Re: [syzbot] [kvm?] INFO: task hung in kvm_gmem_release (2)

Re: [syzbot] [kvm?] INFO: task hung in kvm_gmem_release (2)

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+ab6273c58262b9de56d9@syzkaller.appspotmail.com
Tested-by: syzbot+ab6273c58262b9de56d9@syzkaller.appspotmail.com

Tested on:

commit:         50d05c7c Merge tag 'landlock-7.3-rc3' of git://git.ker..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=118642d1580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5e4e3a0e188a497e
dashboard link: https://syzkaller.appspot.com/bug?extid=ab6273c58262b9de56d9
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: i386
patch:          https://syzkaller.appspot.com/x/patch.diff?x=13d7e925580000

Note: testing is done by a robot and is best-effort only.

Re: [syzbot] [kvm?] INFO: task hung in kvm_gmem_release (2)

[syzbot]

Hello,

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

SYZFAIL: failed to recv rpc

SYZFAIL: failed to recv rpc
fd=3 want=4 recv=0 n=0 (errno 9: Bad file descriptor)
execution of simple program fails: NOTFAIL: arptable checkpoint: getsockopt(ARPT_SO_GET_ENTRIES) failed. table=filter (errno 22: Invalid argument).


Warning: Permanently added '10.128.1.180' (ED25519) to the list of known hosts.
2026/09/15 10:03:47 parsed 1 programs
2026/09/15 10:03:47 serving rpc on tcp://35899
[   92.298308][   T10] cfg80211: failed to load regulatory.db
[   94.705243][ T5628] cgroup: Unknown subsys name 'net'
[   94.819768][ T5628] cgroup: Unknown subsys name 'cpuset'
[   94.823833][ T5628] cgroup: Unknown subsys name 'rlimit'
Setting up swapspace version 1, size = 127995904 bytes
[   96.633598][ T5628] Adding 124996k swap on ./swap-file.  Priority:0 extents:1 across:124996k 
[   99.775137][ T5645] soft_limit_in_bytes is deprecated and will be removed. Writing any value to this file has no effect. Please report your usecase to linux-mm@kvack.org if you depend on this functionality.
[   99.798351][ T5645] ebtables: xtables 32bit compat interface no longer supported in namespaces and will be removed soon.
[   99.815191][ T5645] arp_tables: xtables 32bit compat interface no longer supported in namespaces and will be removed soon.
[  100.401545][ T1175] wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[  100.401572][ T1175] wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50
[  100.456794][   T50] wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[  100.456818][   T50] wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
[  101.850164][ T5670] ip_tables: xtables 32bit compat interface no longer supported in namespaces and will be removed soon.
[  101.850560][ T5670] ip6_tables: xtables 32bit compat interface no longer supported in namespaces and will be removed soon.
[  102.501627][ T5676] bridge0: port 1(bridge_slave_0) entered blocking state
[  102.502376][ T5676] bridge0: port 1(bridge_slave_0) entered disabled state
[  102.502493][ T5676] bridge_slave_0: entered allmulticast mode
[  102.504536][ T5676] bridge_slave_0: entered promiscuous mode
[  102.522188][ T5676] bridge0: port 2(bridge_slave_1) entered blocking state
[  102.522347][ T5676] bridge0: port 2(bridge_slave_1) entered disabled state
[  102.522511][ T5676] bridge_slave_1: entered allmulticast mode
[  102.533089][ T5676] bridge_slave_1: entered promiscuous mode
[  102.590213][ T5676] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
[  102.592992][ T5676] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link
[  102.632923][ T5676] team0: Port device team_slave_0 added
[  102.636138][ T5676] team0: Port device team_slave_1 added
[  102.669819][ T5676] batman_adv: batadv0: Adding interface: batadv_slave_0
[  102.669834][ T5676] 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.
[  102.669858][ T5676] batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active
[  102.672214][ T5676] batman_adv: batadv0: Adding interface: batadv_slave_1
[  102.672229][ T5676] 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.
[  102.672260][ T5676] batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
[  102.791250][ T5676] hsr_slave_0: entered promiscuous mode
[  102.792721][ T5676] hsr_slave_1: entered promiscuous mode
[  102.977390][ T5676] netdevsim netdevsim6 netdevsim0: renamed from eth0
[  102.984696][ T5676] 8021q: adding VLAN 0 to HW filter on device netdevsim0
[  102.996682][ T5676] netdevsim netdevsim6 netdevsim1: renamed from eth1
[  103.011000][ T5676] 8021q: adding VLAN 0 to HW filter on device netdevsim1
[  103.012159][ T5676] netdevsim netdevsim6 netdevsim2: renamed from eth2
[  103.032735][ T5676] 8021q: adding VLAN 0 to HW filter on device netdevsim2
