Re: [syzbot] [ext4?] linux-next test error: general protection fault in __bh_submit

From: syzbot

Date: Sun Sep 06 2026 - 11:50:54 EST

Hello,

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

**
[ 1.781826][ T0] ** **
[ 1.785372][ T0] ** Use hash_pointers=always to force this mode off **
[ 1.788229][ T0] ** **
[ 1.791134][ T0] ** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **
[ 1.794147][ T0] **********************************************************
[ 1.800729][ T0] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=2, Nodes=2
[ 1.913042][ T0] allocated 167772160 bytes of page_ext
[ 1.915801][ T0] Node 0, zone DMA: page owner found early allocated 0 pages
[ 1.933467][ T0] Node 0, zone DMA32: page owner found early allocated 21251 pages
[ 1.941240][ T0] Node 0, zone Normal: page owner found early allocated 0 pages
[ 1.955796][ T0] Node 1, zone Normal: page owner found early allocated 19847 pages
[ 1.959586][ T0] Kernel/User page tables isolation: enabled
[ 1.963093][ T0] Dynamic Preempt: full
[ 1.967309][ T0] Running RCU self tests
[ 1.968917][ T0] Running RCU synchronous self tests
[ 1.971348][ T0] rcu: Preemptible hierarchical RCU implementation.
[ 1.973877][ T0] rcu: RCU lockdep checking is enabled.
[ 1.975705][ T0] rcu: RCU restricting CPUs from NR_CPUS=8 to nr_cpu_ids=2.
[ 1.979019][ T0] rcu: RCU callback double-/use-after-free debug is enabled.
[ 1.981744][ T0] rcu: RCU debug extended QS entry/exit.
[ 1.984219][ T0] All grace periods are expedited (rcu_expedited).
[ 1.987289][ T0] Trampoline variant of Tasks RCU enabled.
[ 1.989422][ T0] Tracing variant of Tasks RCU enabled.
[ 1.991680][ T0] rcu: RCU calculated value of scheduler-enlistment delay is 10 jiffies.
[ 1.995031][ T0] rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=2
[ 1.998432][ T0] Running RCU synchronous self tests
[ 2.000933][ T0] RCU Tasks: Setting shift to 1 and lim to 1 rcu_task_cb_adjust=1 rcu_task_cpu_ids=2.
[ 2.195362][ T0] NR_IRQS: 4352, nr_irqs: 440, preallocated irqs: 16
[ 2.198834][ T0] rcu: srcu_init: Setting srcu_struct sizes based on contention.
[ 2.201284][ T0] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[ 2.206079][ T0] kfence: initialized - using 2097152 bytes for 255 objects at 0xffff88823be00000-0xffff88823c000000
[ 2.211871][ T0] Console: colour VGA+ 80x25
[ 2.213842][ T0] printk: console [ttyS0] enabled
[ 2.213842][ T0] printk: console [ttyS0] enabled
[ 2.217871][ T0] printk: legacy bootconsole [earlyser0] disabled
[ 2.217871][ T0] printk: legacy bootconsole [earlyser0] disabled
[ 2.222615][ T0] Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar
[ 2.226003][ T0] ... MAX_LOCKDEP_SUBCLASSES: 8
[ 2.227931][ T0] ... MAX_LOCK_DEPTH: 48
[ 2.230174][ T0] ... MAX_LOCKDEP_KEYS: 8192
[ 2.232343][ T0] ... CLASSHASH_SIZE: 4096
[ 2.234359][ T0] ... MAX_LOCKDEP_ENTRIES: 1048576
[ 2.236604][ T0] ... MAX_LOCKDEP_CHAINS: 1048576
[ 2.239946][ T0] ... CHAINHASH_SIZE: 524288
[ 2.241944][ T0] memory used by lock dependency info: 106625 kB
[ 2.244550][ T0] memory used for stack traces: 8320 kB
[ 2.246632][ T0] per task-struct memory footprint: 1920 bytes
