Message-ID: <694a7508.050a0220.19928e.001f.GAE@google.com>
Date: Tue, 23 Dec 2025 02:55:04 -0800
From: syzbot <syzbot+9ca2c6e6b098bf5ae60a@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com, 
	wangjinchao600@...il.com
Subject: Re: [syzbot] [fs?] [mm?] WARNING in sched_mm_cid_fork

Hello,

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

pected cc 0x1003 length: 249 > 9
[  106.290104][ T4681] Bluetooth: hci0: unexpected cc 0x1001 length: 249 > 9
[  106.308631][ T4681] Bluetooth: hci0: unexpected cc 0x0c23 length: 249 > 4
[  106.312667][ T4681] Bluetooth: hci0: unexpected cc 0x0c38 length: 249 > 2
[  106.864566][ T3065] wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[  106.868107][ T3065] wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50
[  107.277164][  T798] wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[  107.289839][  T798] wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
[  107.319347][ T5348] bridge0: port 1(bridge_slave_0) entered blocking state
[  107.336348][ T5348] bridge0: port 1(bridge_slave_0) entered disabled state
[  107.346671][ T5348] bridge_slave_0: entered allmulticast mode
[  107.372525][ T5348] bridge_slave_0: entered promiscuous mode
[  107.407967][ T5348] bridge0: port 2(bridge_slave_1) entered blocking state
[  107.430975][ T5348] bridge0: port 2(bridge_slave_1) entered disabled state
[  107.434192][ T5348] bridge_slave_1: entered allmulticast mode
[  107.457072][ T5348] bridge_slave_1: entered promiscuous mode
[  107.574474][ T5348] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
[  107.606216][ T5348] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link
[  107.934909][ T5348] team0: Port device team_slave_0 added
[  107.973291][ T5348] team0: Port device team_slave_1 added
[  108.098501][ T5348] batman_adv: batadv0: Adding interface: batadv_slave_0
[  108.119869][ T5348] 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.
[  108.164963][ T5348] batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active
[  108.208171][ T5348] batman_adv: batadv0: Adding interface: batadv_slave_1
[  108.220177][ T5348] 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.
[  108.240398][ T5348] batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
[  108.331236][ T4681] Bluetooth: hci0: command tx timeout
[  108.460703][ T5348] hsr_slave_0: entered promiscuous mode
[  108.471221][ T5348] hsr_slave_1: entered promiscuous mode
[  108.993576][ T5348] netdevsim netdevsim3 netdevsim0: renamed from eth0
[  109.022778][ T5348] netdevsim netdevsim3 netdevsim1: renamed from eth1
[  109.043630][ T5348] netdevsim netdevsim3 netdevsim2: renamed from eth2
[  109.065659][ T5348] netdevsim netdevsim3 netdevsim3: renamed from eth3
[  109.280740][ T5348] 8021q: adding VLAN 0 to HW filter on device bond0
[  109.317063][ T5348] 8021q: adding VLAN 0 to HW filter on device team0
[  109.346111][ T2771] bridge0: port 1(bridge_slave_0) entered blocking state
[  109.349571][ T2771] bridge0: port 1(bridge_slave_0) entered forwarding state
[  109.393753][ T2771] bridge0: port 2(bridge_slave_1) entered blocking state
[  109.397101][ T2771] bridge0: port 2(bridge_slave_1) entered forwarding state
[  109.840375][ T5348] 8021q: adding VLAN 0 to HW filter on device batadv0
[  109.968037][ T5348] veth0_vlan: entered promiscuous mode
[  109.993170][ T5348] veth1_vlan: entered promiscuous mode
[  110.059216][ T5348] veth0_macvtap: entered promiscuous mode
[  110.082571][ T5348] veth1_macvtap: entered promiscuous mode
[  110.133386][ T5348] batman_adv: batadv0: Interface activated: batadv_slave_0
[  110.164418][ T5348] batman_adv: batadv0: Interface activated: batadv_slave_1
[  110.202014][  T798] netdevsim netdevsim3 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
[  110.212987][  T798] netdevsim netdevsim3 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
[  110.240778][  T798] netdevsim netdevsim3 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
[  110.255674][  T798] netdevsim netdevsim3 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
[  110.409808][ T4681] Bluetooth: hci0: command tx timeout
2025/12/23 10:54:07 executed programs: 0
[  111.503962][   T46] Bluetooth: hci1: unexpected cc 0x0c03 length: 249 > 1
[  111.508536][   T46] Bluetooth: hci1: unexpected cc 0x1003 length: 249 > 9
[  111.512966][   T46] Bluetooth: hci1: unexpected cc 0x1001 length: 249 > 9