[  103.033682][ T5676] netdevsim netdevsim6 netdevsim3: renamed from eth3
[  103.051624][ T5676] 8021q: adding VLAN 0 to HW filter on device netdevsim3
[  103.089001][ T5676] bridge0: port 2(bridge_slave_1) entered blocking state
[  103.089112][ T5676] bridge0: port 2(bridge_slave_1) entered forwarding state
[  103.089670][ T5676] bridge0: port 1(bridge_slave_0) entered blocking state
[  103.089758][ T5676] bridge0: port 1(bridge_slave_0) entered forwarding state
[  103.183781][ T5676] 8021q: adding VLAN 0 to HW filter on device bond0
[  103.206356][ T1175] bridge0: port 1(bridge_slave_0) entered disabled state
[  103.208344][ T1175] bridge0: port 2(bridge_slave_1) entered disabled state
[  103.236601][ T5676] 8021q: adding VLAN 0 to HW filter on device team0
[  103.245025][ T1037] bridge0: port 1(bridge_slave_0) entered blocking state
[  103.245127][ T1037] bridge0: port 1(bridge_slave_0) entered forwarding state
[  103.275267][ T1175] bridge0: port 2(bridge_slave_1) entered blocking state
[  103.276466][ T1175] bridge0: port 2(bridge_slave_1) entered forwarding state
[  103.682714][ T5676] 8021q: adding VLAN 0 to HW filter on device batadv0
[  103.944689][ T5676] veth0_vlan: entered promiscuous mode
[  103.963472][ T5676] veth1_vlan: entered promiscuous mode
[  104.009708][ T5676] veth0_macvtap: entered promiscuous mode
[  104.016196][ T5676] veth1_macvtap: entered promiscuous mode
[  104.051538][ T5676] batman_adv: batadv0: Interface activated: batadv_slave_0
[  104.073599][ T5676] batman_adv: batadv0: Interface activated: batadv_slave_1
[  104.163515][ T1175] netdevsim netdevsim6 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
[  104.163925][ T1175] netdevsim netdevsim6 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
[  104.163961][ T1175] netdevsim netdevsim6 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
[  104.164004][ T1175] netdevsim netdevsim6 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
[  104.338037][   T13] netdevsim netdevsim6 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[  104.481043][   T13] netdevsim netdevsim6 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[  104.541977][   T13] netdevsim netdevsim6 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[  104.620294][   T13] netdevsim netdevsim6 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[  105.627300][   T52] Bluetooth: hci0: unexpected cc 0x0c03 length: 249 > 1
[  105.627982][   T52] Bluetooth: hci0: unexpected cc 0x1003 length: 249 > 9
[  105.628534][   T52] Bluetooth: hci0: unexpected cc 0x1001 length: 249 > 9
[  105.629728][   T52] Bluetooth: hci0: unexpected cc 0x0c23 length: 249 > 4
[  105.630376][   T52] Bluetooth: hci0: unexpected cc 0x0c38 length: 249 > 2
[  105.917265][   T13] bridge_slave_1: left allmulticast mode
[  105.917315][   T13] bridge_slave_1: left promiscuous mode
[  105.918225][   T13] bridge0: port 2(bridge_slave_1) entered disabled state
[  105.951678][   T13] bridge_slave_0: left allmulticast mode
[  105.951709][   T13] bridge_slave_0: left promiscuous mode
[  105.953700][   T13] bridge0: port 1(bridge_slave_0) entered disabled state
[  106.194217][   T13] bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
[  106.218127][   T13] bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
[  106.219936][   T13] bond0 (unregistering): Released all slaves
[  106.358701][   T13] hsr_slave_0: left promiscuous mode
[  106.359698][   T13] hsr_slave_1: left promiscuous mode
[  106.361694][   T13] batman_adv: batadv0: Interface deactivated: batadv_slave_0
[  106.361805][   T13] batman_adv: batadv0: Removing interface: batadv_slave_0
[  106.364165][   T13] batman_adv: batadv0: Interface deactivated: batadv_slave_1
[  106.364186][   T13] batman_adv: batadv0: Removing interface: batadv_slave_1
[  106.428453][   T13] veth1_macvtap: left promiscuous mode
[  106.428514][   T13] veth0_macvtap: left promiscuous mode
[  106.428623][   T13] veth1_vlan: left promiscuous mode
[  106.428718][   T13] veth0_vlan: left promiscuous mode
[  106.729824][   T13] team0 (unregistering): Port device team_slave_1 removed
[  106.749999][   T13] team0 (unregistering): Port device team_slave_0 removed
[  106.863908][ T5281] 8021q: adding VLAN 0 to HW filter on device eth1
SYZFAIL: failed to recv rpc
fd=3 want=4 recv=0 n=0 (errno 9: Bad file descriptor)
execution of simple program fails: NOTFAIL: arptable checkpoint: getsockopt(ARPT_SO_GET_ENTRIES) failed. table=filter (errno 22: Invalid argument).
[  107.874113][ T5281] 8021q: adding VLAN 0 to HW filter on device eth2
[  108.744031][ T5281] 8021q: adding VLAN 0 to HW filter on device eth3
[  109.188685][ T5281] 8021q: adding VLAN 0 to HW filter on device eth4


