Re: [syzbot] [fs?] WARNING in nsproxy_ns_active_put

[syzbot <syzbot+0b2e79f91ff6579bfa5b@syzkaller.appspotmail.com>]

Hello,

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

970707b2'
[   21.974518][    T1] zswap: loaded using pool 842
[   21.982912][    T1] Demotion targets for Node 0: null
[   21.988200][    T1] Demotion targets for Node 1: null
[   21.993522][    T1] debug_vm_pgtable: [debug_vm_pgtable         ]: Validating architecture page table helpers
[   24.797559][    T1] Key type .fscrypt registered
[   24.802517][    T1] Key type fscrypt-provisioning registered
[   24.811687][    T1] kAFS: Red Hat AFS client v0.1 registering.
[   24.837336][    T1] Btrfs loaded, assert=on, zoned=yes, fsverity=yes
[   24.844500][    T1] Key type big_key registered
[   24.849260][    T1] Key type encrypted registered
[   24.854106][    T1] AppArmor: AppArmor sha256 policy hashing enabled
[   24.860731][    T1] ima: No TPM chip found, activating TPM-bypass!
[   24.867175][    T1] Loading compiled-in module X.509 certificates
[   24.894366][    T1] Loaded X.509 cert 'Build time autogenerated kernel key: de56e482b03ecd8d239a6590830ee0f7970707b2'
[   24.905348][    T1] ima: Allocated hash algorithm: sha256
[   24.911357][    T1] ima: No architecture policies found
[   24.917173][    T1] evm: Initialising EVM extended attributes:
[   24.923151][    T1] evm: security.selinux (disabled)
[   24.928238][    T1] evm: security.SMACK64 (disabled)
[   24.933355][    T1] evm: security.SMACK64EXEC (disabled)
[   24.938815][    T1] evm: security.SMACK64TRANSMUTE (disabled)
[   24.944683][    T1] evm: security.SMACK64MMAP (disabled)
[   24.950134][    T1] evm: security.apparmor
[   24.954370][    T1] evm: security.ima
[   24.958145][    T1] evm: security.capability
[   24.962553][    T1] evm: HMAC attrs: 0x1
[   24.968988][    T1] PM:   Magic number: 1:272:986
[   24.973842][    T1] net rose20: hash matches
[   24.978361][    T1] dsp_pipeline hwec: hash matches
[   24.984302][    T1] netconsole: network logging started
[   24.990369][    T1] gtp: GTP module loaded (pdp ctx size 128 bytes)
[   25.002183][    T1] rdma_rxe: loaded
[   25.007915][    T1] cfg80211: Loading compiled-in X.509 certificates for regulatory database
[   25.019009][    T1] Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
[   25.026972][    T1] Loaded X.509 cert 'wens: 61c038651aabdcf94bd0ac7ff06c7248db18c600'
[   25.038011][    T1] clk: Disabling unused clocks
[   25.043143][    T1] ALSA device list:
[   25.044532][  T793] faux_driver regulatory: Direct firmware load for regulatory.db failed with error -2
[   25.046952][    T1]   #0: Dummy 1
[   25.046964][    T1]   #1: Loopback 1
[   25.056659][  T793] faux_driver regulatory: Falling back to sysfs fallback for: regulatory.db
[   25.072704][    T1]   #2: Virtual MIDI Card 1
[   25.080464][    T1] check access for rdinit=/init failed: -2, ignoring
[   25.087134][    T1] md: Waiting for all devices to be available before autodetect
[   25.094786][    T1] md: If you don't use raid, use raid=noautodetect
[   25.101311][    T1] md: Autodetecting RAID arrays.
[   25.106328][    T1] md: autorun ...
[   25.109974][    T1] md: ... autorun DONE.
[   25.202934][    T1] EXT4-fs (sda1): orphan cleanup on readonly fs
[   25.211522][    T1] EXT4-fs (sda1): mounted filesystem 4f91c6db-4997-4bb4-91b8-7e83a20c1bf1 ro with ordered data mode. Quota mode: none.
[   25.224301][    T1] VFS: Mounted root (ext4 filesystem) readonly on device 8:1.
[   25.234167][    T1] devtmpfs: mounted
