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charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: feacb1774bd5 Merge tag 'sched_ext-for-6.16' of git://git.k.. git tree: upstream console+strace: https://syzkaller.appspot.com/x/log.txt?x=1410dbf4580000 kernel config: https://syzkaller.appspot.com/x/.config?x=ded97a85afe9a6c8 dashboard link: https://syzkaller.appspot.com/bug?extid=818ea33e64f8caf968d1 compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16d5fbf4580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11d5fbf4580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/927d3353c6ef/disk-feacb177.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/00070c1b5ee0/vmlinux-feacb177.xz kernel image: https://storage.googleapis.com/syzbot-assets/d7e700ecb777/bzImage-feacb177.xz The issue was bisected to: commit b3a4dbc89d4021b3f90ff6a13537111a004f9d07 Author: Gabriel Krisman Bertazi Date: Thu Oct 5 00:05:31 2023 +0000 io_uring/kbuf: Use slab for struct io_buffer objects bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=169feed4580000 final oops: https://syzkaller.appspot.com/x/report.txt?x=159feed4580000 console output: https://syzkaller.appspot.com/x/log.txt?x=119feed4580000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+818ea33e64f8caf968d1@syzkaller.appspotmail.com Fixes: b3a4dbc89d40 ("io_uring/kbuf: Use slab for struct io_buffer objects") INFO: task syz-executor266:5869 blocked for more than 143 seconds. Not tainted 6.15.0-syzkaller-03589-gfeacb1774bd5 #0 Blocked by coredump. "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor266 state:D stack:26952 pid:5869 tgid:5863 ppid:5860 task_flags:0x400548 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5392 [inline] __schedule+0x16f5/0x4d00 kernel/sched/core.c:6781 __schedule_loop kernel/sched/core.c:6859 [inline] schedule+0x165/0x360 kernel/sched/core.c:6874 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6931 __mutex_lock_common kernel/locking/mutex.c:678 [inline] __mutex_lock+0x724/0xe80 kernel/locking/mutex.c:746 io_uring_del_tctx_node+0xf0/0x2c0 io_uring/tctx.c:179 io_uring_clean_tctx+0xd4/0x1a0 io_uring/tctx.c:195 io_uring_cancel_generic+0x68f/0x730 io_uring/io_uring.c:3204 io_uring_files_cancel include/linux/io_uring.h:19 [inline] do_exit+0x56a/0x2550 kernel/exit.c:915 do_group_exit+0x21c/0x2d0 kernel/exit.c:1108 get_signal+0x125e/0x1310 kernel/signal.c:3034 arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop+0x75/0x110 kernel/entry/common.c:111 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline] do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff7ab3f0599 RSP: 002b:00007ff7ab3a9218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007ff7ab47a328 RCX: 00007ff7ab3f0599 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007ff7ab47a328 RBP: 00007ff7ab47a320 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003 R13: 00002000000000c0 R14: 0000200000000340 R15: 0000200000000980 Showing all locks held in the system: 5 locks held by kworker/u8:1/13: #0: ffff8880b8739f58 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:606 #1: ffff8880b8723f08 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x39e/0x6d0 kernel/sched/psi.c:987 #2: ffff8880b8725958 (&base->lock){-.-.}-{2:2}, at: __mod_timer+0x8ee/0xf30 kernel/time/timer.c:1117 #3: ffffffff99cfa278 (&obj_hash[i].lock){-.-.}-{2:2}, at: debug_object_activate+0xbb/0x420 lib/debugobjects.c:818 #4: ffffffff8dfe8928 (text_mutex){+.+.