Re: [syzbot] [kernel?] INFO: task hung in copy_ipcs

[syzbot <syzbot+97a62389c5611b0477f3@syzkaller.appspotmail.com>]

Hello,

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

T1] pci 0000:00:00.0: Limiting direct PCI/PCI transfers
[    7.637106][    T1] PCI: CLS 0 bytes, default 64
[    7.646153][    T1] PCI-DMA: Using software bounce buffering for IO (SWIOTLB)
[    7.658179][    T1] software IO TLB: mapped [mem 0x00000000b4600000-0x00000000b8600000] (64MB)
[    7.680883][    T1] ACPI: bus type thunderbolt registered
[    7.710079][    T1] RAPL PMU: API unit is 2^-32 Joules, 0 fixed counters, 10737418240 ms ovfl timer
[    7.731180][   T69] kworker/u8:1 (69) used greatest stack depth: 27400 bytes left
[    7.795581][    T1] kvm_amd: CPU 1 isn't AMD or Hygon
[    7.802181][    T1] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x1fb63109b96, max_idle_ns: 440795265316 ns
[    7.816978][    T1] clocksource: Switched to clocksource tsc
[    7.842238][   T76] kworker/u8:5 (76) used greatest stack depth: 26368 bytes left
[    7.905527][    T1] Initialise system trusted keyrings
[    7.911207][   T94] kworker/u8:1 (94) used greatest stack depth: 26280 bytes left
[    7.912731][    T1] workingset: timestamp_bits=40 (anon: 35) max_order=21 bucket_order=0 (anon: 0)
[    7.958147][    T1] DLM installed
[    7.971232][    T1] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[    7.996134][    T1] NFS: Registering the id_resolver key type
[    7.999551][    T1] Key type id_resolver registered
[    7.999577][    T1] Key type id_legacy registered
[    8.000110][    T1] nfs4filelayout_init: NFSv4 File Layout Driver Registering...
[    8.025411][    T1] nfs4flexfilelayout_init: NFSv4 Flexfile Layout Driver Registering...
[    8.040786][    T1] smbdirect: subsystem loading...
[    8.060542][    T1] smbdirect: subsystem loaded
[    8.097258][    T1] Key type cifs.spnego registered
[    8.104029][    T1] Key type cifs.idmap registered
[    8.114058][    T1] ntfs3: Enabled Linux POSIX ACLs support
[    8.114071][    T1] ntfs3: Read-only LZX/Xpress compression included
[    8.114489][    T1] jffs2: version 2.2. (NAND) (SUMMARY)  © 2001-2006 Red Hat, Inc.
[    8.129308][    T1] romfs: ROMFS MTD (C) 2007 Red Hat, Inc.
[    8.130705][    T1] QNX4 filesystem 0.2.3 registered.
[    8.131311][    T1] qnx6: QNX6 filesystem 1.0.0 registered.
[    8.146567][    T1] fuse: init (API version 7.45)
[    8.176378][    T1] orangefs_debugfs_init: called with debug mask: :none: :0:
[    8.179625][    T1] orangefs_init: module version upstream loaded
[    8.185398][    T1] JFS: nTxBlock = 8192, nTxLock = 65536
[    8.219377][    T1] SGI XFS with ACLs, security attributes, realtime, scrub, repair, quota, no debug enabled
[    8.247109][    T1] 9p: Installing v9fs 9p2000 file system support
[    8.257306][    T1] NILFS version 2 loaded
[    8.262152][    T1] befs: version: 0.9.3
[    8.273399][    T1] ocfs2: Registered cluster interface o2cb
[    8.283325][    T1] ocfs2: Registered cluster interface user
[    8.293498][    T1] OCFS2 User DLM kernel interface loaded
[    8.343480][    T1] gfs2: GFS2 installed
[    8.373249][    T1] ceph: loaded (mds proto 32)
[    8.398132][    T1] NET: Registered PF_ALG protocol family
[    8.405612][    T1] async_tx: api initialized (async)
[    8.412077][    T1] Key type asymmetric registered
[    8.418707][    T1] Asymmetric key parser 'x509' registered
[    8.425329][    T1] Asymmetric key parser 'pkcs8' registered
[    8.431759][    T1] Key type pkcs7_test registered