[   25.311718][    T1] Freeing unused kernel image (initmem) memory: 26112K
[   25.322460][    T1] Write protecting the kernel read-only data: 212992k
[   25.341592][    T1] Freeing unused kernel image (text/rodata gap) memory: 1436K
[   25.353977][    T1] Freeing unused kernel image (rodata/data gap) memory: 1240K
[   25.458459][    T1] x86/mm: Checked W+X mappings: passed, no W+X pages found.
[   25.466412][    T1] x86/mm: Checking user space page tables
[   25.555644][    T1] x86/mm: Checked W+X mappings: passed, no W+X pages found.
[   25.568271][    T1] Failed to set sysctl parameter 'max_rcu_stall_to_panic=1': parameter not found
[   25.578126][    T1] Run /sbin/init as init process
[   25.833630][ T5157] mount (5157) used greatest stack depth: 23816 bytes left
[   25.885026][ T5158] EXT4-fs (sda1): re-mounted 4f91c6db-4997-4bb4-91b8-7e83a20c1bf1 r/w.
[   25.897827][ T5158] mount (5158) used greatest stack depth: 23624 bytes left
mount: mounting devtmpfs on /dev failed: Device or resource busy
mount: mounting smackfs on /sys/fs/smackfs failed: No such file or directory
mount: mounting selinuxfs on /sys/fs/selinux failed: No such file or directory
[   26.026823][ T5162] mount (5162) used greatest stack depth: 21672 bytes left
Starting syslogd: OK
Starting acpid: [   26.448559][ T5177] acpid (5177) used greatest stack depth: 20968 bytes left
OK
Starting klogd: OK
Running sysctl: OK
Populating /dev using udev: [   27.039741][ T5192] udevd[5192]: starting version 3.2.14
[   27.206253][ T5193] udevd[5193]: starting eudev-3.2.14
[   27.210256][ T5192] udevd (5192) used greatest stack depth: 18088 bytes left
done
Starting system message bus: done
Starting iptables: OK
Starting network: OK
Starting dhcpcd...
dhcpcd-10.2.0 starting
[   46.776298][ T5487] ------------[ cut here ]------------
[   46.781953][ T5487] WARNING: ./include/linux/ns_common.h:314 at nsfs_evict+0x18e/0x200, CPU#1: dhcpcd/5487
[   46.792403][ T5487] Modules linked in:
[   46.796337][ T5487] CPU: 1 UID: 0 PID: 5487 Comm: dhcpcd Not tainted syzkaller #0 PREEMPT(full) 
[   46.805316][ T5487] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
[   46.815409][ T5487] RIP: 0010:nsfs_evict+0x18e/0x200
[   46.820563][ T5487] Code: 4d 8b 1e 48 89 df 5b 41 5c 41 5d 41 5e 41 5f 5d 41 ff e3 cc cc cc e8 01 c7 76 ff 90 0f 0b 90 e9 1f ff ff ff e8 f3 c6 76 ff 90 <0f> 0b 90 e9 42 ff ff ff e8 e5 c6 76 ff 90 0f 0b 90 e9 72 ff ff ff
[   46.840207][ T5487] RSP: 0018:ffffc900039afa28 EFLAGS: 00010293
[   46.846262][ T5487] RAX: ffffffff824b0e3d RBX: ffffffff9a180fd8 RCX: ffff88802e6d1e80
[   46.854272][ T5487] RDX: 0000000000000000 RSI: 00000000effffff8 RDI: 00000000effffff8
[   46.862272][ T5487] RBP: 00000000effffff8 R08: ffffffff9a181093 R09: 1ffffffff3430212
[   46.870298][ T5487] R10: dffffc0000000000 R11: fffffbfff3430213 R12: dffffc0000000000
[   46.878265][ T5487] R13: 1ffffffff34301fe R14: ffff88807a7cf248 R15: ffffffff9a180ff0
[   46.886301][ T5487] FS:  00007f5b3bc92740(0000) GS:ffff888125b78000(0000) knlGS:0000000000000000
[   46.895267][ T5487] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   46.901937][ T5487] CR2: 0000563ddc89c4a0 CR3: 000000006f210000 CR4: 00000000003526f0
[   46.909942][ T5487] Call Trace:
[   46.913233][ T5487]  <TASK>
[   46.916163][ T5487]  ? __pfx_nsfs_evict+0x10/0x10
[   46.921065][ T5487]  evict+0x5f4/0xae0
[   46.925002][ T5487]  ? __pfx_evict+0x10/0x10
[   46.929539][ T5487]  ? _raw_spin_unlock+0x28/0x50
[   46.934391][ T5487]  ? iput+0xce7/0x1050
[   46.938444][ T5487]  __dentry_kill+0x209/0x660
