Extracting prog: 2m22.754511142s
Minimizing prog: 8m41.050963779s
Simplifying prog options: 3m52.172067785s
Extracting C: 1m30.93205658s
Simplifying C: 0s


extracting reproducer from 1 programs
testing a last program of every proc
single: executing 1 programs separately with timeout 30s
testing program (duration=30s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 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}}): add_key$keyring-openat$comedi-mprotect-ioctl$COMEDI_INSNLIST
detailed listing:
executing program 0:
add_key$keyring(&(0x7f0000000000), 0x0, 0x0, 0x0, 0xfffffffffffffffb)
r0 = openat$comedi(0xffffffffffffff9c, &(0x7f0000000040)='/dev/comedi4\x00', 0x181001, 0x0)
mprotect(&(0x7f0000000000/0x4000)=nil, 0x4000, 0x1)
ioctl$COMEDI_INSNLIST(r0, 0x8010640b, &(0x7f0000000000)={0x0, 0x0})

program crashed: WARNING: suspicious RCU usage in proc_sys_compare
single: successfully extracted reproducer
found reproducer with 4 syscalls
minimizing guilty program
testing program (duration=44.259005206s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 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}}): add_key$keyring-openat$comedi-mprotect
detailed listing:
executing program 0:
add_key$keyring(&(0x7f0000000000), 0x0, 0x0, 0x0, 0xfffffffffffffffb)
openat$comedi(0xffffffffffffff9c, &(0x7f0000000040)='/dev/comedi4\x00', 0x181001, 0x0)
mprotect(&(0x7f0000000000/0x4000)=nil, 0x4000, 0x1)

program did not crash
testing program (duration=44.259005206s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 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}}): add_key$keyring-openat$comedi-ioctl$COMEDI_INSNLIST
detailed listing:
executing program 0:
add_key$keyring(&(0x7f0000000000), 0x0, 0x0, 0x0, 0xfffffffffffffffb)
r0 = openat$comedi(0xffffffffffffff9c, &(0x7f0000000040)='/dev/comedi4\x00', 0x181001, 0x0)
ioctl$COMEDI_INSNLIST(r0, 0x8010640b, &(0x7f0000000000)={0x0, 0x0})

program crashed: WARNING: suspicious RCU usage in proc_sys_compare
testing program (duration=44.259005206s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 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}}): add_key$keyring-ioctl$COMEDI_INSNLIST
detailed listing:
executing program 0:
add_key$keyring(&(0x7f0000000000), 0x0, 0x0, 0x0, 0xfffffffffffffffb)
ioctl$COMEDI_INSNLIST(0xffffffffffffffff, 0x8010640b, &(0x7f0000000000)={0x0, 0x0})

program did not crash
testing program (duration=44.259005206s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 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}}): openat$comedi-ioctl$COMEDI_INSNLIST
detailed listing:
executing program 0:
r0 = openat$comedi(0xffffffffffffff9c, &(0x7f0000000040)='/dev/comedi4\x00', 0x181001, 0x0)
ioctl$COMEDI_INSNLIST(r0, 0x8010640b, &(0x7f0000000000)={0x0, 0x0})

program did not crash
testing program (duration=44.259005206s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 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}}): add_key$keyring-openat$comedi-ioctl$COMEDI_INSNLIST
detailed listing:
executing program 0:
add_key$keyring(0x0, 0x0, 0x0, 0x0, 0xfffffffffffffffb)
r0 = openat$comedi(0xffffffffffffff9c, &(0x7f0000000040)='/dev/comedi4\x00', 0x181001, 0x0)
ioctl$COMEDI_INSNLIST(r0, 0x8010640b, &(0x7f0000000000)={0x0, 0x0})

program did not crash
testing program (duration=44.259005206s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 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}}): add_key$keyring-openat$comedi-ioctl$COMEDI_INSNLIST
detailed listing:
executing program 0:
add_key$keyring(&(0x7f0000000000), 0x0, 0x0, 0x0, 0xfffffffffffffffb)
r0 = openat$comedi(0xffffffffffffff9c, 0x0, 0x181001, 0x0)
ioctl$COMEDI_INSNLIST(r0, 0x8010640b, &(0x7f0000000000)={0x0, 0x0})

