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e9e14a558f8ab-3d7ec26b6f6mr34774065ab.17.1744392365089; Fri, 11 Apr 2025 10:26:05 -0700 (PDT) Date: Fri, 11 Apr 2025 10:26:05 -0700 In-Reply-To: <0000000000004aa700061379547e@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <67f950ad.050a0220.2c5fcf.0004.GAE@google.com> Subject: Re: [syzbot] Re: [syzbot] [bpf?] possible deadlock in __bpf_ringbuf_reserve From: syzbot To: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" For archival purposes, forwarding an incoming command email to linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com. *** Subject: Re: [syzbot] [bpf?] possible deadlock in __bpf_ringbuf_reserve Author: memxor@gmail.com On Fri, 11 Apr 2025 at 19:19, syzbot wrote: > > Hello, > > syzbot has tested the proposed patch but the reproducer is still triggering an issue: > possible deadlock in __bpf_ringbuf_reserve > > ============================================ > WARNING: possible recursive locking detected > 6.15.0-rc1-syzkaller-ge618ee89561b #0 Not tainted > -------------------------------------------- > kworker/2:3/6044 is trying to acquire lock: > ffffc90006f360d8 (&rb->spinlock){-.-.}-{2:2}, at: __bpf_ringbuf_reserve+0x36e/0x4b0 kernel/bpf/ringbuf.c:423 > > but task is already holding lock: > ffffc900070410d8 (&rb->spinlock){-.-.}-{2:2}, at: __bpf_ringbuf_reserve+0x36e/0x4b0 kernel/bpf/ringbuf.c:423 > > other info that might help us debug this: > Possible unsafe locking scenario: > > CPU0 > ---- > lock(&rb->spinlock); > lock(&rb->spinlock); > > *** DEADLOCK *** > > May be due to missing lock nesting notation > > 6 locks held by kworker/2:3/6044: > #0: ffff88801b48ad48 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3213 > #1: ffffc90004c1fd18 ((work_completion)(&(&ssp->srcu_sup->work)->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3214 > #2: ffff88801ea8f158 (&ssp->srcu_sup->srcu_gp_mutex){+.+.}-{4:4}, at: srcu_advance_state kernel/rcu/srcutree.c:1701 [inline] > #2: ffff88801ea8f158 (&ssp->srcu_sup->srcu_gp_mutex){+.+.}-{4:4}, at: process_srcu+0x73/0x1920 kernel/rcu/srcutree.c:1861 > #3: ffffffff8e3c15c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] > #3: ffffffff8e3c15c0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] > #3: ffffffff8e3c15c0 (rcu_read_lock){....}-{1:3}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2362 [inline] > #3: ffffffff8e3c15c0 (rcu_read_lock){....}-{1:3}, at: bpf_trace_run2+0x1b6/0x590 kernel/trace/bpf_trace.c:2404 > #4: ffffc900070410d8 (&rb->spinlock){-.-.}-{2:2}, at: __bpf_ringbuf_reserve+0x36e/0x4b0 kernel/bpf/ringbuf.c:423 > #5: ffffffff8e3c15c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] > #5: ffffffff8e3c15c0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] > #5: ffffffff8e3c15c0 (rcu_read_lock){....}-{1:3}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2362 [inline] > #5: ffffffff8e3c15c0 (rcu_read_lock){....}-{1:3}, at: bpf_trace_run2+0x1b6/0x590 kernel/trace/bpf_trace.c:2404 > > stack backtrace: > CPU: 2 UID: 0 PID: 6044 Comm: kworker/2:3 Not tainted 6.15.0-rc1-syzkaller-ge618ee89561b #0 PREEMPT(full) > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 > Workqueue: rcu_gp process_srcu > Call Trace: > > __dump_stack lib/dump_stack.c:94 [inline] > dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 > print_deadlock_bug+0x1e9/0x240 kernel/locking/lockdep.c:3042 > check_deadlock kernel/locking/lockdep.c:3094 [inline] > validate_chain