[   46.943076][ T5487]  ? dput+0x37/0x2b0
[   46.946973][ T5487]  dput+0x19f/0x2b0
[   46.950799][ T5487]  path_put+0x39/0x60
[   46.954833][ T5487]  vfs_statx+0x36e/0x550
[   46.959106][ T5487]  ? __pfx_vfs_statx+0x10/0x10
[   46.963873][ T5487]  ? strncpy_from_user+0x150/0x2c0
[   46.969019][ T5487]  ? getname_flags+0x1e5/0x540
[   46.973824][ T5487]  vfs_fstatat+0x118/0x170
[   46.978223][ T5487]  __x64_sys_newfstatat+0x116/0x190
[   46.983447][ T5487]  ? __pfx___x64_sys_newfstatat+0x10/0x10
[   46.989202][ T5487]  ? do_syscall_64+0xbe/0xfa0
[   46.993883][ T5487]  do_syscall_64+0xfa/0xfa0
[   46.998365][ T5487]  ? entry_SYSCALL_64_after_hwframe+0x77/0x7f
[   47.004477][ T5487]  ? clear_bhb_loop+0x60/0xb0
[   47.009189][ T5487]  entry_SYSCALL_64_after_hwframe+0x77/0x7f
[   47.015094][ T5487] RIP: 0033:0x7f5b3bd86b0a
[   47.019580][ T5487] Code: 48 8b 15 f1 f2 0d 00 f7 d8 64 89 02 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 41 89 ca b8 06 01 00 00 0f 05 <3d> 00 f0 ff ff 77 07 31 c0 c3 0f 1f 40 00 48 8b 15 b9 f2 0d 00 f7
[   47.039327][ T5487] RSP: 002b:00007ffc209e1718 EFLAGS: 00000246 ORIG_RAX: 0000000000000106
[   47.047744][ T5487] RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f5b3bd86b0a
[   47.055741][ T5487] RDX: 00007ffc209e1720 RSI: 0000563ddc8c4557 RDI: 00000000ffffff9c
[   47.063747][ T5487] RBP: 00007ffc209e3eb8 R08: 0000000000000000 R09: 0000000000000000
[   47.071763][ T5487] R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc209e2890
[   47.079775][ T5487] R13: 0000563e1752d8a0 R14: 0000000000001000 R15: 00007f5b3bc926c8
[   47.087762][ T5487]  </TASK>
[   47.090819][ T5487] Kernel panic - not syncing: kernel: panic_on_warn set ...
[   47.098094][ T5487] CPU: 1 UID: 0 PID: 5487 Comm: dhcpcd Not tainted syzkaller #0 PREEMPT(full) 
[   47.107008][ T5487] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
[   47.117042][ T5487] Call Trace:
[   47.120305][ T5487]  <TASK>
[   47.123217][ T5487]  dump_stack_lvl+0x99/0x250
[   47.127804][ T5487]  ? __asan_memcpy+0x40/0x70
[   47.132372][ T5487]  ? __pfx_dump_stack_lvl+0x10/0x10
[   47.137549][ T5487]  ? __pfx__printk+0x10/0x10
[   47.142123][ T5487]  vpanic+0x237/0x6d0
[   47.146171][ T5487]  ? __pfx_vpanic+0x10/0x10
[   47.150648][ T5487]  ? is_bpf_text_address+0x292/0x2b0
[   47.155913][ T5487]  ? is_bpf_text_address+0x26/0x2b0
[   47.161096][ T5487]  panic+0xb9/0xc0
[   47.164798][ T5487]  ? __pfx_panic+0x10/0x10
[   47.169202][ T5487]  __warn+0x334/0x4c0
[   47.173160][ T5487]  ? nsfs_evict+0x18e/0x200
[   47.177641][ T5487]  ? nsfs_evict+0x18e/0x200
[   47.182126][ T5487]  report_bug+0x2be/0x4f0
[   47.186436][ T5487]  ? nsfs_evict+0x18e/0x200
[   47.190915][ T5487]  ? nsfs_evict+0x18e/0x200
[   47.195395][ T5487]  ? nsfs_evict+0x190/0x200
[   47.199876][ T5487]  handle_bug+0x84/0x160
[   47.204114][ T5487]  exc_invalid_op+0x1a/0x50
[   47.208629][ T5487]  asm_exc_invalid_op+0x1a/0x20
[   47.213486][ T5487] RIP: 0010:nsfs_evict+0x18e/0x200
[   47.218605][ T5487] Code: 4d 8b 1e 48 89 df 5b 41 5c 41 5d 41 5e 41 5f 5d 41 ff e3 cc cc cc e8 01 c7 76 ff 90 0f 0b 90 e9 1f ff ff ff e8 f3 c6 76 ff 90 <0f> 0b 90 e9 42 ff ff ff e8 e5 c6 76 ff 90 0f 0b 90 e9 72 ff ff ff
[   47.238215][ T5487] RSP: 0018:ffffc900039afa28 EFLAGS: 00010293
[   47.244897][ T5487] RAX: ffffffff824b0e3d RBX: ffffffff9a180fd8 RCX: ffff88802e6d1e80
[   47.252860][ T5487] RDX: 0000000000000000 RSI: 00000000effffff8 RDI: 00000000effffff8
[   47.260822][ T5487] RBP: 00000000effffff8 R08: ffffffff9a181093 R09: 1ffffffff3430212