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-build40483423=/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='go1.26.0'
GOWORK=''
PKG_CONFIG='pkg-config'

git status (err=<nil>)
HEAD detached at 1fe56c0af80
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=1fe56c0af80df10ab9f07819d9fa709dc9971ae1 -X github.com/google/syzkaller/prog.gitRevisionDate=20260910-094642"  ./sys/syz-sysgen | grep -q false || go install -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=1fe56c0af80df10ab9f07819d9fa709dc9971ae1 -X github.com/google/syzkaller/prog.gitRevisionDate=20260910-094642"  ./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=1fe56c0af80df10ab9f07819d9fa709dc9971ae1 -X github.com/google/syzkaller/prog.gitRevisionDate=20260910-094642"  -o ./bin/linux_amd64/syz-execprog github.com/google/syzkaller/tools/syz-execprog
mkdir -p ./bin/linux_386
x86_64-linux-gnu-g++ -o ./bin/linux_386/syz-executor executor/executor.cc \
	-m32 -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_386=1 \
	-DHOSTGOOS_linux=1 -DGIT_REVISION=\"1fe56c0af80df10ab9f07819d9fa709dc9971ae1\"
/usr/bin/ld: /tmp/cc3yk8t3.o: in function `Connection::Connect(char const*, char const*)':
executor.cc:(.text._ZN10Connection7ConnectEPKcS1_[_ZN10Connection7ConnectEPKcS1_]+0x145): 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
[INFO] Unsupported architecture '386', skipping check.



Tested on:

commit:         58785836 Merge tag 'nfsd-7.3-1' of git://git.kernel.or..
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=5e4e3a0e188a497e
dashboard link: https://syzkaller.appspot.com/bug?extid=ab6273c58262b9de56d9
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: i386
patch:          https://syzkaller.appspot.com/x/patch.diff?x=155f2115580000

Re: [syzbot] [kvm?] INFO: task hung in kvm_gmem_release (2)

[Sean Christopherson]

On Fri, Sep 11, 2026, syzbot wrote:
> syzbot found the following issue on:
> 
> HEAD commit:    50d05c7c76c9 Merge tag 'landlock-7.3-rc3' of git://git.ker..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=13db5ef9580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=5e4e3a0e188a497e
> dashboard link: https://syzkaller.appspot.com/bug?extid=ab6273c58262b9de56d9
> compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
> userspace arch: i386
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=143121f9580000

The reproducer is "only" setting memory attributes on a 16MiB range.  I was
expecting a much, much larger range.  I suspect this one may be due to a problem
with the underlying GCE host?  Though it did spit out a reproducer...

