On Wed, Jul 29, 2020 at 01:44:15AM -0700, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 6ba1b005 Merge tag 'asm-generic-fixes-5.8' of git://git.ke..
Bit useless, having git://git.ke... there, that doesn't really narrow things down. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=14da5522900000 > kernel config: https://syzkaller.appspot.com/x/.config?x=812bbfcb6ae2cd60 > dashboard link: https://syzkaller.appspot.com/bug?extid=cb3b69ae80afd6535b0e > compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ > c2443155a0fb245c8f17f2c1c72b6ea391e86e81) > > Unfortunately, I don't have any reproducer for this issue yet. > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+cb3b69ae80afd6535...@syzkaller.appspotmail.com > > rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: > rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): > ------------[ cut here ]------------ > IRQs not enabled as expected > WARNING: CPU: 0 PID: 32297 at kernel/sched/core.c:2701 > try_invoke_on_locked_down_task+0x18b/0x320 kernel/sched/core.c:2701 > Kernel panic - not syncing: panic_on_warn set ... > CPU: 0 PID: 32297 Comm: syz-executor.2 Not tainted 5.8.0-rc7-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > <IRQ> > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x1f0/0x31e lib/dump_stack.c:118 > panic+0x264/0x7a0 kernel/panic.c:231 > __warn+0x227/0x250 kernel/panic.c:600 > report_bug+0x1b1/0x2e0 lib/bug.c:198 > handle_bug+0x42/0x80 arch/x86/kernel/traps.c:235 > exc_invalid_op+0x16/0x40 arch/x86/kernel/traps.c:255 > asm_exc_invalid_op+0x12/0x20 arch/x86/include/asm/idtentry.h:540 > RIP: 0010:try_invoke_on_locked_down_task+0x18b/0x320 kernel/sched/core.c:2701 > Code: 48 89 df e8 f7 35 09 00 4c 89 f7 e8 df b5 cf 06 e9 b5 00 00 00 c6 05 34 > 82 38 08 01 48 c7 c7 8c d7 07 89 31 c0 e8 a5 a9 f5 ff <0f> 0b e9 15 ff ff ff > 48 c7 c1 30 71 8d 89 80 e1 07 80 c1 03 38 c1 > RSP: 0018:ffffc90000007c50 EFLAGS: 00010046 > RAX: 1aaa08be6903c500 RBX: ffff888085d16ac8 RCX: ffff888085d16240 > RDX: 0000000000010004 RSI: 0000000000010004 RDI: 0000000000000000 > RBP: ffff888085d16b0c R08: ffffffff815dd389 R09: ffffed1015d041c3 > R10: ffffed1015d041c3 R11: 0000000000000000 R12: 0000000000000000 > R13: ffff8880a8bac140 R14: ffff8880a8bac4c0 R15: dffffc0000000000 > rcu_print_task_stall kernel/rcu/tree_stall.h:269 [inline] > print_other_cpu_stall kernel/rcu/tree_stall.h:477 [inline] Ha, that calls it with IRQs already disabled, So I'm thinking we want something like so? --- diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 2142c6767682..3182caf14844 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2694,12 +2694,11 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) */ bool try_invoke_on_locked_down_task(struct task_struct *p, bool (*func)(struct task_struct *t, void *arg), void *arg) { - bool ret = false; struct rq_flags rf; + bool ret = false; struct rq *rq; - lockdep_assert_irqs_enabled(); - raw_spin_lock_irq(&p->pi_lock); + raw_spin_lock_irqsave(&p->pi_lock, rf.flags); if (p->on_rq) { rq = __task_rq_lock(p, &rf); if (task_rq(p) == rq) @@ -2716,7 +2715,7 @@ bool try_invoke_on_locked_down_task(struct task_struct *p, bool (*func)(struct t ret = func(p, arg); } } - raw_spin_unlock_irq(&p->pi_lock); + raw_spin_unlock_irqrestore(&p->pi_lock, rf.flags); return ret; }
