syzbot


BUG: soft lockup in pipe_read

Status: upstream: reported syz repro on 2024/01/25 02:05
Subsystems: fs mm
[Documentation on labels]
Reported-by: syzbot+8b31216d2ea3f2c6905b@syzkaller.appspotmail.com
First crash: 862d, last: 481d
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
30be771c-9661-4c2b-9867-eabfacf224b1 assessment-security 💥 BUG: soft lockup in pipe_read 2026/05/26 12:48 2026/05/26 12:48 2026/05/26 13:06 c69befb30ac10e158cc9d1557b508ee3f0eca1de failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/ddc9086063c9b51b1c367e3c22e2db6de23a5260" "-s" "bzImage" "compile_commands.json"]: exit status 2 Root cause: ld.lld: error: undefined symbol: wcslen * * Restart config... * * * General setup * Compile also drivers which will not load (COMPILE_TEST) [N/y/?] n Compile the kernel with warnings as errors (WERROR) [N/y/?] n Local version - append to kernel release (LOCALVERSION) [] Automatically append version information to the version string (LOCALVERSION_AUTO) [Y/n/?] y Build ID Salt (BUILD_SALT) [] Kernel compression mode > 1. Gzip (KERNEL_GZIP) (NEW) 2. Bzip2 (KERNEL_BZIP2) (NEW) 3. LZMA (KERNEL_LZMA) (NEW) 4. XZ (KERNEL_XZ) (NEW) 5. LZO (KERNEL_LZO) (NEW) 6. LZ4 (KERNEL_LZ4) (NEW) 7. ZSTD (KERNEL_ZSTD) (NEW) choice[1-7?]: Error in reading or end of file. Default init path (DEFAULT_INIT) [] Default hostname (DEFAULT_HOSTNAME) [(none)] (none) System V IPC (SYSVIPC) [Y/n/?] y POSIX Message Queues (POSIX_MQUEUE) [Y/n/?] y General notification queue (WATCH_QUEUE) [Y/n/?] y Enable process_vm_readv/writev syscalls (CROSS_MEMORY_ATTACH) [Y/n/?] y uselib syscall (for libc5 and earlier) (USELIB) [N/y/?] n Auditing support (AUDIT) [Y/n/?] y * * Timers subsystem * Timer tick handling 1. Periodic timer ticks (constant rate, no dynticks) (HZ_PERIODIC) > 2. Idle dynticks system (tickless idle) (NO_HZ_IDLE) 3. Full dynticks system (tickless) (NO_HZ_FULL) choice[1-3?]: 2 Force user context tracking (CONTEXT_TRACKING_USER_FORCE) [N/y/?] n Old Idle dynticks config (NO_HZ) [Y/n/?] y High Resolution Timer Support (HIGH_RES_TIMERS) [Y/n/?] y Clocksource watchdog maximum allowable skew (in microseconds) (CLOCKSOURCE_WATCHDOG_MAX_SKEW_US) [125] (NEW) Error in reading or end of file. Preemption Model 1. No Forced Preemption (Server) (PREEMPT_NONE) 2. Voluntary Kernel Preemption (Desktop) (PREEMPT_VOLUNTARY) > 3. Preemptible Kernel (Low-Latency Desktop) (PREEMPT) 4. Scheduler controlled preemption model (PREEMPT_LAZY) (NEW) choice[1-4?]: Error in reading or end of file. Fully Preemptible Kernel (Real-Time) (PREEMPT_RT) [N/y/?] n Preemption behaviour defined on boot (PREEMPT_DYNAMIC) [N/y/?] n Core Scheduling for SMT (SCHED_CORE) [N/y/?] n CPU isolation (CPU_ISOLATION) [Y/n/?] y Kernel .config support (IKCONFIG) [Y/n/m/?] y Enable access to .config through /proc/config.gz (IKCONFIG_PROC) [Y/n/?] y Enable kernel headers through /sys/kernel/kheaders.tar.xz (IKHEADERS) [N/m/y/?] n Kernel log buffer size (16 => 64KB, 17 => 128KB) (LOG_BUF_SHIFT) [18] 18 CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB) (LOG_CPU_MAX_BUF_SHIFT) [12] 12 Printk indexing debugfs interface (PRINTK_INDEX) [N/y/?] n Memory placement aware NUMA scheduler (NUMA_BALANCING) [Y/n/?] y Automatically enable NUMA aware memory/task placement (NUMA_BALANCING_DEFAULT_ENABLED) [Y/n/?] y Checkpoint/restore support (CHECKPOINT_RESTORE) [Y/n/?] y