> CPU: 1 UID: 0 PID: 6083 Comm: syz.4.24 Not tainted syzkaller #0 PREEMPT(full) 
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
> RIP: 0010:__this_cpu_preempt_check+0x0/0x20 lib/smp_processor_id.c:63
> Code: f5 48 8b 74 24 20 48 c7 c7 00 9b 6d 8c e8 88 ac 42 f5 e8 23 ab 4d f5 eb ae 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 48 89 fe 48 c7 c7 80 9a 6d 8c e9 0d ff ff ff cc cc cc
> RSP: 0018:ffffc90003d27460 EFLAGS: 00000046
> RAX: 0000000000000001 RBX: 0000000000000001 RCX: 8000000000000001
> RDX: 0000000000000000 RSI: ffff88807ea4a3d0 RDI: ffffffff8e6fe7fc
> RBP: 00000000ffffffff R08: ffffc90003d2755f R09: 0000000000000000
> R10: ffffc90003d27548 R11: fffff520007a4eac R12: 0000000000000246
> R13: ffff8880314c5dc0 R14: ffff88807ea4a3d0 R15: 0000000000000001
> FS:  0000000000000000(0000) GS:ffff888124dd2000(0063) knlGS:00000000f6834b40
> CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
> CR2: 00000000f71e8c10 CR3: 0000000073d5a000 CR4: 00000000003526f0
> Call Trace:
>  <TASK>
>  lockdep_recursion_finish kernel/locking/lockdep.c:470 [inline]
>  lock_is_held_type+0xdf/0x150 kernel/locking/lockdep.c:6017
>  lock_is_held include/linux/lockdep.h:249 [inline]
>  xa_entry include/linux/xarray.h:1227 [inline]
>  xas_descend lib/xarray.c:208 [inline]
>  xas_load+0x198/0x5a0 lib/xarray.c:246
>  __xa_cmpxchg_raw lib/xarray.c:1783 [inline]
>  __xa_cmpxchg+0xc3/0x1f0 lib/xarray.c:1769
>  xa_cmpxchg include/linux/xarray.h:699 [inline]
>  xa_reserve include/linux/xarray.h:1088 [inline]
>  kvm_vm_set_mem_attributes virt/kvm/kvm_main.c:2577 [inline]
>  kvm_vm_ioctl_set_mem_attributes+0x429/0x1600 virt/kvm/kvm_main.c:2625
>  kvm_vm_ioctl+0xb33/0xd30 virt/kvm/kvm_main.c:5356
>  kvm_vm_compat_ioctl+0x2b1/0x3a0 virt/kvm/kvm_main.c:5480
>  __do_compat_sys_ioctl fs/ioctl.c:695 [inline]
>  __se_compat_sys_ioctl fs/ioctl.c:638 [inline]
>  __ia32_compat_sys_ioctl+0x5ea/0x950 fs/ioctl.c:638
>  do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:79 [inline]
>  __do_fast_syscall_32+0x27a/0x6a0 arch/x86/entry/syscall_32.c:291
>  do_fast_syscall_32+0x33/0x70 arch/x86/entry/syscall_32.c:316
>  entry_SYSENTER_compat_after_hwframe+0x84/0x8e
> RIP: 0023:0xf705f0ec
> Code: 90 85 d2 74 0a 89 ce 81 e6 ff 0f 00 00 89 32 85 c0 74 05 c1 e9 0c 89 08 31 c0 5e 5d c3 90 0f 1f 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 58 b8
> RSP: 002b:00000000f683450c EFLAGS: 00000206 ORIG_RAX: 0000000000000036
> RAX: ffffffffffffffda RBX: 0000000000000007 RCX: 000000004020aed2
> RDX: 0000000080000200 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
>  </TASK>

[syzbot] [kvm?] INFO: task hung in kvm_gmem_release (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    50d05c7c76c9 Merge tag 'landlock-7.3-rc3' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13db5ef9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5e4e3a0e188a497e
dashboard link: https://syzkaller.appspot.com/bug?extid=ab6273c58262b9de56d9
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: i386
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=143121f9580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/daf497619736/disk-50d05c7c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/748fbd82f647/vmlinux-50d05c7c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e61c59099d07/bzImage-50d05c7c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ab6273c58262b9de56d9@syzkaller.appspotmail.com