}-{4:4}, at: arch_jump_label_transform_apply+0x17/0x30 arch/x86/kernel/jump_label.c:145 1 lock held by khungtaskd/31: #0: ffffffff8e13ccc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8e13ccc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #0: ffffffff8e13ccc0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6770 2 locks held by getty/5589: #0: ffff888030bef0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc90002fee2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222 1 lock held by syz-executor266/5865: 1 lock held by syz-executor266/5866: 2 locks held by syz-executor266/5867: 1 lock held by syz-executor266/5869: #0: ffff8880781600a8 (&ctx->uring_lock){+.+.}-{4:4}, at: io_uring_del_tctx_node+0xf0/0x2c0 io_uring/tctx.c:179 2 locks held by syz-executor266/5870: 2 locks held by syz-executor266/5868: ============================================= NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.15.0-syzkaller-03589-gfeacb1774bd5 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:274 [inline] watchdog+0xfee/0x1030 kernel/hung_task.c:437 kthread+0x70e/0x8a0 kernel/kthread.c:464 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 5868 Comm: syz-executor266 Not tainted 6.15.0-syzkaller-03589-gfeacb1774bd5 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:32 [inline] RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:109 [inline] RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:127 [inline] RIP: 0010:lock_release+0xaa/0x3e0 kernel/locking/lockdep.c:5888 Code: 92 41 83 bf ec 0a 00 00 00 0f 85 1e 02 00 00 49 81 3e 80 f3 5c 93 0f 84 11 02 00 00 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 <48> 8b 5c 24 20 fa 48 c7 c7 0e 10 97 8d e8 94 56 c0 09 65 ff 05 8d RSP: 0018:ffffc900045ef3f0 EFLAGS: 00000202 RAX: 0000000000000000 RBX: 00007ff7ab47a301 RCX: 2c8b038b74fda600 RDX: ffffffff9025c800 RSI: ffffffff8be24de0 RDI: ffffffff8be24da0 RBP: dffffc0000000000 R08: 0000000000000022 R09: ffffffff81724865 R10: ffffc900045ef578 R11: ffffffff81ac98f0 R12: 00007ff7ab3a9208 R13: ffffffff81724865 R14: ffffffff8e13ccc0 R15: ffff888077b2da00 FS: 00007ff7ab3a96c0(0000) GS:ffff888125c8c000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fd695af76c8 CR3: 000000007fa2e000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_lock_release include/linux/rcupdate.h:341 [inline] rcu_read_unlock include/linux/rcupdate.h:871 [inline] class_rcu_destructor include/linux/rcupdate.h:1155 [inline] unwind_next_frame+0x19a9/0x2390 arch/x86/kernel/unwind_orc.c:680 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:377 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394 kasan_kmalloc include/linux/kasan.h:260 [inline] __kmalloc_cache_noprof+0x230/0x3d0 mm/slub.c:4358 kmalloc_noprof include/linux/slab.h:905 [inline] io_add_buffers io_uring/kbuf.c:497 [inline] __io_manage_buffers_legacy io_uring/kbuf.c:538 [inline] io_manage_buffers_legacy+0x334/0xc90 io_uring/kbuf.c:551 __io_issue_sqe+0x17e/0x4b0 io_uring/io_uring.c:1730 io_issue_sqe+0x165/0xfd0 io_uring/io_uring.c:1753 io_queue_sqe io_uring/io_uring.c:1960 [inline] io_submit_sqe io_uring/io_uring.c:2216 [inline] io_submit_sqes+0xa38/0x1c50 io_uring/io_uring.c:2329 __do_sys_io_uring_enter io_uring/io_uring.c:3396 [inline] __se_sys_io_uring_enter+0x2df/0x2b20 io_uring/io_uring.c:3330 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: 0033:0x7ff7ab3f0599 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 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 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ff7ab3a9208 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa RAX: ffffffffffffffda RBX: 00007ff7ab47a328 RCX: 00007ff7ab3f0599 RDX: 00000000000000f0 RSI: 0000000000003516 RDI: 0000000000000003 RBP: 00007ff7ab47a320 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003 R13: 00002000000000c0 R14: 0000200000000340 R15: 0000200000000980 INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.349 msecs --- This report is generated by a bot. 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