Extracting prog: 2m38.510369951s
Minimizing prog: 11m15.511906643s
Simplifying prog options: 0s
Extracting C: 2m32.207720733s
Simplifying C: 24m14.485807949s


extracting reproducer from 30 programs
first checking the prog from the crash report
single: executing 1 programs separately with timeout 30s
testing program (duration=30s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE-unshare-fsmount
detailed listing:
executing program 0:
unshare(0x2040600)
r0 = fsopen(&(0x7f0000000040)='cgroup2\x00', 0x1)
fsconfig$FSCONFIG_CMD_CREATE(r0, 0x6, 0x0, 0x0, 0x0)
unshare(0x2000400)
fsmount(r0, 0x0, 0x0)

program crashed: WARNING: suspicious RCU usage in kernfs_node_dentry
single: successfully extracted reproducer
found reproducer with 5 syscalls
minimizing guilty program
testing program (duration=53.302081699s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE-unshare
detailed listing:
executing program 0:
unshare(0x2040600)
r0 = fsopen(&(0x7f0000000040)='cgroup2\x00', 0x1)
fsconfig$FSCONFIG_CMD_CREATE(r0, 0x6, 0x0, 0x0, 0x0)
unshare(0x2000400)

program crashed: WARNING: suspicious RCU usage in kernfs_node_dentry
testing program (duration=53.302081699s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE
detailed listing:
executing program 0:
unshare(0x2040600)
r0 = fsopen(&(0x7f0000000040)='cgroup2\x00', 0x1)
fsconfig$FSCONFIG_CMD_CREATE(r0, 0x6, 0x0, 0x0, 0x0)

program crashed: WARNING: suspicious RCU usage in kernfs_node_dentry
testing program (duration=53.302081699s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen
detailed listing:
executing program 0:
unshare(0x2040600)
fsopen(&(0x7f0000000040)='cgroup2\x00', 0x1)

program did not crash
testing program (duration=53.302081699s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsconfig$FSCONFIG_CMD_CREATE
detailed listing:
executing program 0:
unshare(0x2040600)
fsconfig$FSCONFIG_CMD_CREATE(0xffffffffffffffff, 0x6, 0x0, 0x0, 0x0)

program did not crash
testing program (duration=53.302081699s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): fsopen-fsconfig$FSCONFIG_CMD_CREATE
detailed listing:
executing program 0:
r0 = fsopen(&(0x7f0000000040)='cgroup2\x00', 0x1)
fsconfig$FSCONFIG_CMD_CREATE(r0, 0x6, 0x0, 0x0, 0x0)

program did not crash
testing program (duration=53.302081699s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE
detailed listing:
executing program 0:
unshare(0x2040600)
r0 = fsopen(0x0, 0x1)
fsconfig$FSCONFIG_CMD_CREATE(r0, 0x6, 0x0, 0x0, 0x0)