program did not crash
testing program (duration=44.259005206s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 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}}): add_key$keyring-openat$comedi-ioctl$COMEDI_INSNLIST
detailed listing:
executing program 0:
add_key$keyring(&(0x7f0000000000), 0x0, 0x0, 0x0, 0xfffffffffffffffb)
r0 = openat$comedi(0xffffffffffffff9c, &(0x7f0000000040)='/dev/comedi4\x00', 0x181001, 0x0)
ioctl$COMEDI_INSNLIST(r0, 0x8010640b, 0x0)

program crashed: WARNING: suspicious RCU usage in proc_sys_compare
extracting C reproducer
testing compiled C program (duration=44.259005206s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 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}}): add_key$keyring-openat$comedi-ioctl$COMEDI_INSNLIST
program did not crash
simplifying guilty program options
testing program (duration=44.259005206s, {Threaded:false Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): add_key$keyring-openat$comedi-ioctl$COMEDI_INSNLIST
detailed listing:
executing program 0:
add_key$keyring(&(0x7f0000000000), 0x0, 0x0, 0x0, 0xfffffffffffffffb)
r0 = openat$comedi(0xffffffffffffff9c, &(0x7f0000000040)='/dev/comedi4\x00', 0x181001, 0x0)
ioctl$COMEDI_INSNLIST(r0, 0x8010640b, 0x0)

program did not crash
testing program (duration=44.259005206s, {Threaded:true 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}}): add_key$keyring-openat$comedi-ioctl$COMEDI_INSNLIST
detailed listing:
executing program 0:
add_key$keyring(&(0x7f0000000000), 0x0, 0x0, 0x0, 0xfffffffffffffffb)
r0 = openat$comedi(0xffffffffffffff9c, &(0x7f0000000040)='/dev/comedi4\x00', 0x181001, 0x0)
ioctl$COMEDI_INSNLIST(r0, 0x8010640b, 0x0)

program did not crash
testing program (duration=44.259005206s, {Threaded:true 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}}): add_key$keyring-openat$comedi-ioctl$COMEDI_INSNLIST
detailed listing:
executing program 0:
add_key$keyring(&(0x7f0000000000), 0x0, 0x0, 0x0, 0xfffffffffffffffb)
r0 = openat$comedi(0xffffffffffffff9c, &(0x7f0000000040)='/dev/comedi4\x00', 0x181001, 0x0)
ioctl$COMEDI_INSNLIST(r0, 0x8010640b, 0x0)

program did not crash
testing program (duration=44.259005206s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 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}}): add_key$keyring-openat$comedi-ioctl$COMEDI_INSNLIST
detailed listing:
executing program 0:
add_key$keyring(&(0x7f0000000000), 0x0, 0x0, 0x0, 0xfffffffffffffffb)
r0 = openat$comedi(0xffffffffffffff9c, &(0x7f0000000040)='/dev/comedi4\x00', 0x181001, 0x0)
ioctl$COMEDI_INSNLIST(r0, 0x8010640b, 0x0)

program did not crash
validation run: crashed=false
testing program (duration=44.259005206s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 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}}): add_key$keyring-openat$comedi-ioctl$COMEDI_INSNLIST
detailed listing:
executing program 0:
add_key$keyring(&(0x7f0000000000), 0x0, 0x0, 0x0, 0xfffffffffffffffb)
r0 = openat$comedi(0xffffffffffffff9c, &(0x7f0000000040)='/dev/comedi4\x00', 0x181001, 0x0)
ioctl$COMEDI_INSNLIST(r0, 0x8010640b, 0x0)

program crashed: WARNING: suspicious RCU usage in proc_sys_compare
validation run: crashed=true
testing program (duration=44.259005206s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 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}}): add_key$keyring-openat$comedi-ioctl$COMEDI_INSNLIST
detailed listing:
executing program 0:
add_key$keyring(&(0x7f0000000000), 0x0, 0x0, 0x0, 0xfffffffffffffffb)
r0 = openat$comedi(0xffffffffffffff9c, &(0x7f0000000040)='/dev/comedi4\x00', 0x181001, 0x0)
ioctl$COMEDI_INSNLIST(r0, 0x8010640b, 0x0)

