On Fri, Sep 27, 2024 at 4:57 PM syzbot <[email protected]> wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: 075dbe9f6e3c Merge tag 'soc-ep93xx-dt-6.12' of git://git.k.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=15f07a80580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=86254f9e0a8f2c98 > dashboard link: https://syzkaller.appspot.com/bug?extid=0ec1e96c2cdf5c0e512a > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) > 2.40 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: > https://storage.googleapis.com/syzbot-assets/1be80941df60/disk-075dbe9f.raw.xz > vmlinux: > https://storage.googleapis.com/syzbot-assets/494a9ac89c09/vmlinux-075dbe9f.xz > kernel image: > https://storage.googleapis.com/syzbot-assets/919788d8c731/bzImage-075dbe9f.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: [email protected] > > audit: type=1400 audit(6022412112.141:243086): avc: denied { read } for > pid=2950 comm="syslogd" name="log" dev="sda1" ino=1915 > scontext=system_u:system_r:syslogd_t tcontext=system_u:object_r:var_t > tclass=lnk_file permissive=0 > audit: type=1400 audit(6022412112.181:243087): avc: denied { read } for > pid=2950 comm="syslogd" name="log" dev="sda1" ino=1915 > scontext=system_u:system_r:syslogd_t tcontext=system_u:object_r:var_t > tclass=lnk_file permissive=0 > ================================================================== > BUG: KCSAN: assert: race in __block_task kernel/sched/sched.h:2770 [inline] > BUG: KCSAN: assert: race in dequeue_entities+0x6df/0x760 > kernel/sched/fair.c:7177 > > race at unknown origin, with assert no writes to 0xffff888101764268 of 4 > bytes by task 29 on cpu 1: > __block_task kernel/sched/sched.h:2770 [inline] > dequeue_entities+0x6df/0x760 kernel/sched/fair.c:7177 > pick_next_entity kernel/sched/fair.c:5627 [inline] > pick_task_fair kernel/sched/fair.c:8856 [inline] > pick_next_task_fair+0x7d/0x410 kernel/sched/fair.c:8876 > __pick_next_task kernel/sched/core.c:5955 [inline] > pick_next_task kernel/sched/core.c:6477 [inline] > __schedule+0x284/0x940 kernel/sched/core.c:6629 > __schedule_loop kernel/sched/core.c:6752 [inline] > schedule+0x55/0xc0 kernel/sched/core.c:6767 > kauditd_thread+0x56b/0x650 kernel/audit.c:911 > kthread+0x1d1/0x210 kernel/kthread.c:389 > ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > > value changed: 0x00000000 -> 0x00000001 > > Reported by Kernel Concurrency Sanitizer on: > CPU: 1 UID: 0 PID: 29 Comm: kauditd Not tainted > 6.11.0-syzkaller-11558-g075dbe9f6e3c #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 09/13/2024 > ==================================================================
+PeterZ, who added the KCSAN assertion. Peter, I am also hitting the same assert on ARM while fuzzing KVM. It is tricky to reproduce though (we probably need to stress the scheduler hard enough): ================================================================== BUG: KCSAN: assert: race in dequeue_entities+0x6d8/0x794 kernel/sched/sched.h:2773 race at unknown origin, with assert no writes to 0xffffff80039f91e8 of 4 bytes by task 27858 on cpu 2: dequeue_entities+0x6d8/0x794 kernel/sched/sched.h:2773 pick_next_task_fair+0x84/0x394 kernel/sched/fair.c:5627 __schedule+0x218/0x888 kernel/sched/core.c:5968 preempt_schedule_irq+0x3c/0x68 kernel/sched/core.c:7012 arm64_preempt_schedule_irq+0x2c/0x40 arch/arm64/kernel/entry-common.c:301 __el1_irq arch/arm64/kernel/entry-common.c:539 [inline] el1_interrupt+0x3c/0x54 arch/arm64/kernel/entry-common.c:551 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:556 el1h_64_irq+0x64/0x68 arch/arm64/kernel/entry.S:594 flush_ptrace_hw_breakpoint+0x4f8/0x6b0 arch/arm64/kernel/ptrace.c:221 flush_thread+0x70/0xf4 arch/arm64/kernel/process.c:287 begin_new_exec+0x9ac/0xcdc fs/exec.c:1307 load_elf_binary+0x4d0/0x1330 fs/binfmt_elf.c:996 bprm_execve+0x3d8/0x958 fs/exec.c:1752 kernel_execve+0x550/0x57c fs/exec.c:2012 call_usermodehelper_exec_async+0x18c/0x270 kernel/umh.c:110 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860 value changed: 0x00000000 -> 0x00000001 Reported by Kernel Concurrency Sanitizer on: CPU: 2 UID: 0 PID: 27858 Comm: kworker/u16:3 Not tainted 6.12.0-rc4-00001-g517096192323-dirty #84 Hardware name: linux,dummy-virt (DT) ==================================================================
