4665] bridge0: port 1(bridge_slave_0) entered forwarding state
[   46.956230][ T4665] bridge0: port 2(bridge_slave_1) entered blocking state
[   46.963273][ T4665] bridge0: port 2(bridge_slave_1) entered forwarding state
[   47.003047][ T5926] 8021q: adding VLAN 0 to HW filter on device batadv0
[   47.018146][ T5926] veth0_vlan: entered promiscuous mode
[   47.025562][ T5926] veth1_vlan: entered promiscuous mode
[   47.036300][ T5926] veth0_macvtap: entered promiscuous mode
[   47.043136][ T5926] veth1_macvtap: entered promiscuous mode
[   47.051969][ T5926] batman_adv: batadv0: Interface activated: batadv_slave_0
[   47.061005][ T5926] batman_adv: batadv0: Interface activated: batadv_slave_1
[   47.070249][ T1114] netdevsim netdevsim0 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
[   47.079284][ T1114] netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
[   47.088526][ T1114] netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
[   47.097604][ T1114] netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
[   47.118491][ T1114] wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[   47.128034][ T1114] wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50
[   47.138641][   T31] wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[   47.146575][   T31] wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
[   47.397443][ T4665] netdevsim netdevsim2 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   48.656190][ T4665] netdevsim netdevsim2 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   50.135817][ T4665] netdevsim netdevsim2 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   50.196037][ T4665] netdevsim netdevsim2 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   50.267780][ T4665] bridge_slave_1: left allmulticast mode
[   50.273424][ T4665] bridge_slave_1: left promiscuous mode
[   50.279147][ T4665] bridge0: port 2(bridge_slave_1) entered disabled state
[   50.286608][ T4665] bridge_slave_0: left allmulticast mode
[   50.292223][ T4665] bridge_slave_0: left promiscuous mode
[   50.297940][ T4665] bridge0: port 1(bridge_slave_0) entered disabled state
[   50.346523][ T4665] bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
[   50.355730][ T4665] bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
[   50.364635][ T4665] bond0 (unregistering): Released all slaves
[   50.489243][ T4665] hsr_slave_0: left promiscuous mode
[   50.495116][ T4665] hsr_slave_1: left promiscuous mode
[   50.500603][ T4665] batman_adv: batadv0: Interface deactivated: batadv_slave_0
[   50.508254][ T4665] batman_adv: batadv0: Removing interface: batadv_slave_0
[   50.516362][ T4665] batman_adv: batadv0: Interface deactivated: batadv_slave_1
[   50.523830][ T4665] batman_adv: batadv0: Removing interface: batadv_slave_1
[   50.532141][ T4665] veth1_macvtap: left promiscuous mode
[   50.537663][ T4665] veth0_macvtap: left promiscuous mode
[   50.543134][ T4665] veth1_vlan: left promiscuous mode
[   50.548371][ T4665] veth0_vlan: left promiscuous mode
[   50.572434][ T4665] team0 (unregistering): Port device team_slave_1 removed
[   50.580735][ T4665] team0 (unregistering): Port device team_slave_0 removed
[   50.796895][ T4665] netdevsim netdevsim0 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   50.995743][ T4665] netdevsim netdevsim0 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   51.046021][ T4665] netdevsim netdevsim0 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   51.086321][ T4665] netdevsim netdevsim0 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   51.168169][ T4665] bridge_slave_1: left allmulticast mode
[   51.173821][ T4665] bridge_slave_1: left promiscuous mode
[   51.179500][ T4665] bridge0: port 2(bridge_slave_1) entered disabled state
[   51.187423][ T4665] bridge_slave_0: left allmulticast mode
[   51.193142][ T4665] bridge_slave_0: left promiscuous mode
[   51.198820][ T4665] bridge0: port 1(bridge_slave_0) entered disabled state
[   51.227199][ T4665] bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
[   51.236439][ T4665] bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
[   51.245559][ T4665] bond0 (unregistering): Released all slaves
[   51.397225][ T4665] hsr_slave_0: left promiscuous mode
[   51.402817][ T4665] hsr_slave_1: left promiscuous mode
[   51.408550][ T4665] batman_adv: batadv0: Interface deactivated: batadv_slave_0
[   51.416235][ T4665] batman_adv: batadv0: Removing interface: batadv_slave_0
[   51.423612][ T4665] batman_adv: batadv0: Interface deactivated: batadv_slave_1
[   51.431463][ T4665] batman_adv: batadv0: Removing interface: batadv_slave_1
[   51.440527][ T4665] veth1_macvtap: left promiscuous mode
[   51.446063][ T4665] veth0_macvtap: left promiscuous mode
[   51.451569][ T4665] veth1_vlan: left promiscuous mode
[   51.456836][ T4665] veth0_vlan: left promiscuous mode
[   51.490937][ T4665] team0 (unregistering): Port device team_slave_1 removed
[   51.500524][ T4665] 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-build3894858430=/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 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/ccQZz4bN.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=14a787fa580000


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.