[   47.268783][ T5487] R10: dffffc0000000000 R11: fffffbfff3430213 R12: dffffc0000000000
[   47.276756][ T5487] R13: 1ffffffff34301fe R14: ffff88807a7cf248 R15: ffffffff9a180ff0
[   47.284739][ T5487]  ? nsfs_evict+0x18d/0x200
[   47.289248][ T5487]  ? nsfs_evict+0x18d/0x200
[   47.293742][ T5487]  ? __pfx_nsfs_evict+0x10/0x10
[   47.298581][ T5487]  evict+0x5f4/0xae0
[   47.302483][ T5487]  ? __pfx_evict+0x10/0x10
[   47.306894][ T5487]  ? _raw_spin_unlock+0x28/0x50
[   47.311737][ T5487]  ? iput+0xce7/0x1050
[   47.315801][ T5487]  __dentry_kill+0x209/0x660
[   47.320380][ T5487]  ? dput+0x37/0x2b0
[   47.324265][ T5487]  dput+0x19f/0x2b0
[   47.328059][ T5487]  path_put+0x39/0x60
[   47.332030][ T5487]  vfs_statx+0x36e/0x550
[   47.336284][ T5487]  ? __pfx_vfs_statx+0x10/0x10
[   47.341048][ T5487]  ? strncpy_from_user+0x150/0x2c0
[   47.346174][ T5487]  ? getname_flags+0x1e5/0x540
[   47.350940][ T5487]  vfs_fstatat+0x118/0x170
[   47.355369][ T5487]  __x64_sys_newfstatat+0x116/0x190
[   47.360640][ T5487]  ? __pfx___x64_sys_newfstatat+0x10/0x10
[   47.366383][ T5487]  ? do_syscall_64+0xbe/0xfa0
[   47.371078][ T5487]  do_syscall_64+0xfa/0xfa0
[   47.375592][ T5487]  ? entry_SYSCALL_64_after_hwframe+0x77/0x7f
[   47.381648][ T5487]  ? clear_bhb_loop+0x60/0xb0
[   47.386425][ T5487]  entry_SYSCALL_64_after_hwframe+0x77/0x7f
[   47.392748][ T5487] RIP: 0033:0x7f5b3bd86b0a
[   47.397245][ T5487] Code: 48 8b 15 f1 f2 0d 00 f7 d8 64 89 02 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 41 89 ca b8 06 01 00 00 0f 05 <3d> 00 f0 ff ff 77 07 31 c0 c3 0f 1f 40 00 48 8b 15 b9 f2 0d 00 f7
[   47.416866][ T5487] RSP: 002b:00007ffc209e1718 EFLAGS: 00000246 ORIG_RAX: 0000000000000106
[   47.425277][ T5487] RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f5b3bd86b0a
[   47.433236][ T5487] RDX: 00007ffc209e1720 RSI: 0000563ddc8c4557 RDI: 00000000ffffff9c
[   47.441215][ T5487] RBP: 00007ffc209e3eb8 R08: 0000000000000000 R09: 0000000000000000
[   47.449171][ T5487] R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc209e2890
[   47.457124][ T5487] R13: 0000563e1752d8a0 R14: 0000000000001000 R15: 00007f5b3bc926c8
[   47.465097][ T5487]  </TASK>
[   47.468346][ T5487] Kernel Offset: disabled
[   47.472660][ T5487] 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-build1222549954=/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='go1.24.4'
GOWORK=''
PKG_CONFIG='pkg-config'

git status (err=<nil>)
HEAD detached at a6c9c731229
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=a6c9c7312290da5bca2fc1be4872a7aeefb6e3ea -X github.com/google/syzkaller/prog.gitRevisionDate=20251104-181356"  ./sys/syz-sysgen | grep -q false || go install -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=a6c9c7312290da5bca2fc1be4872a7aeefb6e3ea -X github.com/google/syzkaller/prog.gitRevisionDate=20251104-181356"  ./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=a6c9c7312290da5bca2fc1be4872a7aeefb6e3ea -X github.com/google/syzkaller/prog.gitRevisionDate=20251104-181356"  -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=\"a6c9c7312290da5bca2fc1be4872a7aeefb6e3ea\"
/usr/bin/ld: /tmp/ccl2NrsB.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=17b05084580000


Tested on:

commit:         9c0826a5 Add linux-next specific files for 20251107
git tree:       linux-next
kernel config:  https://syzkaller.appspot.com/x/.config?x=4f8fcc6438a785e7
dashboard link: https://syzkaller.appspot.com/bug?extid=0b2e79f91ff6579bfa5b
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=11e03812580000