INFO: task syz.0.17:5886 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.17        state:D stack:25512 pid:5886  tgid:5886  ppid:5771   task_flags:0x400040 flags:0x08080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5526 [inline]
 __schedule+0x17db/0x58f0 kernel/sched/core.c:7276
 __schedule_loop kernel/sched/core.c:7353 [inline]
 schedule+0x164/0x2b0 kernel/sched/core.c:7368
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7425
 __mutex_lock_common kernel/locking/mutex.c:726 [inline]
 __mutex_lock+0x7c1/0x1550 kernel/locking/mutex.c:821
 kvm_gmem_release+0xdf/0x3e0 virt/kvm/guest_memfd.c:310
 __fput+0x418/0xa50 fs/file_table.c:512
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:70 [inline]
 exit_to_user_mode_loop+0x204/0x770 kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:336 [inline]
 __do_fast_syscall_32+0x437/0x6a0 arch/x86/entry/syscall_32.c:294
 do_fast_syscall_32+0x33/0x70 arch/x86/entry/syscall_32.c:316
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf7f660ec
RSP: 002b:00000000ff830cbc EFLAGS: 00000206 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 000000000000001e
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>

Showing all locks held in the system:
locks held by khungtaskd/32: 1, last CPU#0:
 #0: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6871
locks held by getty/5374: 2, on CPU#1:
 #0: ffff88803555b0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000322b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211
locks held by syz.0.17/5886: 1, on CPU#1:
 #0: ffff8880597c00a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_gmem_release+0xdf/0x3e0 virt/kvm/guest_memfd.c:310
locks held by syz.0.17/5889: 1, last CPU#1:
 #0: ffff8880597c00a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_set_mem_attributes virt/kvm/kvm_main.c:2566 [inline]
 #0: ffff8880597c00a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_ioctl_set_mem_attributes+0x33c/0x1600 virt/kvm/kvm_main.c:2625
locks held by syz.1.20/5950: 1, on CPU#1:
 #0: ffff88807ea780a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_gmem_release+0xdf/0x3e0 virt/kvm/guest_memfd.c:310
locks held by syz.1.20/5952: 1, last CPU#1:
 #0: ffff88807ea780a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_set_mem_attributes virt/kvm/kvm_main.c:2566 [inline]
 #0: ffff88807ea780a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_ioctl_set_mem_attributes+0x33c/0x1600 virt/kvm/kvm_main.c:2625
locks held by syz.2.21/5991: 1, on CPU#0:
 #0: ffff8880291340a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_gmem_release+0xdf/0x3e0 virt/kvm/guest_memfd.c:310
locks held by syz.2.21/5993: 1, last CPU#0:
 #0: ffff8880291340a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_set_mem_attributes virt/kvm/kvm_main.c:2566 [inline]
 #0: ffff8880291340a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_ioctl_set_mem_attributes+0x33c/0x1600 virt/kvm/kvm_main.c:2625
locks held by syz.3.23/6034: 1, on CPU#1:
 #0: ffff88807b7ac0a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_gmem_release+0xdf/0x3e0 virt/kvm/guest_memfd.c:310
locks held by syz.3.23/6036: 1, last CPU#0:
 #0: ffff88807b7ac0a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_set_mem_attributes virt/kvm/kvm_main.c:2566 [inline]
 #0: ffff88807b7ac0a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_ioctl_set_mem_attributes+0x33c/0x1600 virt/kvm/kvm_main.c:2625
locks held by syz.4.24/6081: 1, on CPU#0:
 #0: ffff88807ea480a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_gmem_release+0xdf/0x3e0 virt/kvm/guest_memfd.c:310
locks held by syz.4.24/6083: 2, last CPU#1:
 #0: ffff88807ea480a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_set_mem_attributes virt/kvm/kvm_main.c:2566 [inline]
 #0: ffff88807ea480a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_ioctl_set_mem_attributes+0x33c/0x1600 virt/kvm/kvm_main.c:2625
 #1: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: ieee80211_rx_napi+0xd1/0x3d0 net/mac80211/rx.c:5742
locks held by syz.5.27/6142: 1, on CPU#1:
 #0: ffff888072ba00a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_gmem_release+0xdf/0x3e0 virt/kvm/guest_memfd.c:310
locks held by syz.5.27/6144: 1, last CPU#0:
 #0: ffff888072ba00a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_set_mem_attributes virt/kvm/kvm_main.c:2566 [inline]
 #0: ffff888072ba00a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_ioctl_set_mem_attributes+0x33c/0x1600 virt/kvm/kvm_main.c:2625
locks held by syz.6.28/6190: 1, on CPU#1:
 #0: ffff88807090c0a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_gmem_release+0xdf/0x3e0 virt/kvm/guest_memfd.c:310
locks held by syz.6.28/6192: 1, last CPU#0:
 #0: ffff88807090c0a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_set_mem_attributes virt/kvm/kvm_main.c:2566 [inline]
 #0: ffff88807090c0a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_ioctl_set_mem_attributes+0x33c/0x1600 virt/kvm/kvm_main.c:2625
locks held by syz.7.29/6246: 1, on CPU#1:
 #0: ffff888032ad40a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_gmem_release+0xdf/0x3e0 virt/kvm/guest_memfd.c:310
locks held by syz.7.29/6248: 1, last CPU#1:
 #0: ffff888032ad40a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_set_mem_attributes virt/kvm/kvm_main.c:2566 [inline]
 #0: ffff888032ad40a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_ioctl_set_mem_attributes+0x33c/0x1600 virt/kvm/kvm_main.c:2625