program did not crash
extracting C reproducer
testing compiled C program (duration=53.302081699s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE
program crashed: WARNING: suspicious RCU usage in kernfs_node_dentry
simplifying C reproducer
testing compiled C program (duration=53.302081699s, {Threaded:false Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE
program crashed: WARNING: suspicious RCU usage in kernfs_node_dentry
testing compiled C program (duration=53.302081699s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:false Cgroups:false BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE
program did not crash
testing compiled C program (duration=53.302081699s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE
program crashed: WARNING: suspicious RCU usage in kernfs_node_dentry
testing compiled C program (duration=53.302081699s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:true Sysctl:true Swap:false UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE
program did not crash
testing compiled C program (duration=53.302081699s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE
program crashed: WARNING: suspicious RCU usage in kernfs_node_dentry
testing compiled C program (duration=53.302081699s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE
program crashed: WARNING: suspicious RCU usage in kernfs_node_dentry
testing compiled C program (duration=53.302081699s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE
program crashed: WARNING: suspicious RCU usage in kernfs_node_dentry
testing compiled C program (duration=53.302081699s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE
program did not crash
testing compiled C program (duration=53.302081699s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:true BinfmtMisc:false CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE
program crashed: WARNING: suspicious RCU usage in kernfs_node_dentry
testing compiled C program (duration=53.302081699s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:true BinfmtMisc:false CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE
program crashed: WARNING: suspicious RCU usage in kernfs_node_dentry
testing compiled C program (duration=53.302081699s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:true BinfmtMisc:false CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE
program crashed: WARNING: suspicious RCU usage in kernfs_node_dentry
testing compiled C program (duration=53.302081699s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:true BinfmtMisc:false CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE
program crashed: WARNING: suspicious RCU usage in kernfs_node_dentry
testing compiled C program (duration=53.302081699s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:true BinfmtMisc:false CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE
program crashed: WARNING: suspicious RCU usage in kernfs_node_dentry
testing compiled C program (duration=53.302081699s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:true BinfmtMisc:false CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:false Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE
program crashed: WARNING: suspicious RCU usage in kernfs_node_dentry
testing compiled C program (duration=53.302081699s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:true BinfmtMisc:false CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:false Swap:true UseTmpDir:true HandleSegv:false Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE
program crashed: WARNING: suspicious RCU usage in kernfs_node_dentry
testing compiled C program (duration=53.302081699s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:true BinfmtMisc:false CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:false Swap:false UseTmpDir:true HandleSegv:false Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): unshare-fsopen-fsconfig$FSCONFIG_CMD_CREATE
program crashed: WARNING: suspicious RCU usage in kernfs_node_dentry
reproducing took 40m40.715832451s
repro crashed as (corrupted=false):
=============================
WARNING: suspicious RCU usage
6.14.0-rc2-next-20250217-syzkaller #0 Not tainted
-----------------------------
fs/kernfs/mount.c:243 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
3 locks held by syz-executor382/5832:
 #0: ffff88805ad01470 (&fc->uapi_mutex){+.+.}-{4:4}, at: __do_sys_fsconfig fs/fsopen.c:465 [inline]
 #0: ffff88805ad01470 (&fc->uapi_mutex){+.+.}-{4:4}, at: __se_sys_fsconfig+0x9b2/0xf60 fs/fsopen.c:344
 #1: ffff88807cd4c0e0 (&type->s_umount_key#46){+.+.}-{4:4}, at: __super_lock fs/super.c:56 [inline]
 #1: ffff88807cd4c0e0 (&type->s_umount_key#46){+.+.}-{4:4}, at: super_lock+0x196/0x400 fs/super.c:120
 #2: ffff88801bef7148 (&root->kernfs_rwsem){++++}-{4:4}, at: class_rwsem_read_constructor include/linux/rwsem.h:241 [inline]
 #2: ffff88801bef7148 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_node_dentry+0xc3/0x2d0 fs/kernfs/mount.c:223

stack backtrace:
CPU: 1 UID: 0 PID: 5832 Comm: syz-executor382 Not tainted 6.14.0-rc2-next-20250217-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x226/0x340 kernel/locking/lockdep.c:6847
 kernfs_node_dentry+0x24b/0x2d0 fs/kernfs/mount.c:243
 cgroup_do_get_tree+0x248/0x390 kernel/cgroup/cgroup.c:2233
 cgroup_get_tree+0xbb/0x230 kernel/cgroup/cgroup.c:2272
 vfs_get_tree+0x90/0x2b0 fs/super.c:1759
 vfs_cmd_create+0xa0/0x1f0 fs/fsopen.c:225
 __do_sys_fsconfig fs/fsopen.c:467 [inline]
 __se_sys_fsconfig+0xa33/0xf60 fs/fsopen.c:344
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fde8a2dede9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 18 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff11833388 EFLAGS: 00000246 ORIG_RAX: 00000000000001af
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fde8a2dede9
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fde8a328036
R13: 00007fff118333c0 R14: 00007fff11833400 R15: 0000000000000000
 </TASK>

============================================
WARNING: possible recursive locking detected
6.14.0-rc2-next-20250217-syzkaller #0 Not tainted
--------------------------------------------
syz-executor382/5832 is trying to acquire lock:
ffff88801bef7148 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_dop_revalidate+0xa2/0x5d0 fs/kernfs/dir.c:1178

but task is already holding lock:
ffff88801bef7148 (&root->kernfs_rwsem){++++}-{4:4}, at: class_rwsem_read_constructor include/linux/rwsem.h:241 [inline]
ffff88801bef7148 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_node_dentry+0xc3/0x2d0 fs/kernfs/mount.c:223

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&root->kernfs_rwsem);
  lock(&root->kernfs_rwsem);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

