Hi, On 15/06/22 16:53, Juri Lelli wrote: > Hi, > > QE reported splats with signatures similar to the following (edited) > when running blktests/nvmeof-mp [1] cases. > > --->8--- > [ 329.284321] WARNING: CPU: 0 PID: 4830 at kernel/time/hrtimer.c:1294 hrtimer_start_range_ns+0xa0/0xb0 > [ 329.286298] Modules linked in: nvme_rdma(E) nvme_fabrics(E) nvme(E) nvmet_rdma(E) ... > [ 329.286354] Unloaded tainted modules: intel_uncore_frequency(E):2 isst_if_mbox_msr(E):2 ... > [ 329.296991] CPU: 0 PID: 4830 Comm: multipathd Kdump: loaded Tainted: G E -------- --- 5.19.0-0.rc1.9886142c7a22.16.test.eln120.x86_64+rt #2 > [ 329.298861] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 > [ 329.299798] RIP: 0010:hrtimer_start_range_ns+0xa0/0xb0 > [ 329.300533] Code: 41 5d 41 5e 41 5f e9 df b4 94 00 be 01 00 00 00 48 89 df e8 82 f0 ff ff eb d8 49 8b 7d 00 48 89 c6 e8 c4 b4 94 00 f3 90 eb 91 <0f> 0b eb 8d 66 66 2e 0f 1f 84 00 00 00 00 00 90 0f 1f 44 00 00 80 > [ 329.303087] RSP: 0018:ffffb4c180a1bd18 EFLAGS: 00010202 > [ 329.303817] RAX: 0000000000000001 RBX: ffffb4c180a1bd80 RCX: 0000000000000001 > [ 329.304828] RDX: 000000000000c300 RSI: 00000000000003e8 RDI: ffffb4c180a1bd80 > [ 329.305759] RBP: 00000000000003e8 R08: 00000000000003e8 R09: 0000000000000000 > [ 329.306637] R10: 0000000000000000 R11: 0000000000000001 R12: 000000000000c350 > [ 329.307510] R13: 00007efd462b3540 R14: 0000000000000001 R15: 0000000000000000 > [ 329.308384] FS: 00007efd462b5600(0000) GS:ffff8d30bbc00000(0000) knlGS:0000000000000000 > [ 329.309368] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 329.310071] CR2: 00007efd4628f000 CR3: 000000011ba62004 CR4: 00000000007706f0 > [ 329.310939] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 329.311811] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 329.312680] PKRU: 55555554 > [ 329.313022] Call Trace: > [ 329.313352] <TASK> > [ 329.313632] read_events+0xd5/0x180 > [ 329.314086] ? fget+0x79/0xa0 > [ 329.314519] ? __hrtimer_init+0xe0/0xe0 > [ 329.315056] do_io_getevents+0x71/0xd0 > [ 329.315580] __x64_sys_io_getevents+0x58/0xc0 > [ 329.316130] do_syscall_64+0x5b/0x80 > [ 329.316590] ? syscall_exit_to_user_mode+0x12/0x30 > [ 329.317192] ? do_syscall_64+0x67/0x80 > [ 329.317669] ? do_syscall_64+0x67/0x80 > [ 329.318139] ? do_syscall_64+0x67/0x80 > [ 329.318666] ? syscall_exit_to_user_mode+0x12/0x30 > [ 329.319337] ? do_syscall_64+0x67/0x80 > [ 329.319851] ? do_syscall_64+0x67/0x80 > [ 329.320396] ? syscall_exit_to_user_mode+0x12/0x30 > [ 329.321062] ? do_syscall_64+0x67/0x80 > [ 329.321540] ? __irq_exit_rcu+0x72/0x160 > [ 329.322042] entry_SYSCALL_64_after_hwframe+0x46/0xb0 > [ 329.322671] RIP: 0033:0x7efd477feecd > [ 329.323128] Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 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 8b 0d 23 7f 1b 00 f7 d8 64 89 01 48 > [ 329.325462] RSP: 002b:00007efd462b34b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000d0 > [ 329.326388] RAX: ffffffffffffffda RBX: 00007efd462b5300 RCX: 00007efd477feecd > [ 329.326962] nvme nvme0: Removing ctrl: NQN "nvme-test" > [ 329.327885] RDX: 0000000000000080 RSI: 0000000000000001 RDI: 00007efd4628f000 > [ 329.328760] RBP: 00007efd4628f000 R08: 00007efd462b45a0 R09: 0000000000000000 > [ 329.329631] R10: 00007efd462b3540 R11: 0000000000000246 R12: 0000000000000001 > [ 329.330506] R13: 0000000000000000 R14: 0000000000000080 R15: 00007efd462b3540 > [ 329.331390] </TASK> > --->8--- > > My understanding is that we have > > fs/aio.c::read_events > wait_event_interruptible_hrtimeout > __wait_event_hrtimeout > hrtimer_init_sleeper_on_stack <- this might mode |=HRTIMER_MODE_HARD on RT > hrtimer_start_range_ns > WARN_ON_ONCE(!