[    8.438792][    T1] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 239)
[    8.465902][    T1] io scheduler mq-deadline registered
[    8.474416][    T1] io scheduler kyber registered
[    8.483105][    T1] io scheduler bfq registered
[    8.490544][    T1] raid6: skipped pq benchmark and selected avx2x4
[    8.527365][    T1] input: Power Button as /devices/platform/LNXPWRBN:00/input/input0
[    8.545144][    T1] ACPI: button: Power Button [PWRF]
[    8.549019][    T1] input: Sleep Button as /devices/platform/LNXSLPBN:00/input/input1
[    8.571305][    T1] ACPI: button: Sleep Button [SLPF]
[    8.614419][    T1] ioatdma: Intel(R) QuickData Technology Driver 5.00
[    8.687153][   T10] ACPI: \_SB_.LNKC: Enabled at IRQ 11
[    8.690470][   T10] virtio-pci 0000:00:03.0: virtio_pci: leaving for legacy driver
[    8.777077][   T10] ACPI: \_SB_.LNKD: Enabled at IRQ 10
[    8.777854][   T10] virtio-pci 0000:00:04.0: virtio_pci: leaving for legacy driver
[    8.873818][   T10] ACPI: \_SB_.LNKB: Enabled at IRQ 10
[    8.875911][   T10] virtio-pci 0000:00:06.0: virtio_pci: leaving for legacy driver
[    8.939435][   T10] virtio-pci 0000:00:07.0: virtio_pci: leaving for legacy driver
[   10.196948][    T1] N_HDLC line discipline registered with maxframe=4096
[   10.199967][    T1] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
[   10.232749][    T1] 00:02: ttyS0 I/O:0x3f8 (irq = 4, base_baud = 115200) is a 16550A
[   10.270603][    T1] 00:03: ttyS1 I/O:0x2f8 (irq = 3, base_baud = 115200) is a 16550A
[   10.306472][    T1] 00:04: ttyS2 I/O:0x3e8 (irq = 6, base_baud = 115200) is a 16550A
[   10.347681][    T1] 00:05: ttyS3 I/O:0x2e8 (irq = 7, base_baud = 115200) is a 16550A
[   10.413400][    T1] Non-volatile memory driver v1.3
[   10.488230][    T1] usbcore: registered new interface driver xillyusb
[   10.507411][    T1] ACPI: bus type drm_connector registered
[   10.527904][    T1] [drm] Initialized vgem 1.0.0 for vgem on minor 0
[   10.543037][    T1] ------------[ cut here ]------------
[   10.543071][    T1] [PLANE:35:plane-0] pixel format with alpha exposed but blend mode not setup
[   10.543089][    T1] WARNING: drivers/gpu/drm/drm_mode_config.c:873 at drm_mode_config_validate+0x1c6d/0x1e60, CPU#1: swapper/0/1
[   10.577534][    T1] Modules linked in:
[   10.581844][    T1] CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
[   10.592162][    T1] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
[   10.603955][    T1] RIP: 0010:drm_mode_config_validate+0x1cae/0x1e60
[   10.611147][    T1] Code: 0f 85 ae 00 00 00 4d 8d 77 10 8b 6d 00 4c 89 f0 48 c1 e8 03 80 3c 18 00 74 08 4c 89 f7 e8 9a 52 ab fc 49 8b 16 4c 89 ef 89 ee <67> 48 0f b9 3a eb 05 e8 b6 a6 3e fc 49 bd 00 00 00 00 00 fc ff df
[   10.634269][    T1] RSP: 0000:ffffc90000067810 EFLAGS: 00010246
[   10.640963][    T1] RAX: 1ffff11004b7e608 RBX: dffffc0000000000 RCX: ffff88801c6fddc0
[   10.649850][    T1] RDX: ffff88802664ba00 RSI: 0000000000000023 RDI: ffffffff8fdd4690
[   10.658822][    T1] RBP: 0000000000000023 R08: 0000000000000000 R09: 0000000000000000
[   10.667748][    T1] R10: dffffc0000000000 R11: fffffbfff1fa3f90 R12: dffffc0000000000
[   10.676297][    T1] R13: ffffffff8fdd4690 R14: ffff888025bf3040 R15: ffff888025bf3030
[   10.685045][    T1] FS:  0000000000000000(0000) GS:ffff888125abc000(0000) knlGS:0000000000000000
[   10.695218][    T1] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   10.702591][    T1] CR2: 0000000000000000 CR3: 000000000e1b0000 CR4: 00000000003526f0