3 locks held by syz-executor382/5832:
 #0: ffff88805ad01470 (&fc->uapi_mutex){+.+.}-{4:4}, at: __do_sys_fsconfig fs/fsopen.c:465 [inline]
 #0: ffff88805ad01470 (&fc->uapi_mutex){+.+.}-{4:4}, at: __se_sys_fsconfig+0x9b2/0xf60 fs/fsopen.c:344
 #1: ffff88807cd4c0e0 (&type->s_umount_key#46){+.+.}-{4:4}, at: __super_lock fs/super.c:56 [inline]
 #1: ffff88807cd4c0e0 (&type->s_umount_key#46){+.+.}-{4:4}, at: super_lock+0x196/0x400 fs/super.c:120
 #2: ffff88801bef7148 (&root->kernfs_rwsem){++++}-{4:4}, at: class_rwsem_read_constructor include/linux/rwsem.h:241 [inline]
 #2: ffff88801bef7148 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_node_dentry+0xc3/0x2d0 fs/kernfs/mount.c:223

stack backtrace:
CPU: 1 UID: 0 PID: 5832 Comm: syz-executor382 Not tainted 6.14.0-rc2-next-20250217-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_deadlock_bug+0x483/0x620 kernel/locking/lockdep.c:3039
 check_deadlock kernel/locking/lockdep.c:3091 [inline]
 validate_chain+0x15e2/0x5920 kernel/locking/lockdep.c:3893
 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
 down_read+0xb1/0xa40 kernel/locking/rwsem.c:1524
 kernfs_dop_revalidate+0xa2/0x5d0 fs/kernfs/dir.c:1178
 d_revalidate fs/namei.c:923 [inline]
 lookup_dcache fs/namei.c:1651 [inline]
 lookup_one_unlocked+0x23b/0x2d0 fs/namei.c:2972
 lookup_one_positive_unlocked fs/namei.c:3003 [inline]
 lookup_positive_unlocked+0x2b/0xb0 fs/namei.c:3043
 kernfs_node_dentry+0x139/0x2d0 fs/kernfs/mount.c:244
 cgroup_do_get_tree+0x248/0x390 kernel/cgroup/cgroup.c:2233
 cgroup_get_tree+0xbb/0x230 kernel/cgroup/cgroup.c:2272
 vfs_get_tree+0x90/0x2b0 fs/super.c:1759
 vfs_cmd_create+0xa0/0x1f0 fs/fsopen.c:225
 __do_sys_fsconfig fs/fsopen.c:467 [inline]
 __se_sys_fsconfig+0xa33/0xf60 fs/fsopen.c:344
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fde8a2dede9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 18 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff11833388 EFLAGS: 00000246 ORIG_RAX: 00000000000001af
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fde8a2dede9
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fde8a328036
R13: 00007fff118333c0 R14: 00007fff11833400 R15: 0000000000000000
 </TASK>

final repro crashed as (corrupted=false):
=============================
WARNING: suspicious RCU usage
6.14.0-rc2-next-20250217-syzkaller #0 Not tainted
-----------------------------
fs/kernfs/mount.c:243 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
3 locks held by syz-executor382/5832:
 #0: ffff88805ad01470 (&fc->uapi_mutex){+.+.}-{4:4}, at: __do_sys_fsconfig fs/fsopen.c:465 [inline]
 #0: ffff88805ad01470 (&fc->uapi_mutex){+.+.}-{4:4}, at: __se_sys_fsconfig+0x9b2/0xf60 fs/fsopen.c:344
 #1: ffff88807cd4c0e0 (&type->s_umount_key#46){+.+.}-{4:4}, at: __super_lock fs/super.c:56 [inline]
 #1: ffff88807cd4c0e0 (&type->s_umount_key#46){+.+.}-{4:4}, at: super_lock+0x196/0x400 fs/super.c:120
 #2: ffff88801bef7148 (&root->kernfs_rwsem){++++}-{4:4}, at: class_rwsem_read_constructor include/linux/rwsem.h:241 [inline]
 #2: ffff88801bef7148 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_node_dentry+0xc3/0x2d0 fs/kernfs/mount.c:223