program did not crash
validation run: crashed=false
testing program (duration=44.259005206s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 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}}): add_key$keyring-openat$comedi-ioctl$COMEDI_INSNLIST
detailed listing:
executing program 0:
add_key$keyring(&(0x7f0000000000), 0x0, 0x0, 0x0, 0xfffffffffffffffb)
r0 = openat$comedi(0xffffffffffffff9c, &(0x7f0000000040)='/dev/comedi4\x00', 0x181001, 0x0)
ioctl$COMEDI_INSNLIST(r0, 0x8010640b, 0x0)

program did not crash
validation run: crashed=false
testing program (duration=44.259005206s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 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}}): add_key$keyring-openat$comedi-ioctl$COMEDI_INSNLIST
detailed listing:
executing program 0:
add_key$keyring(&(0x7f0000000000), 0x0, 0x0, 0x0, 0xfffffffffffffffb)
r0 = openat$comedi(0xffffffffffffff9c, &(0x7f0000000040)='/dev/comedi4\x00', 0x181001, 0x0)
ioctl$COMEDI_INSNLIST(r0, 0x8010640b, 0x0)

program did not crash
validation run: crashed=false
testing program (duration=44.259005206s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 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}}): add_key$keyring-openat$comedi-ioctl$COMEDI_INSNLIST
detailed listing:
executing program 0:
add_key$keyring(&(0x7f0000000000), 0x0, 0x0, 0x0, 0xfffffffffffffffb)
r0 = openat$comedi(0xffffffffffffff9c, &(0x7f0000000040)='/dev/comedi4\x00', 0x181001, 0x0)
ioctl$COMEDI_INSNLIST(r0, 0x8010640b, 0x0)

program crashed: WARNING: suspicious RCU usage in proc_sys_compare
validation run: crashed=true
testing program (duration=44.259005206s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 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}}): add_key$keyring-openat$comedi-ioctl$COMEDI_INSNLIST
detailed listing:
executing program 0:
add_key$keyring(&(0x7f0000000000), 0x0, 0x0, 0x0, 0xfffffffffffffffb)
r0 = openat$comedi(0xffffffffffffff9c, &(0x7f0000000040)='/dev/comedi4\x00', 0x181001, 0x0)
ioctl$COMEDI_INSNLIST(r0, 0x8010640b, 0x0)

program did not crash
validation run: crashed=false
testing program (duration=44.259005206s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 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}}): add_key$keyring-openat$comedi-ioctl$COMEDI_INSNLIST
detailed listing:
executing program 0:
add_key$keyring(&(0x7f0000000000), 0x0, 0x0, 0x0, 0xfffffffffffffffb)
r0 = openat$comedi(0xffffffffffffff9c, &(0x7f0000000040)='/dev/comedi4\x00', 0x181001, 0x0)
ioctl$COMEDI_INSNLIST(r0, 0x8010640b, 0x0)

program crashed: WARNING: suspicious RCU usage in proc_sys_compare
validation run: crashed=true
reproducing took 26m23.363170348s
repro crashed as (corrupted=false):
=============================
WARNING: suspicious RCU usage
6.16.0-rc4-next-20250704-syzkaller #0 Not tainted
-----------------------------
fs/proc/proc_sysctl.c:934 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-executor/5875:
 #0: ffff88803582c428 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:557
 #1: ffff88802314c6e0 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:884 [inline]
 #1: ffff88802314c6e0 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: open_last_lookups fs/namei.c:3806 [inline]
 #1: ffff88802314c6e0 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: path_openat+0x8cb/0x3830 fs/namei.c:4043
 #2: ffff8880770f4b18 (&lockref->lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
 #2: ffff8880770f4b18 (&lockref->lock){+.+.}-{3:3}, at: d_wait_lookup fs/dcache.c:2537 [inline]
 #2: ffff8880770f4b18 (&lockref->lock){+.+.}-{3:3}, at: d_alloc_parallel+0xbe4/0x15e0 fs/dcache.c:2624

