[syzbot] [fs?] [mm?] WARNING in sched_mm_cid_fork

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7d31f578f323 Add linux-next specific files for 20251128
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=165b14b4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6336d8e94a7c517d
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
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=104a30c2580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6b49d8ad90de/disk-7d31f578.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/dbe2d4988ca7/vmlinux-7d31f578.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fc0448ab2411/bzImage-7d31f578.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9ca2c6...@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: kernel/sched/core.c:10573 at sched_mm_cid_fork+0x66/0xc30 kernel/sched/core.c:10573, CPU#0: kworker/u8:4/6077
Modules linked in:
CPU: 0 UID: 0 PID: 6077 Comm: kworker/u8:4 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:sched_mm_cid_fork+0x66/0xc30 kernel/sched/core.c:10573
Code: 4c 8b 3b 4d 85 ff 74 21 49 8d 9d d4 15 00 00 48 89 d8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 13 0a 00 00 31 c0 3b 03 70 04 90 <0f> 0b 90 49 8d 9f 00 01 00 00 49 8d bf c0 01 00 00 48 89 7c 24 20
RSP: 0018:ffffc90003167bd8 EFLAGS: 00010246
RAX: 1ffff1100584e853 RBX: ffff88802c274298 RCX: ffff88802c273d00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88802c273d00
RBP: ffffc90003167d68 R08: ffffffff8e093e83 R09: 1ffffffff1c127d0
R10: dffffc0000000000 R11: fffffbfff1c127d1 R12: ffff88802c273d00
R13: ffff88802c273d00 R14: dffffc0000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888125e4f000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcc18973e9c CR3: 000000003470a000 CR4: 00000000003526f0
Call Trace:
<TASK>
bprm_execve+0xd88/0x1400 fs/exec.c:1776
kernel_execve+0x8f0/0x9f0 fs/exec.c:1919
call_usermodehelper_exec_async+0x210/0x360 kernel/umh.c:109
ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
</TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: d358e5254674 Merge tag 'for-6.19/dm-changes' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11c0d1c2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=de48dccdf203ea90

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

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=144621b4580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=124621b4580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-d358e525.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3fa1d04c1a85/vmlinux-d358e525.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a9b253146e36/bzImage-d358e525.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/4a5df3575982/mount_1.gz
fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=11119592580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9ca2c6...@syzkaller.appspotmail.com

------------[ cut here ]------------

WARNING: kernel/sched/core.c:10569 at sched_mm_cid_fork+0x66/0xc30 kernel/sched/core.c:10569, CPU#0: kworker/u4:4/5674
Modules linked in:
CPU: 0 UID: 0 PID: 5674 Comm: kworker/u4:4 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:sched_mm_cid_fork+0x66/0xc30 kernel/sched/core.c:10569

Code: 4c 8b 3b 4d 85 ff 74 21 49 8d 9d d4 15 00 00 48 89 d8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 13 0a 00 00 31 c0 3b 03 70 04 90 <0f> 0b 90 49 8d 9f 00 01 00 00 49 8d bf c0 01 00 00 48 89 7c 24 20

RSP: 0000:ffffc900036cfbd8 EFLAGS: 00010246
RAX: 1ffff110067b79e3 RBX: ffff888033dbcf18 RCX: ffff888033dbc980
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888033dbc980
RBP: ffffc900036cfd68 R08: ffffffff8e295e83 R09: 1ffffffff1c52bd0
R10: dffffc0000000000 R11: fffffbfff1c52bd1 R12: ffff888033dbc980
R13: ffff888033dbc980 R14: dffffc0000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88808d22f000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007f6ad913e000 CR3: 0000000041a50000 CR4: 0000000000352ef0

Call Trace:
<TASK>
bprm_execve+0xd88/0x1400 fs/exec.c:1776
kernel_execve+0x8f0/0x9f0 fs/exec.c:1919
call_usermodehelper_exec_async+0x210/0x360 kernel/umh.c:109
ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
</TASK>


---

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-...@vger.kernel.org, syzkall...@googlegroups.com.

***

Subject: [PATCH] exec: do not call sched_mm_cid_after_execve() on exec fail
Author: wangjin...@gmail.com

sched_mm_cid_after_execve() is called from the failure path
of bprm_execve(). At that point exec has not completed successfully,
so updating the mm CID state is incorrect and can trigger a panic,
as reported by syzbot.

Remove the call from the exec failure path.