[ 2.250233][ T0] mempolicy: Enabling automatic NUMA balancing. Configure with numa_balancing= or the kernel.numa_balancing sysctl
[ 2.255922][ T0] ACPI: Core revision 20260408
[ 2.259621][ T0] APIC: Switch to symmetric I/O mode setup
[ 2.262474][ T0] x2apic enabled
[ 2.269220][ T0] APIC: Switched APIC routing to: physical x2apic
[ 2.283082][ T0] ..TIMER: vector=0x30 apic1=0 pin1=0 apic2=-1 pin2=-1
[ 2.286314][ T0] clocksource: tsc-early: mask: 0xffffffffffffffff max_cycles: 0x1fb63109b96, max_idle_ns: 440795265316 ns
[ 2.291274][ T0] Calibrating delay loop (skipped) preset value.. 4399.99 BogoMIPS (lpj=21999980)
[ 2.295562][ T0] Last level iTLB entries: 4KB 64, 2MB 8, 4MB 8
[ 2.298340][ T0] Last level dTLB entries: 4KB 64, 2MB 32, 4MB 32, 1GB 4
[ 2.301356][ T0] mitigations: Enabled attack vectors: user_kernel, user_user, guest_host, guest_guest, SMT mitigations: auto
[ 2.306450][ T0] Speculative Store Bypass: Mitigation: Speculative Store Bypass disabled via prctl
[ 2.311274][ T0] Spectre V2 : Mitigation: IBRS
[ 2.313098][ T0] RETBleed: Mitigation: IBRS
[ 2.314913][ T0] ITS: Mitigation: Aligned branch/return thunks
[ 2.317002][ T0] Spectre V2 : User space: Mitigation: STIBP via prctl
[ 2.319854][ T0] MDS: Mitigation: Clear CPU buffers
[ 2.321273][ T0] TAA: Mitigation: Clear CPU buffers
[ 2.323137][ T0] MMIO Stale Data: Vulnerable: Clear CPU buffers attempted, no microcode
[ 2.326988][ T0] Spectre V1 : Mitigation: usercopy/swapgs barriers and __user pointer sanitization
[ 2.331280][ T0] Spectre V2 : Spectre v2 / SpectreRSB: Filling RSB on context switch and VMEXIT
[ 2.335963][ T0] Spectre V2 : Enabling IBPB for BPF
[ 2.337974][ T0] Spectre V2 : mitigation: Enabling conditional Indirect Branch Prediction Barrier
[ 2.341320][ T0] active return thunk: its_return_thunk
[ 2.343502][ T0] Spectre V2 : Spectre BHI mitigation: SW BHB clearing on syscall and VM exit
[ 2.347384][ T0] x86/fpu: Supporting XSAVE feature 0x001: 'x87 floating point registers'
[ 2.351279][ T0] x86/fpu: Supporting XSAVE feature 0x002: 'SSE registers'
[ 2.353962][ T0] x86/fpu: Supporting XSAVE feature 0x004: 'AVX registers'
[ 2.356774][ T0] x86/fpu: xstate_offset[2]: 576, xstate_sizes[2]: 256
[ 2.359625][ T0] x86/fpu: Enabled xstate features 0x7, context size is 832 bytes, using 'standard' format.
[ 2.363542][ T0] ------------[ cut here ]------------
[ 2.365737][ T0] CPA detected W^X violation: 8000000000000023 -> 0000000000000023 range: 0xffffffffa0000000 - 0xffffffffa0000fff PFN 140600
[ 2.371284][ T0] WARNING: arch/x86/mm/pat/set_memory.c:725 at __change_page_attr_set_clr+0x1d69/0x2820, CPU#0: swapper/0/0
[ 2.376683][ T0] Modules linked in:
[ 2.378262][ T0] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full)
[ 2.381273][ T0] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
[ 2.385137][ T0] RIP: 0010:__change_page_attr_set_clr+0x1d79/0x2820
[ 2.388239][ T0] Code: 00 00 e8 ba 6c 4d 00 48 8b 4c 24 30 4c 8d 81 ff 0f 00 00 48 8d 3d 07 be 02 0f 48 8b b4 24 a0 00 00 00 4c 89 f2 4c 8b 4c 24 50 <67> 48 0f b9 3a e9 8d 00 00 00 e8 88 6c 4d 00 4c 89 f8 48 c1 e8 03
[ 2.391278][ T0] RSP: 0000:ffffffff8ea07820 EFLAGS: 00010293
[ 2.401293][ T0] RAX: ffffffff817a6b66 RBX: 8000000140600023 RCX: ffffffffa0000000