stack backtrace:
CPU: 1 UID: 0 PID: 5875 Comm: syz-executor Not tainted 6.16.0-rc4-next-20250704-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6871
 proc_sys_compare+0x27d/0x2c0 fs/proc/proc_sysctl.c:934
 d_same_name fs/dcache.c:2179 [inline]
 d_alloc_parallel+0x1060/0x15e0 fs/dcache.c:2637
 lookup_open fs/namei.c:3630 [inline]
 open_last_lookups fs/namei.c:3807 [inline]
 path_openat+0xa3b/0x3830 fs/namei.c:4043
 do_filp_open+0x1fa/0x410 fs/namei.c:4073
 do_sys_openat2+0x121/0x1c0 fs/open.c:1434
 do_sys_open fs/open.c:1449 [inline]
 __do_sys_openat fs/open.c:1465 [inline]
 __se_sys_openat fs/open.c:1460 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1460
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9b9098d211
Code: 75 57 89 f0 25 00 00 41 00 3d 00 00 41 00 74 49 80 3d 3a 93 1f 00 00 74 6d 89 da 48 89 ee bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 0f 87 93 00 00 00 48 8b 54 24 28 64 48 2b 14 25
RSP: 002b:00007ffe1e627790 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000080001 RCX: 00007f9b9098d211
RDX: 0000000000080001 RSI: 00007f9b90a2afe1 RDI: 00000000ffffff9c
RBP: 00007f9b90a2afe1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000009
R13: 00007ffe1e627830 R14: 0000000000000009 R15: 0000000000000000
 </TASK>

final repro crashed as (corrupted=false):
=============================
WARNING: suspicious RCU usage
6.16.0-rc4-next-20250704-syzkaller #0 Not tainted
-----------------------------
fs/proc/proc_sysctl.c:934 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-executor/5875:
 #0: ffff88803582c428 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:557
 #1: ffff88802314c6e0 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:884 [inline]
 #1: ffff88802314c6e0 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: open_last_lookups fs/namei.c:3806 [inline]
 #1: ffff88802314c6e0 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: path_openat+0x8cb/0x3830 fs/namei.c:4043
 #2: ffff8880770f4b18 (&lockref->lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
 #2: ffff8880770f4b18 (&lockref->lock){+.+.}-{3:3}, at: d_wait_lookup fs/dcache.c:2537 [inline]
 #2: ffff8880770f4b18 (&lockref->lock){+.+.}-{3:3}, at: d_alloc_parallel+0xbe4/0x15e0 fs/dcache.c:2624

stack backtrace:
CPU: 1 UID: 0 PID: 5875 Comm: syz-executor Not tainted 6.16.0-rc4-next-20250704-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6871
 proc_sys_compare+0x27d/0x2c0 fs/proc/proc_sysctl.c:934
 d_same_name fs/dcache.c:2179 [inline]
 d_alloc_parallel+0x1060/0x15e0 fs/dcache.c:2637
 lookup_open fs/namei.c:3630 [inline]
 open_last_lookups fs/namei.c:3807 [inline]
 path_openat+0xa3b/0x3830 fs/namei.c:4043
 do_filp_open+0x1fa/0x410 fs/namei.c:4073
 do_sys_openat2+0x121/0x1c0 fs/open.c:1434
 do_sys_open fs/open.c:1449 [inline]
 __do_sys_openat fs/open.c:1465 [inline]
 __se_sys_openat fs/open.c:1460 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1460
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9b9098d211
Code: 75 57 89 f0 25 00 00 41 00 3d 00 00 41 00 74 49 80 3d 3a 93 1f 00 00 74 6d 89 da 48 89 ee bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 0f 87 93 00 00 00 48 8b 54 24 28 64 48 2b 14 25
RSP: 002b:00007ffe1e627790 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000080001 RCX: 00007f9b9098d211
RDX: 0000000000080001 RSI: 00007f9b90a2afe1 RDI: 00000000ffffff9c
RBP: 00007f9b90a2afe1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000009
R13: 00007ffe1e627830 R14: 0000000000000009 R15: 0000000000000000
 </TASK>