Automatic process group scheduling (SCHED_AUTOGROUP) [Y/n/?] y Kernel->user space relay support (formerly relayfs) (RELAY) [Y/?] y Initial RAM filesystem and RAM disk (initramfs/initrd) support (BLK_DEV_INITRD) [Y/n/?] y Initramfs source file(s) (INITRAMFS_SOURCE) [] Support initial ramdisk/ramfs compressed using gzip (RD_GZIP) [Y/n/?] y Support initial ramdisk/ramfs compressed using bzip2 (RD_BZIP2) [Y/n/?] y Support initial ramdisk/ramfs compressed using LZMA (RD_LZMA) [Y/n/?] y Support initial ramdisk/ramfs compressed using XZ (RD_XZ) [Y/n/?] y Support initial ramdisk/ramfs compressed using LZO (RD_LZO) [Y/n/?] y Support initial ramdisk/ramfs compressed using LZ4 (RD_LZ4) [Y/n/?] y Support initial ramdisk/ramfs compressed using ZSTD (RD_ZSTD) [Y/n/?] y Boot config support (BOOT_CONFIG) [N/y/?] n Preserve cpio archive mtimes in initramfs (INITRAMFS_PRESERVE_MTIME) [Y/n/?] y Compiler optimization level > 1. Optimize for performance (-O2) (CC_OPTIMIZE_FOR_PERFORMANCE) 2. Optimize for size (-Os) (CC_OP
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [fs?] BUG: soft lockup in pipe_read 0 (1) 2024/01/25 02:05
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in pipe_read (2) kasan mm 1 1 1448d 1448d 0/29 auto-closed as invalid on 2022/09/12 02:39
upstream INFO: rcu detected stall in pipe_read mm 1 6 2336d 2372d 0/29 closed as dup on 2019/12/03 08:34
Last patch testing requests (10)
Created Duration User Patch Repo Result
2026/05/31 06:10 55m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log
2026/04/17 01:57 3h49m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci error
2026/03/21 19:19 26m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci error
2026/02/05 17:10 28m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci error
2026/01/10 15:25 43m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log
2025/11/27 14:55 1h43m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log
2025/11/01 06:55 1h27m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log
2025/09/18 11:15 21m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log
2025/08/23 00:59 27m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log
2025/07/10 07:57 22m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log

Sample crash report:
watchdog: BUG: soft lockup - CPU#0 stuck for 21s! [syz-executor:6638]
Modules linked in:
irq event stamp: 4860
hardirqs last  enabled at (4859): [<ffff80008b8294d8>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]
hardirqs last  enabled at (4859): [<ffff80008b8294d8>] _raw_spin_unlock_irqrestore+0x38/0x98 kernel/locking/spinlock.c:194
hardirqs last disabled at (4860): [<ffff80008b8056d0>] __el1_irq arch/arm64/kernel/entry-common.c:557 [inline]
hardirqs last disabled at (4860): [<ffff80008b8056d0>] el1_interrupt+0x24/0x68 arch/arm64/kernel/entry-common.c:575
softirqs last  enabled at (4700): [<ffff800080129934>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32
softirqs last disabled at (4698): [<ffff800080129900>] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19
CPU: 0 UID: 0 PID: 6638 Comm: syz-executor Not tainted 6.14.0-rc1-syzkaller-g2014c95afece #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __pi_memset_generic+0x78/0x188 arch/arm64/lib/memset.S:96
lr : __asan_memset+0x48/0x64 mm/kasan/shadow.c:87
sp : ffff8000a9f47690
x29: ffff8000a9f47690 x28: ffff0000d6982959 x27: 0000000000000000