[  111.517185][   T46] Bluetooth: hci1: unexpected cc 0x0c23 length: 249 > 4
[  111.522282][   T46] Bluetooth: hci1: unexpected cc 0x0c38 length: 249 > 2
[  111.845050][ T5448] chnl_net:caif_netlink_parms(): no params data found
[  112.075203][ T5448] bridge0: port 1(bridge_slave_0) entered blocking state
[  112.079877][ T5448] bridge0: port 1(bridge_slave_0) entered disabled state
[  112.083263][ T5448] bridge_slave_0: entered allmulticast mode
[  112.109691][ T5448] bridge_slave_0: entered promiscuous mode
[  112.121333][ T5448] bridge0: port 2(bridge_slave_1) entered blocking state
[  112.124549][ T5448] bridge0: port 2(bridge_slave_1) entered disabled state
[  112.127704][ T5448] bridge_slave_1: entered allmulticast mode
[  112.151002][ T5448] bridge_slave_1: entered promiscuous mode
[  112.202533][ T5448] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
[  112.210059][ T5448] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link
[  112.280707][ T5448] team0: Port device team_slave_0 added
[  112.301603][ T5448] team0: Port device team_slave_1 added
[  112.379815][ T5448] batman_adv: batadv0: Adding interface: batadv_slave_0
[  112.382812][ T5448] 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.
[  112.419626][ T5448] batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active
[  112.439776][ T5448] batman_adv: batadv0: Adding interface: batadv_slave_1
[  112.449981][ T5448] 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.
[  112.476348][ T5448] batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
[  112.489728][   T46] Bluetooth: hci0: command tx timeout
[  112.571680][ T5448] hsr_slave_0: entered promiscuous mode
[  112.590714][ T5448] hsr_slave_1: entered promiscuous mode
[  112.600495][ T5448] debugfs: 'hsr0' already exists in 'hsr'
[  112.604355][ T5448] Cannot create hsr debugfs directory
[  112.966802][ T5448] netdevsim netdevsim0 netdevsim0: renamed from eth0
[  112.991749][ T5448] netdevsim netdevsim0 netdevsim1: renamed from eth1
[  113.017492][ T5448] netdevsim netdevsim0 netdevsim2: renamed from eth2
[  113.041174][ T5448] netdevsim netdevsim0 netdevsim3: renamed from eth3
[  113.154398][ T5448] 8021q: adding VLAN 0 to HW filter on device bond0
[  113.169166][ T5448] 8021q: adding VLAN 0 to HW filter on device team0
[  113.177540][ T2771] bridge0: port 1(bridge_slave_0) entered blocking state
[  113.180718][ T2771] bridge0: port 1(bridge_slave_0) entered forwarding state
[  113.198631][ T2771] bridge0: port 2(bridge_slave_1) entered blocking state
[  113.201931][ T2771] bridge0: port 2(bridge_slave_1) entered forwarding state
[  113.373268][ T5448] 8021q: adding VLAN 0 to HW filter on device batadv0
[  113.413044][ T5448] veth0_vlan: entered promiscuous mode
[  113.421970][ T5448] veth1_vlan: entered promiscuous mode
[  113.447766][ T5448] veth0_macvtap: entered promiscuous mode
[  113.456508][ T5448] veth1_macvtap: entered promiscuous mode
[  113.471225][ T5448] batman_adv: batadv0: Interface activated: batadv_slave_0
[  113.482670][ T5448] batman_adv: batadv0: Interface activated: batadv_slave_1
[  113.493595][ T2771] netdevsim netdevsim0 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
[  113.505069][ T2771] netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
[  113.508921][ T2771] netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
[  113.522309][ T2771] netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
[  113.610278][   T46] Bluetooth: hci1: command tx timeout
[  113.615663][ T3065] wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[  113.618967][ T3065] wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50
[  113.699149][  T798] wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[  113.711107][  T798] wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
SYZFAIL: failed to recv rpc
fd=3 want=4 recv=0 n=0 (errno 9: Bad file descriptor)
[  114.442863][   T54] netdevsim netdevsim3 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[  114.532631][   T54] netdevsim netdevsim3 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[  114.581488][   T54] netdevsim netdevsim3 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[  114.641414][   T54] netdevsim netdevsim3 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[  114.839186][   T54] bridge_slave_1: left allmulticast mode
[  114.850926][   T54] bridge_slave_1: left promiscuous mode
[  114.854355][   T54] bridge0: port 2(bridge_slave_1) entered disabled state