kernel/locking/lockdep.c:3896 [inline] > __lock_acquire+0xff7/0x1ba0 kernel/locking/lockdep.c:5235 > lock_acquire kernel/locking/lockdep.c:5866 [inline] > lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 > __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] > _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162 > __bpf_ringbuf_reserve+0x36e/0x4b0 kernel/bpf/ringbuf.c:423 > ____bpf_ringbuf_reserve kernel/bpf/ringbuf.c:474 [inline] > bpf_ringbuf_reserve+0x57/0x90 kernel/bpf/ringbuf.c:466 > bpf_prog_385141c453c15099+0x36/0x5d > bpf_dispatcher_nop_func include/linux/bpf.h:1316 [inline] > __bpf_prog_run include/linux/filter.h:718 [inline] > bpf_prog_run include/linux/filter.h:725 [inline] > __bpf_trace_run kernel/trace/bpf_trace.c:2363 [inline] > bpf_trace_run2+0x230/0x590 kernel/trace/bpf_trace.c:2404 > __bpf_trace_contention_begin+0xc9/0x110 include/trace/events/lock.h:95 > __traceiter_contention_begin+0x5a/0xa0 include/trace/events/lock.h:95 > __preempt_count_dec_and_test arch/x86/include/asm/preempt.h:95 [inline] > class_preempt_notrace_destructor include/linux/preempt.h:482 [inline] > __do_trace_contention_begin include/trace/events/lock.h:95 [inline] > trace_contention_begin.constprop.0+0xde/0x160 include/trace/events/lock.h:95 > __pv_queued_spin_lock_slowpath+0x109/0xcf0 kernel/locking/qspinlock.c:219 > pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:572 [inline] > queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline] > queued_spin_lock include/asm-generic/qspinlock.h:114 [inline] > do_raw_spin_lock+0x20e/0x2b0 kernel/locking/spinlock_debug.c:116 > __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline] > _raw_spin_lock_irqsave+0x42/0x60 kernel/locking/spinlock.c:162 > __bpf_ringbuf_reserve+0x36e/0x4b0 kernel/bpf/ringbuf.c:423 > ____bpf_ringbuf_reserve kernel/bpf/ringbuf.c:474 [inline] > bpf_ringbuf_reserve+0x57/0x90 kernel/bpf/ringbuf.c:466 > bpf_prog_385141c453c15099+0x36/0x5d > bpf_dispatcher_nop_func include/linux/bpf.h:1316 [inline] > __bpf_prog_run include/linux/filter.h:718 [inline] > bpf_prog_run include/linux/filter.h:725 [inline] > __bpf_trace_run kernel/trace/bpf_trace.c:2363 [inline] > bpf_trace_run2+0x230/0x590 kernel/trace/bpf_trace.c:2404 > __bpf_trace_contention_begin+0xc9/0x110 include/trace/events/lock.h:95 > __traceiter_contention_begin+0x5a/0xa0 include/trace/events/lock.h:95 > __do_trace_contention_begin include/trace/events/lock.h:95 [inline] > trace_contention_begin+0xc1/0x130 include/trace/events/lock.h:95 > __mutex_lock_common kernel/locking/mutex.c:603 [inline] > __mutex_lock+0x1a6/0xb90 kernel/locking/mutex.c:746 > srcu_advance_state kernel/rcu/srcutree.c:1701 [inline] > process_srcu+0x73/0x1920 kernel/rcu/srcutree.c:1861 > process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238 > process_scheduled_works kernel/workqueue.c:3319 [inline] > worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 > kthread+0x3c2/0x780 kernel/kthread.c:464 > ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 > > > > Tested on: > > commit: e618ee89 Merge tag 'spi-fix-v6.15-rc1' of git://git.ke.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=10461c04580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=36c5de4d99134dda > dashboard link: https://syzkaller.appspot.com/bug?extid=850aaf14624dc0c6d366 > compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 > > Note: no patches were applied. #syz test: https://github.com/kkdwivedi/linux.git res-lock-next