(mode & HRTIMER_MODE_HARD) ^ !timer->is_hard) > fires since the latter doesn't see the change of mode done by > init_sleeper > > The attached patch seems to cure the problem, although I'm not entirely > sure it's the cleanest fix (if I'm right at all about it :). Gentle ping about this one. Thanks! Juri > 1 - https://github.com/yizhanglinux/blktests/tree/nvme-rdma-tcp/tests/nvmeof-mp > > --->8--- > From c7bb856eef8293c3a027f63ec3dc4fec93807227 Mon Sep 17 00:00:00 2001 > From: Juri Lelli <juri.lelli@xxxxxxxxxx> > Date: Tue, 14 Jun 2022 10:58:51 +0200 > Subject: [PATCH] time/hrtimer: Embed hrtimer mode into hrtimer_sleeper > > Changes to hrtimer mode (potentially made by __hrtimer_init_sleeper() on > PREEMPT_RT) are not visible to do_nanosleep(), thus not accounted for > by hrtimer_start_expires() call paths. > > Embed hrtimer mode into hrtimer_sleeper struct, so that the same mode is > used by code following hrtimer_sleeper initialization. > > Signed-off-by: Juri Lelli <juri.lelli@xxxxxxxxxx> > --- > block/blk-mq.c | 2 +- > include/linux/hrtimer.h | 1 + > include/linux/wait.h | 2 +- > kernel/futex/pi.c | 2 +- > kernel/time/hrtimer.c | 7 ++++--- > net/core/pktgen.c | 2 +- > 6 files changed, 9 insertions(+), 7 deletions(-) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 03235ed3a792..429d5f08a7c4 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -4672,7 +4672,7 @@ static bool blk_mq_poll_hybrid(struct request_queue *q, blk_qc_t qc) > if (blk_mq_rq_state(rq) == MQ_RQ_COMPLETE) > break; > set_current_state(TASK_UNINTERRUPTIBLE); > - hrtimer_sleeper_start_expires(&hs, mode); > + hrtimer_sleeper_start_expires(&hs, hs.mode); > if (hs.task) > io_schedule(); > hrtimer_cancel(&hs.timer); > diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h > index d22418264bec..90f79b4e20c8 100644 > --- a/include/linux/hrtimer.h > +++ b/include/linux/hrtimer.h > @@ -140,6 +140,7 @@ struct hrtimer { > struct hrtimer_sleeper { > struct hrtimer timer; > struct task_struct *task; > + enum hrtimer_mode mode; > }; > > #ifdef CONFIG_64BIT > diff --git a/include/linux/wait.h b/include/linux/wait.h > index 2d0df57c9902..b7499818f2c7 100644 > --- a/include/linux/wait.h > +++ b/include/linux/wait.h > @@ -521,7 +521,7 @@ do { \ > if ((timeout) != KTIME_MAX) \ > hrtimer_start_range_ns(&__t.timer, timeout, \ > current->timer_slack_ns, \ > - HRTIMER_MODE_REL); \ > + __t.mode); \ > \ > __ret = ___wait_event(wq_head, condition, state, 0, 0, \ > if (!__t.task) { \ > diff --git a/kernel/futex/pi.c b/kernel/futex/pi.c > index 183b28c32c83..c576e84d96c9 100644 > --- a/kernel/futex/pi.c > +++ b/kernel/futex/pi.c > @@ -1034,7 +1034,7 @@ int futex_lock_pi(u32 __user *uaddr, unsigned int flags, ktime_t *time, int tryl > } > > if (unlikely(to)) > - hrtimer_sleeper_start_expires(to, HRTIMER_MODE_ABS); > + hrtimer_sleeper_start_expires(to, to->mode); > > ret = rt_mutex_wait_proxy_lock(&q.pi_state->pi_mutex, to, &rt_waiter); > > diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c > index 0ea8702eb516..0019c802e2e8 100644 > --- a/kernel/time/hrtimer.c > +++ b/kernel/time/hrtimer.c > @@ -1996,6 +1996,7 @@ static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl, > __hrtimer_init(&sl->timer, clock_id, mode); > sl->timer.function = hrtimer_wakeup; > sl->task = current; > + sl->mode = mode; > } > > /** > @@ -2075,7 +2076,7 @@ static long __sched hrtimer_nanosleep_restart(struct restart_block *restart) > hrtimer_init_sleeper_on_stack(&t, restart->nanosleep.clockid, > HRTIMER_MODE_ABS); > hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires); > - ret = do_nanosleep(&t, HRTIMER_MODE_ABS); > + ret = do_nanosleep(&t, t.mode); > destroy_hrtimer_on_stack(&t.timer); > return ret; > } > @@ -2094,7 +2095,7 @@ long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode, > > hrtimer_init_sleeper_on_stack(&t, clockid, mode); > hrtimer_set_expires_range_ns(&t.timer, rqtp, slack); > - ret = do_nanosleep(&t, mode); > + ret = do_nanosleep(&t, t.mode); > if (ret != -ERESTART_RESTARTBLOCK) > goto out; > > @@ -2299,7 +2300,7 @@ schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta, > > hrtimer_init_sleeper_on_stack(&t, clock_id, mode); > hrtimer_set_expires_range_ns(&t.timer, *expires, delta); > - hrtimer_sleeper_start_expires(&t, mode); > + hrtimer_sleeper_start_expires(&t, t.mode); > > if (likely(t.task)) > schedule(); > diff --git a/net/core/pktgen.c b/net/core/pktgen.c > index 82c016e8c196..51eddba28c03 100644 > --- a/net/core/pktgen.c > +++ b/net/core/pktgen.c > @@ -2169,7 +2169,7 @@ static void spin(struct pktgen_dev *pkt_dev, ktime_t spin_until) > } else { > do { > set_current_state(TASK_INTERRUPTIBLE); > - hrtimer_sleeper_start_expires(&t, HRTIMER_MODE_ABS); > + hrtimer_sleeper_start_expires(&t, t.mode); > > if (likely(t.task)) > schedule(); > -- > 2.36.1