[   10.711880][    T1] Call Trace:
[   10.715381][    T1]  <TASK>
[   10.719146][    T1]  ? debugfs_create_file_full+0x3f/0x60
[   10.726076][    T1]  drm_dev_register+0x7f/0xd80
[   10.732072][    T1]  vkms_create+0x40d/0x4f0
[   10.737112][    T1]  ? __pfx_vkms_init+0x10/0x10
[   10.742491][    T1]  vkms_init+0x57/0x80
[   10.746735][    T1]  do_one_initcall+0x250/0x870
[   10.753297][    T1]  ? __pfx_vkms_init+0x10/0x10
[   10.758270][    T1]  ? __pfx_do_one_initcall+0x10/0x10
[   10.766504][    T1]  ? __pfx___schedule+0x10/0x10
[   10.777367][    T1]  ? irqentry_exit+0x218/0x910
[   10.783551][    T1]  ? lockdep_hardirqs_on+0x7a/0x110
[   10.789790][    T1]  ? irqentry_exit+0x218/0x910
[   10.795080][    T1]  ? trace_irq_disable+0x3b/0x140
[   10.801176][    T1]  ? strlen+0x2e/0x70
[   10.805771][    T1]  ? next_arg+0x4a0/0x5e0
[   10.810306][    T1]  ? parameq+0x14d/0x170
[   10.814960][    T1]  ? parse_args+0x9c3/0xad0
[   10.819721][    T1]  ? trace_kmalloc+0x2a/0xf0
[   10.824825][    T1]  ? rcu_is_watching+0x15/0xb0
[   10.830024][    T1]  do_initcall_level+0x10a/0x1a0
[   10.835443][    T1]  ? kernel_init+0x22/0x1d0
[   10.840382][    T1]  do_initcalls+0x59/0xa0
[   10.845114][    T1]  kernel_init_freeable+0x29d/0x3e0
[   10.851473][    T1]  ? __pfx_kernel_init+0x10/0x10
[   10.856837][    T1]  kernel_init+0x22/0x1d0
[   10.861490][    T1]  ? __pfx_kernel_init+0x10/0x10
[   10.866649][    T1]  ret_from_fork+0x514/0xb70
[   10.871689][    T1]  ? __pfx_ret_from_fork+0x10/0x10
[   10.877021][    T1]  ? __switch_to+0xc89/0x1420
[   10.882121][    T1]  ? __pfx_kernel_init+0x10/0x10
[   10.887137][    T1]  ret_from_fork_asm+0x1a/0x30
[   10.892334][    T1]  </TASK>
[   10.895398][    T1] Kernel panic - not syncing: kernel: panic_on_warn set ...
[   10.902283][    T1] CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
[   10.902283][    T1] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
[   10.902283][    T1] Call Trace:
[   10.902283][    T1]  <TASK>
[   10.902283][    T1]  vpanic+0x56c/0xa60
[   10.902283][    T1]  ? __pfx__printk+0x10/0x10
[   10.902283][    T1]  ? __pfx_vpanic+0x10/0x10
[   10.902283][    T1]  ? is_bpf_text_address+0x292/0x2b0
[   10.902283][    T1]  ? is_bpf_text_address+0x26/0x2b0
[   10.902283][    T1]  panic+0xc5/0xd0
[   10.902283][    T1]  ? __pfx_panic+0x10/0x10
[   10.902283][    T1]  ? ret_from_fork_asm+0x1a/0x30
[   10.902283][    T1]  __warn+0x315/0x4c0
[   10.902283][    T1]  ? drm_mode_config_validate+0x1c6d/0x1e60
[   10.902283][    T1]  ? drm_mode_config_validate+0x1c6d/0x1e60
[   10.902283][    T1]  __report_bug+0x276/0x570
[   10.991867][    T1]  ? drm_mode_config_validate+0x1c6d/0x1e60
[   10.991867][    T1]  ? __pfx___report_bug+0x10/0x10
[   10.991867][    T1]  ? _raw_spin_unlock_irqrestore+0x30/0x80
[   10.991867][    T1]  ? lockdep_hardirqs_on+0x7a/0x110
[   10.991867][    T1]  ? rt_mutex_slowunlock+0x4ee/0xa20
[   10.991867][    T1]  report_bug_entry+0x19a/0x290
[   10.991867][    T1]  ? drm_mode_config_validate+0x1cae/0x1e60
[   10.991867][    T1]  ? drm_mode_config_validate+0x1cb3/0x1e60
[   10.991867][    T1]  handle_bug+0xce/0x200
[   10.991867][    T1]  exc_invalid_op+0x1a/0x50
[   10.991867][    T1]  asm_exc_invalid_op+0x1a/0x20
[   10.991867][    T1] RIP: 0010:drm_mode_config_validate+0x1cae/0x1e60
[   10.991867][    T1] Code: 0f 85 ae 00 00 00 4d 8d 77 10 8b 6d 00 4c 89 f0 48 c1 e8 03 80 3c 18 00 74 08 4c 89 f7 e8 9a 52 ab fc 49 8b 16 4c 89 ef 89 ee <67> 48 0f b9 3a eb 05 e8 b6 a6 3e fc 49 bd 00 00 00 00 00 fc ff df