[  114.881250][   T54] bridge_slave_0: left allmulticast mode
[  114.883858][   T54] bridge_slave_0: left promiscuous mode
[  114.886705][   T54] bridge0: port 1(bridge_slave_0) entered disabled state
[  115.293575][   T54] bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
[  115.300325][   T54] bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
[  115.309887][   T54] bond0 (unregistering): Released all slaves
[  116.047083][   T54] hsr_slave_0: left promiscuous mode
[  116.060226][   T54] hsr_slave_1: left promiscuous mode
[  116.065846][   T54] batman_adv: batadv0: Interface deactivated: batadv_slave_0
[  116.069298][   T54] batman_adv: batadv0: Removing interface: batadv_slave_0
[  116.084680][   T54] batman_adv: batadv0: Interface deactivated: batadv_slave_1
[  116.088159][   T54] batman_adv: batadv0: Removing interface: batadv_slave_1
[  116.112364][   T54] veth1_macvtap: left promiscuous mode
[  116.115032][   T54] veth0_macvtap: left promiscuous mode
[  116.117616][   T54] veth1_vlan: left promiscuous mode
[  116.122611][   T54] veth0_vlan: left promiscuous mode
[  116.507298][   T54] team0 (unregistering): Port device team_slave_1 removed
[  116.537481][   T54] team0 (unregistering): Port device team_slave_0 removed
[  117.113976][   T54] netdevsim netdevsim0 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[  117.190761][   T54] netdevsim netdevsim0 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[  117.262566][   T54] netdevsim netdevsim0 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[  117.322020][   T54] netdevsim netdevsim0 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[  117.474016][   T54] bridge_slave_1: left allmulticast mode
[  117.476688][   T54] bridge_slave_1: left promiscuous mode
[  117.479097][   T54] bridge0: port 2(bridge_slave_1) entered disabled state
[  117.495996][   T54] bridge_slave_0: left allmulticast mode
[  117.498353][   T54] bridge_slave_0: left promiscuous mode
[  117.507892][   T54] bridge0: port 1(bridge_slave_0) entered disabled state
[  117.753525][   T54] bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
[  117.758959][   T54] bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
[  117.764091][   T54] bond0 (unregistering): Released all slaves
[  118.041937][   T54] hsr_slave_0: left promiscuous mode
[  118.052657][   T54] hsr_slave_1: left promiscuous mode
[  118.059763][   T54] batman_adv: batadv0: Interface deactivated: batadv_slave_0
[  118.062927][   T54] batman_adv: batadv0: Removing interface: batadv_slave_0
[  118.077683][   T54] batman_adv: batadv0: Interface deactivated: batadv_slave_1
[  118.087327][   T54] batman_adv: batadv0: Removing interface: batadv_slave_1
[  118.106384][   T54] veth1_macvtap: left promiscuous mode
[  118.109267][   T54] veth0_macvtap: left promiscuous mode
[  118.127373][   T54] veth1_vlan: left promiscuous mode
[  118.134543][   T54] veth0_vlan: left promiscuous mode
[  118.544069][   T54] team0 (unregistering): Port device team_slave_1 removed
[  118.571533][   T54] 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-build1938936624=/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 d1b870e1003b
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=d1b870e1003b52891d2196c1e2ee42fe905010ba -X github.com/google/syzkaller/prog.gitRevisionDate=20251128-125159"  ./sys/syz-sysgen | grep -q false || go install -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=d1b870e1003b52891d2196c1e2ee42fe905010ba -X github.com/google/syzkaller/prog.gitRevisionDate=20251128-125159"  ./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=d1b870e1003b52891d2196c1e2ee42fe905010ba -X github.com/google/syzkaller/prog.gitRevisionDate=20251128-125159"  -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=\"d1b870e1003b52891d2196c1e2ee42fe905010ba\"
/usr/bin/ld: /tmp/cchOGWWt.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


Error text is too large and was truncated, full error text is at:
https://syzkaller.appspot.com/x/error.txt?x=110920fc580000


Tested on:

commit:         b9275466 Merge tag 'dma-mapping-6.19-2025-12-22' of gi..
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=513255d80ab78f2b
dashboard link: https://syzkaller.appspot.com/bug?extid=9ca2c6e6b098bf5ae60a
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=10706f1a580000

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