=============================================

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 32 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:123
 nmi_trigger_cpumask_backtrace+0x17d/0x390 lib/nmi_backtrace.c:66
 trigger_all_cpu_backtrace include/linux/nmi.h:164 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
 watchdog+0xfd7/0x1030 kernel/hung_task.c:561
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6083 Comm: syz.4.24 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__this_cpu_preempt_check+0x0/0x20 lib/smp_processor_id.c:63
Code: f5 48 8b 74 24 20 48 c7 c7 00 9b 6d 8c e8 88 ac 42 f5 e8 23 ab 4d f5 eb ae 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 48 89 fe 48 c7 c7 80 9a 6d 8c e9 0d ff ff ff cc cc cc
RSP: 0018:ffffc90003d27460 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 0000000000000001 RCX: 8000000000000001
RDX: 0000000000000000 RSI: ffff88807ea4a3d0 RDI: ffffffff8e6fe7fc
RBP: 00000000ffffffff R08: ffffc90003d2755f R09: 0000000000000000
R10: ffffc90003d27548 R11: fffff520007a4eac R12: 0000000000000246
R13: ffff8880314c5dc0 R14: ffff88807ea4a3d0 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff888124dd2000(0063) knlGS:00000000f6834b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f71e8c10 CR3: 0000000073d5a000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 lockdep_recursion_finish kernel/locking/lockdep.c:470 [inline]
 lock_is_held_type+0xdf/0x150 kernel/locking/lockdep.c:6017
 lock_is_held include/linux/lockdep.h:249 [inline]
 xa_entry include/linux/xarray.h:1227 [inline]
 xas_descend lib/xarray.c:208 [inline]
 xas_load+0x198/0x5a0 lib/xarray.c:246
 __xa_cmpxchg_raw lib/xarray.c:1783 [inline]
 __xa_cmpxchg+0xc3/0x1f0 lib/xarray.c:1769
 xa_cmpxchg include/linux/xarray.h:699 [inline]
 xa_reserve include/linux/xarray.h:1088 [inline]
 kvm_vm_set_mem_attributes virt/kvm/kvm_main.c:2577 [inline]
 kvm_vm_ioctl_set_mem_attributes+0x429/0x1600 virt/kvm/kvm_main.c:2625
 kvm_vm_ioctl+0xb33/0xd30 virt/kvm/kvm_main.c:5356
 kvm_vm_compat_ioctl+0x2b1/0x3a0 virt/kvm/kvm_main.c:5480
 __do_compat_sys_ioctl fs/ioctl.c:695 [inline]
 __se_compat_sys_ioctl fs/ioctl.c:638 [inline]
 __ia32_compat_sys_ioctl+0x5ea/0x950 fs/ioctl.c:638
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:79 [inline]
 __do_fast_syscall_32+0x27a/0x6a0 arch/x86/entry/syscall_32.c:291
 do_fast_syscall_32+0x33/0x70 arch/x86/entry/syscall_32.c:316
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf705f0ec
Code: 90 85 d2 74 0a 89 ce 81 e6 ff 0f 00 00 89 32 85 c0 74 05 c1 e9 0c 89 08 31 c0 5e 5d c3 90 0f 1f 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 58 b8
RSP: 002b:00000000f683450c EFLAGS: 00000206 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000007 RCX: 000000004020aed2
RDX: 0000000080000200 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>


---
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