[   11.091841][    T1] RSP: 0000:ffffc90000067810 EFLAGS: 00010246
[   11.091841][    T1] RAX: 1ffff11004b7e608 RBX: dffffc0000000000 RCX: ffff88801c6fddc0
[   11.091841][    T1] RDX: ffff88802664ba00 RSI: 0000000000000023 RDI: ffffffff8fdd4690
[   11.091841][    T1] RBP: 0000000000000023 R08: 0000000000000000 R09: 0000000000000000
[   11.091841][    T1] R10: dffffc0000000000 R11: fffffbfff1fa3f90 R12: dffffc0000000000
[   11.091841][    T1] R13: ffffffff8fdd4690 R14: ffff888025bf3040 R15: ffff888025bf3030
[   11.091841][    T1]  ? debugfs_create_file_full+0x3f/0x60
[   11.091841][    T1]  drm_dev_register+0x7f/0xd80
[   11.091841][    T1]  vkms_create+0x40d/0x4f0
[   11.091841][    T1]  ? __pfx_vkms_init+0x10/0x10
[   11.091841][    T1]  vkms_init+0x57/0x80
[   11.091841][    T1]  do_one_initcall+0x250/0x870
[   11.091841][    T1]  ? __pfx_vkms_init+0x10/0x10
[   11.091841][    T1]  ? __pfx_do_one_initcall+0x10/0x10
[   11.191821][    T1]  ? __pfx___schedule+0x10/0x10
[   11.191821][    T1]  ? irqentry_exit+0x218/0x910
[   11.191821][    T1]  ? lockdep_hardirqs_on+0x7a/0x110
[   11.191821][    T1]  ? irqentry_exit+0x218/0x910
[   11.191821][    T1]  ? trace_irq_disable+0x3b/0x140
[   11.191821][    T1]  ? strlen+0x2e/0x70
[   11.191821][    T1]  ? next_arg+0x4a0/0x5e0
[   11.191821][    T1]  ? parameq+0x14d/0x170
[   11.191821][    T1]  ? parse_args+0x9c3/0xad0
[   11.191821][    T1]  ? trace_kmalloc+0x2a/0xf0
[   11.191821][    T1]  ? rcu_is_watching+0x15/0xb0
[   11.191821][    T1]  do_initcall_level+0x10a/0x1a0
[   11.191821][    T1]  ? kernel_init+0x22/0x1d0
[   11.191821][    T1]  do_initcalls+0x59/0xa0
[   11.191821][    T1]  kernel_init_freeable+0x29d/0x3e0
[   11.191821][    T1]  ? __pfx_kernel_init+0x10/0x10
[   11.191821][    T1]  kernel_init+0x22/0x1d0
[   11.191821][    T1]  ? __pfx_kernel_init+0x10/0x10
[   11.191821][    T1]  ret_from_fork+0x514/0xb70
[   11.191821][    T1]  ? __pfx_ret_from_fork+0x10/0x10
[   11.291769][    T1]  ? __switch_to+0xc89/0x1420
[   11.291769][    T1]  ? __pfx_kernel_init+0x10/0x10
[   11.291769][    T1]  ret_from_fork_asm+0x1a/0x30
[   11.291769][    T1]  </TASK>
[   11.291769][    T1] Kernel Offset: disabled
[   11.291769][    T1] Rebooting in 86400 seconds..


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-build3374586982=/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='go1.26.0'
GOWORK=''
PKG_CONFIG='pkg-config'

git status (err=<nil>)
HEAD detached at e611ffe1caa
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=e611ffe1caa28a0228c8f3642cc768f0dba3dd0c -X github.com/google/syzkaller/prog.gitRevisionDate=20260731-140359"  ./sys/syz-sysgen | grep -q false || go install -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=e611ffe1caa28a0228c8f3642cc768f0dba3dd0c -X github.com/google/syzkaller/prog.gitRevisionDate=20260731-140359"  ./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=e611ffe1caa28a0228c8f3642cc768f0dba3dd0c -X github.com/google/syzkaller/prog.gitRevisionDate=20260731-140359"  -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=\"e611ffe1caa28a0228c8f3642cc768f0dba3dd0c\"
/usr/bin/ld: /tmp/cctJeKL4.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=13611079580000


Tested on:

commit:         3d08ff75 Add linux-next specific files for 20260810
git tree:       linux-next
kernel config:  https://syzkaller.appspot.com/x/.config?x=36c8c769cb13cc46
dashboard link: https://syzkaller.appspot.com/bug?extid=97a62389c5611b0477f3
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=108c6149580000