[ 2.404461][ T0] RDX: 0000000000000023 RSI: 8000000000000023 RDI: ffffffff907d2980
[ 2.407438][ T0] RBP: ffffffff8ea07ad0 R08: ffffffffa0000fff R09: 0000000000140600
[ 2.411273][ T0] R10: dffffc0000000000 R11: fffffbfff1d40ef4 R12: 8000000000000000
[ 2.414650][ T0] R13: 0000000000000002 R14: 0000000000000023 R15: 8000000000000002
[ 2.418017][ T0] FS: 0000000000000000(0000) GS:ffff888124cbf000(0000) knlGS:0000000000000000
[ 2.421275][ T0] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2.424161][ T0] CR2: ffff88823ffff000 CR3: 000000000eb48000 CR4: 00000000003506f0
[ 2.428084][ T0] Call Trace:
[ 2.429360][ T0] <TASK>
[ 2.431293][ T0] ? __pfx___mutex_unlock_slowpath+0x10/0x10
[ 2.434103][ T0] ? __purge_vmap_area_lazy+0x964/0xb40
[ 2.436630][ T0] ? __pfx___change_page_attr_set_clr+0x10/0x10
[ 2.439191][ T0] ? __might_resched+0x71/0x4c0
[ 2.441337][ T0] ? down_read+0x2b9/0x320
[ 2.443816][ T0] change_page_attr_set_clr+0x398/0x11d0
[ 2.447135][ T0] ? __pfx_change_page_attr_set_clr+0x10/0x10
[ 2.450043][ T0] ? trace_kmalloc+0x2a/0xf0
[ 2.451285][ T0] set_memory_x+0xd6/0x110
[ 2.453738][ T0] ? __pfx_set_memory_x+0x10/0x10
[ 2.456130][ T0] apply_retpolines+0x8e9/0x15a0
[ 2.459193][ T0] ? events_sysfs_show+0xdd/0xf0
[ 2.461280][ T0] ? __pfx_apply_retpolines+0x10/0x10
[ 2.464819][ T0] ? events_sysfs_show+0xdd/0xf0
[ 2.467699][ T0] ? events_sysfs_show+0xec/0xf0
[ 2.471274][ T0] ? events_sysfs_show+0xe3/0xf0
[ 2.473354][ T0] ? unregister_die_notifier+0x43/0x50
[ 2.475535][ T0] ? __pfx_int3_selftest+0x10/0x10
[ 2.477371][ T0] alternative_instructions+0x3a/0x100
[ 2.479281][ T0] arch_cpu_finalize_init+0xb2/0x1f0
[ 2.481279][ T0] start_kernel+0x310/0x3e0
[ 2.482865][ T0] x86_64_start_reservations+0x24/0x30
[ 2.485077][ T0] x86_64_start_kernel+0x137/0x1b0
[ 2.487088][ T0] common_startup_64+0x13e/0x157
[ 2.489518][ T0] </TASK>
[ 2.491278][ T0] Kernel panic - not syncing: kernel: panic_on_warn set ...
[ 2.494734][ T0] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full)
[ 2.499193][ T0] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
[ 2.501258][ T0] Call Trace:
[ 2.501258][ T0] <TASK>
[ 2.501258][ T0] vpanic+0x56d/0xa70
[ 2.501258][ T0] ? __pfx__printk+0x10/0x10
[ 2.501258][ T0] ? __pfx_vpanic+0x10/0x10
[ 2.501258][ T0] ? is_bpf_text_address+0x292/0x2b0
[ 2.501258][ T0] ? is_bpf_text_address+0x26/0x2b0
[ 2.501258][ T0] panic+0xc5/0xd0
[ 2.501258][ T0] ? __pfx_panic+0x10/0x10
[ 2.501258][ T0] ? common_startup_64+0x13e/0x157
[ 2.501258][ T0] __warn+0x315/0x4c0
[ 2.501258][ T0] ? __change_page_attr_set_clr+0x1d69/0x2820
[ 2.501258][ T0] ? __change_page_attr_set_clr+0x1d69/0x2820
[ 2.501258][ T0] __report_bug+0x276/0x570
[ 2.501258][ T0] ? __change_page_attr_set_clr+0x1d69/0x2820
[ 2.501258][ T0] ? __pfx___report_bug+0x10/0x10
[ 2.501258][ T0] report_bug_entry+0x19b/0x290
[ 2.501258][ T0] ? __change_page_attr_set_clr+0x1d79/0x2820
[ 2.501258][ T0] ? __change_page_attr_set_clr+0x1d7e/0x2820
[ 2.501258][ T0] handle_bug+0xce/0x200
[ 2.501258][ T0] exc_invalid_op+0x1a/0x50
[ 2.501258][ T0] asm_exc_invalid_op+0x1a/0x20
[ 2.501258][ T0] RIP: 0010:__change_page_attr_set_clr+0x1d79/0x2820