#syz test
Reported-by: syzbot+9ca2c6...@syzkaller.appspotmail.com
Signed-off-by: Jinchao Wang <wangjin...@gmail.com>
---
fs/exec.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/fs/exec.c b/fs/exec.c
index 9d5ebc9d15b0..9044a75d26ab 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1773,7 +1773,6 @@ static int bprm_execve(struct linux_binprm *bprm)
if (bprm->point_of_no_return && !fatal_signal_pending(current))
force_fatal_sig(SIGSEGV);

- sched_mm_cid_after_execve(current);
rseq_force_update();
current->in_execve = 0;

--
2.43.0

[syzbot]

Hello,

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

failed to copy binary to VM: failed to run ["scp" "-P" "14194" "-F" "/dev/null" "-o" "UserKnownHostsFile=/dev/null" "-o" "IdentitiesOnly=yes" "-o" "BatchMode=yes" "-o" "StrictHostKeyChecking=no" "-o" "ConnectTimeout=10" "/tmp/syz-executor485896482" "root@localhost:/syz-executor485896482"]: exit status 255



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-build4211968964=/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/ccmP3lG1.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: ea1013c1 Merge tag 'bpf-fixes' of git://git.kernel.org..
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=10ae977c580000

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-...@vger.kernel.org, syzkall...@googlegroups.com.

***

Subject: [PATCH] exec: do not call sched_mm_cid_after_execve() on exec fail
Author: wangjin...@gmail.com

sched_mm_cid_after_execve() is called from the failure path
of bprm_execve(). At that point exec has not completed successfully,
so updating the mm CID state is incorrect and can trigger a panic,
as reported by syzbot.

Remove the call from the exec failure path.

#syz test

Cc: sta...@vger.kernel.org

[syzbot]

Hello,

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

failed to copy binary to VM: failed to run ["scp" "-P" "1814" "-F" "/dev/null" "-o" "UserKnownHostsFile=/dev/null" "-o" "IdentitiesOnly=yes" "-o" "BatchMode=yes" "-o" "StrictHostKeyChecking=no" "-o" "ConnectTimeout=10" "/tmp/syz-executor2977063156" "root@localhost:/syz-executor2977063156"]: exit status 255

GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build1046867334=/tmp/go-build -gno-record-gcc-switches'

/usr/bin/ld: /tmp/cc3BBp1I.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: ea1013c1 Merge tag 'bpf-fixes' of git://git.kernel.org..
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=1439631a580000

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-...@vger.kernel.org, syzkall...@googlegroups.com.

***

Subject: [PATCH] exec: do not call sched_mm_cid_after_execve() on exec fail
Author: wangjin...@gmail.com

sched_mm_cid_after_execve() is called from the failure path
of bprm_execve(). At that point exec has not completed successfully,
so updating the mm CID state is incorrect and can trigger a panic,
as reported by syzbot.

Remove the call from the exec failure path.

#syz test

[syzbot]

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

GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build1938936624=/tmp/go-build -gno-record-gcc-switches'

/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

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-...@vger.kernel.org, syzkall...@googlegroups.com.

***

Subject: call for test on upstream
Author: wangjin...@gmail.com

#syz test

only used to check the process of this issue.

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in sched_mm_cid_fork

------------[ cut here ]------------
WARNING: kernel/sched/core.c:10569 at sched_mm_cid_fork+0x66/0xc30 kernel/sched/core.c:10569, CPU#0: kworker/u4:21/5944
Modules linked in:
CPU: 0 UID: 0 PID: 5944 Comm: kworker/u4:21 Not tainted syzkaller #0 PREEMPT(full)

Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:sched_mm_cid_fork+0x66/0xc30 kernel/sched/core.c:10569
Code: 4c 8b 3b 4d 85 ff 74 21 49 8d 9d d4 15 00 00 48 89 d8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 13 0a 00 00 31 c0 3b 03 70 04 90 <0f> 0b 90 49 8d 9f 00 01 00 00 49 8d bf c0 01 00 00 48 89 7c 24 20

RSP: 0018:ffffc900037d7c18 EFLAGS: 00010246
RAX: 1ffff110069940b3 RBX: ffff888034ca0598 RCX: ffff888034ca0000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888034ca0000
RBP: ffffc900037d7da8 R08: ffffffff8e095e83 R09: 1ffffffff1c12bd0
R10: dffffc0000000000 R11: fffffbfff1c12bd1 R12: ffff888034ca0000
R13: ffff888034ca0000 R14: dffffc0000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88808d416000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007f6acae1a000 CR3: 0000000040cc0000 CR4: 0000000000352ef0

Call Trace:
<TASK>
bprm_execve+0xd88/0x1400 fs/exec.c:1776
kernel_execve+0x8f0/0x9f0 fs/exec.c:1919
call_usermodehelper_exec_async+0x210/0x360 kernel/umh.c:109

ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
</TASK>

Tested on:

commit: b9275466 Merge tag 'dma-mapping-6.19-2025-12-22' of gi..
git tree: upstream

console output: https://syzkaller.appspot.com/x/log.txt?x=12be2022580000

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

Note: no patches were applied.