stack backtrace:
CPU: 1 UID: 0 PID: 5832 Comm: syz-executor382 Not tainted 6.14.0-rc2-next-20250217-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x226/0x340 kernel/locking/lockdep.c:6847
 kernfs_node_dentry+0x24b/0x2d0 fs/kernfs/mount.c:243
 cgroup_do_get_tree+0x248/0x390 kernel/cgroup/cgroup.c:2233
 cgroup_get_tree+0xbb/0x230 kernel/cgroup/cgroup.c:2272
 vfs_get_tree+0x90/0x2b0 fs/super.c:1759
 vfs_cmd_create+0xa0/0x1f0 fs/fsopen.c:225
 __do_sys_fsconfig fs/fsopen.c:467 [inline]
 __se_sys_fsconfig+0xa33/0xf60 fs/fsopen.c:344
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fde8a2dede9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 18 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff11833388 EFLAGS: 00000246 ORIG_RAX: 00000000000001af
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fde8a2dede9
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fde8a328036
R13: 00007fff118333c0 R14: 00007fff11833400 R15: 0000000000000000
 </TASK>

============================================
WARNING: possible recursive locking detected
6.14.0-rc2-next-20250217-syzkaller #0 Not tainted
--------------------------------------------
syz-executor382/5832 is trying to acquire lock:
ffff88801bef7148 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_dop_revalidate+0xa2/0x5d0 fs/kernfs/dir.c:1178

but task is already holding lock:
ffff88801bef7148 (&root->kernfs_rwsem){++++}-{4:4}, at: class_rwsem_read_constructor include/linux/rwsem.h:241 [inline]
ffff88801bef7148 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_node_dentry+0xc3/0x2d0 fs/kernfs/mount.c:223

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&root->kernfs_rwsem);
  lock(&root->kernfs_rwsem);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

3 locks held by syz-executor382/5832:
 #0: ffff88805ad01470 (&fc->uapi_mutex){+.+.}-{4:4}, at: __do_sys_fsconfig fs/fsopen.c:465 [inline]
 #0: ffff88805ad01470 (&fc->uapi_mutex){+.+.}-{4:4}, at: __se_sys_fsconfig+0x9b2/0xf60 fs/fsopen.c:344
 #1: ffff88807cd4c0e0 (&type->s_umount_key#46){+.+.}-{4:4}, at: __super_lock fs/super.c:56 [inline]
 #1: ffff88807cd4c0e0 (&type->s_umount_key#46){+.+.}-{4:4}, at: super_lock+0x196/0x400 fs/super.c:120
 #2: ffff88801bef7148 (&root->kernfs_rwsem){++++}-{4:4}, at: class_rwsem_read_constructor include/linux/rwsem.h:241 [inline]
 #2: ffff88801bef7148 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_node_dentry+0xc3/0x2d0 fs/kernfs/mount.c:223

stack backtrace:
CPU: 1 UID: 0 PID: 5832 Comm: syz-executor382 Not tainted 6.14.0-rc2-next-20250217-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_deadlock_bug+0x483/0x620 kernel/locking/lockdep.c:3039
 check_deadlock kernel/locking/lockdep.c:3091 [inline]
 validate_chain+0x15e2/0x5920 kernel/locking/lockdep.c:3893
 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
 down_read+0xb1/0xa40 kernel/locking/rwsem.c:1524
 kernfs_dop_revalidate+0xa2/0x5d0 fs/kernfs/dir.c:1178
 d_revalidate fs/namei.c:923 [inline]
 lookup_dcache fs/namei.c:1651 [inline]
 lookup_one_unlocked+0x23b/0x2d0 fs/namei.c:2972
 lookup_one_positive_unlocked fs/namei.c:3003 [inline]
 lookup_positive_unlocked+0x2b/0xb0 fs/namei.c:3043
 kernfs_node_dentry+0x139/0x2d0 fs/kernfs/mount.c:244
 cgroup_do_get_tree+0x248/0x390 kernel/cgroup/cgroup.c:2233
 cgroup_get_tree+0xbb/0x230 kernel/cgroup/cgroup.c:2272
 vfs_get_tree+0x90/0x2b0 fs/super.c:1759
 vfs_cmd_create+0xa0/0x1f0 fs/fsopen.c:225
 __do_sys_fsconfig fs/fsopen.c:467 [inline]
 __se_sys_fsconfig+0xa33/0xf60 fs/fsopen.c:344
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fde8a2dede9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 18 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff11833388 EFLAGS: 00000246 ORIG_RAX: 00000000000001af
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fde8a2dede9
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fde8a328036
R13: 00007fff118333c0 R14: 00007fff11833400 R15: 0000000000000000
 </TASK>