x26: dfff800000000000 x25: 1fffe0001ad30526 x24: ffff0000d6982930
x23: 1fffe0001ad30529 x22: dfff800000000000 x21: ffff8000a9f477d0
x20: 0000000000000000 x19: 0000000000000010 x18: 0000000000000000
x17: 0000000000000000 x16: ffff80008b769d48 x15: 0000000000000002
x14: 1ffff000153e8efa x13: 0000000000000000 x12: 0000000000000000
x11: ffff7000153e8efc x10: 1ffff000153e8efb x9 : dfff800000000000
x8 : ffff8000a9f477d0 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000010
x2 : 0000000000000010 x1 : 0000000000000000 x0 : ffff8000a9f477d0
Call trace:
 __pi_memset_generic+0x78/0x188 arch/arm64/lib/memset.S:95 (P)
 __schedule+0xb8/0x257c kernel/sched/core.c:6654
 __schedule_loop kernel/sched/core.c:6841 [inline]
 schedule+0xbc/0x238 kernel/sched/core.c:6856
 pipe_read+0x9e4/0xee0 fs/pipe.c:391
 new_sync_read fs/read_write.c:484 [inline]
 vfs_read+0x698/0x974 fs/read_write.c:565
 ksys_read+0x15c/0x26c fs/read_write.c:708
 __do_sys_read fs/read_write.c:717 [inline]
 __se_sys_read fs/read_write.c:715 [inline]
 __arm64_sys_read+0x7c/0x90 fs/read_write.c:715
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 6.14.0-rc1-syzkaller-g2014c95afece #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : arch_local_irq_enable+0x8/0xc arch/arm64/include/asm/irqflags.h:50
lr : default_idle_call+0xf8/0x128 kernel/sched/idle.c:124
sp : ffff800097dc7d10
x29: ffff800097dc7d10 x28: dfff800000000000 x27: 1ffff00012fb8fb0
x26: ffff80008fbcd000 x25: 0000000000000000 x24: 0000000000000002
x23: 1ffff00011f79ac0 x22: ffff80008fbcd600 x21: 0000000000000000
x20: ffff0000c1b88000 x19: ffff800080410fc8 x18: 1fffe000366f6486
x17: ffff80008fbcd000 x16: ffff8000804108a8 x15: 0000000000000001
x14: 1fffe000366f812f x13: 0000000000000000 x12: 0000000000000003
x11: 0000000000000001 x10: 0000000000000003 x9 : 0000000000000000
x8 : 00000000000581fd x7 : ffff8000805c3da8 x6 : 0000000000000000
x5 : 0000000000000001 x4 : 0000000000000001 x3 : ffff80008b809fe0
x2 : 0000000000000000 x1 : ffff80008b8ba180 x0 : ffff800123c9a000
Call trace:
 __daif_local_irq_enable arch/arm64/include/asm/irqflags.h:26 [inline] (P)
 arch_local_irq_enable+0x8/0xc arch/arm64/include/asm/irqflags.h:48 (P)
 cpuidle_idle_call kernel/sched/idle.c:185 [inline]
 do_idle+0x1ec/0x4e0 kernel/sched/idle.c:325
 cpu_startup_entry+0x5c/0x74 kernel/sched/idle.c:423
 secondary_start_kernel+0x1bc/0x1e4 arch/arm64/kernel/smp.c:279
 __secondary_switched+0xc0/0xc4 arch/arm64/kernel/head.S:417

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/02/05 11:06 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 2014c95afece 5896748e .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 BUG: soft lockup in pipe_read
2024/01/21 01:56 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 0802e17d9aca 9bd8dcda .config console log report syz [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 BUG: soft lockup in pipe_read
2024/06/13 02:09 linux-next a957267fa7e9 2aa5052f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: rcu detected stall in pipe_read
2024/05/29 03:32 linux-next 6dc544b66971 34889ee3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: rcu detected stall in pipe_read
2024/05/29 03:28 linux-next 6dc544b66971 34889ee3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: rcu detected stall in pipe_read
* Struck through repros no longer work on HEAD.