[ 2.501258][ T0] Code: 00 00 e8 ba 6c 4d 00 48 8b 4c 24 30 4c 8d 81 ff 0f 00 00 48 8d 3d 07 be 02 0f 48 8b b4 24 a0 00 00 00 4c 89 f2 4c 8b 4c 24 50 <67> 48 0f b9 3a e9 8d 00 00 00 e8 88 6c 4d 00 4c 89 f8 48 c1 e8 03
[ 2.501258][ T0] RSP: 0000:ffffffff8ea07820 EFLAGS: 00010293
[ 2.501258][ T0] RAX: ffffffff817a6b66 RBX: 8000000140600023 RCX: ffffffffa0000000
[ 2.501258][ T0] RDX: 0000000000000023 RSI: 8000000000000023 RDI: ffffffff907d2980
[ 2.501258][ T0] RBP: ffffffff8ea07ad0 R08: ffffffffa0000fff R09: 0000000000140600
[ 2.501258][ T0] R10: dffffc0000000000 R11: fffffbfff1d40ef4 R12: 8000000000000000
[ 2.501258][ T0] R13: 0000000000000002 R14: 0000000000000023 R15: 8000000000000002
[ 2.501258][ T0] ? __change_page_attr_set_clr+0x1d56/0x2820
[ 2.501258][ T0] ? __pfx___mutex_unlock_slowpath+0x10/0x10
[ 2.501258][ T0] ? __purge_vmap_area_lazy+0x964/0xb40
[ 2.501258][ T0] ? __pfx___change_page_attr_set_clr+0x10/0x10
[ 2.501258][ T0] ? __might_resched+0x71/0x4c0
[ 2.501258][ T0] ? down_read+0x2b9/0x320
[ 2.501258][ T0] change_page_attr_set_clr+0x398/0x11d0
[ 2.501258][ T0] ? __pfx_change_page_attr_set_clr+0x10/0x10
[ 2.501258][ T0] ? trace_kmalloc+0x2a/0xf0
[ 2.501258][ T0] set_memory_x+0xd6/0x110
[ 2.501258][ T0] ? __pfx_set_memory_x+0x10/0x10
[ 2.501258][ T0] apply_retpolines+0x8e9/0x15a0
[ 2.501258][ T0] ? events_sysfs_show+0xdd/0xf0
[ 2.501258][ T0] ? __pfx_apply_retpolines+0x10/0x10
[ 2.501258][ T0] ? events_sysfs_show+0xdd/0xf0
[ 2.501258][ T0] ? events_sysfs_show+0xec/0xf0
[ 2.501258][ T0] ? events_sysfs_show+0xe3/0xf0
[ 2.501258][ T0] ? unregister_die_notifier+0x43/0x50
[ 2.501258][ T0] ? __pfx_int3_selftest+0x10/0x10
[ 2.501258][ T0] alternative_instructions+0x3a/0x100
[ 2.501258][ T0] arch_cpu_finalize_init+0xb2/0x1f0
[ 2.501258][ T0] start_kernel+0x310/0x3e0
[ 2.501258][ T0] x86_64_start_reservations+0x24/0x30
[ 2.501258][ T0] x86_64_start_kernel+0x137/0x1b0
[ 2.501258][ T0] common_startup_64+0x13e/0x157
[ 2.501258][ T0] </TASK>
[ 2.501258][ T0] 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-build185907891=/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 85995287a88
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=85995287a888340d8818a8f3c43e2e89555eea21 -X github.com/google/syzkaller/prog.gitRevisionDate=20260902-115702" ./sys/syz-sysgen | grep -q false || go install -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=85995287a888340d8818a8f3c43e2e89555eea21 -X github.com/google/syzkaller/prog.gitRevisionDate=20260902-115702" ./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=85995287a888340d8818a8f3c43e2e89555eea21 -X github.com/google/syzkaller/prog.gitRevisionDate=20260902-115702" -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=\"85995287a888340d8818a8f3c43e2e89555eea21\"
/usr/bin/ld: /tmp/cc6c4SOQ.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=138aecf9580000

Tested on:

commit: af5f1280 Add linux-next specific files for 20260904
git tree: linux-next
kernel config: https://syzkaller.appspot.com/x/.config?x=bb4a32c282cc2ec7
dashboard link: https://syzkaller.appspot.com/bug?extid=5a7a23af225c215902e7
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=17fd5125580000