| Message ID | 20230210000021.1007853-1-qiang1.zhang@intel.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] sched/isolation: Fix illegal CPU value by housekeeping_any_cpu() return | expand |
Thanks for checking this! On Fri, Feb 10, 2023 at 08:00:21AM +0800, Zqiang wrote: > For kernels built with CONFIG_NO_HZ_FULL=y, running the following tests: > > runqemu kvm slirp nographic qemuparams="-m 1024 -smp 4" bootparams= > "console=ttyS0 nohz_full=0,1 rcu_nocbs=0,1 sched_verbose" -d Has this ever worked? Again I'm tempted to just: git revert 08ae95f4fd3b38b257f5dc7e6507e071c27ba0d5 > > root@qemux86-64:~# echo 0 > /sys/devices/system/cpu/cpu2/online > root@qemux86-64:~# echo 0 > /sys/devices/system/cpu/cpu3/online > > [ 22.838290] BUG: unable to handle page fault for address: ffffffff84cd48c0
On Thu, Feb 9, 2023 at 6:55 PM Zqiang <qiang1.zhang@intel.com> wrote: > > For kernels built with CONFIG_NO_HZ_FULL=y, running the following tests: > [...] > This commit therefore add checks for cpumask_any_and() return values > in housekeeping_any_cpu(), if cpumask_any_and() returns an illegal CPU > value, the housekeeping_any_cpu() will return current CPU number. > > Signed-off-by: Zqiang <qiang1.zhang@intel.com> > --- > kernel/sched/isolation.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c > index 373d42c707bc..534397ab7a36 100644 > --- a/kernel/sched/isolation.c > +++ b/kernel/sched/isolation.c > @@ -46,7 +46,11 @@ int housekeeping_any_cpu(enum hk_type type) > if (cpu < nr_cpu_ids) > return cpu; > > - return cpumask_any_and(housekeeping.cpumasks[type], cpu_online_mask); > + cpu = cpumask_any_and(housekeeping.cpumasks[type], cpu_online_mask); > + if (cpu >= nr_cpu_ids) > + return smp_processor_id(); > + else > + return cpu; Nit: no need of "else", simply: return (cpu >= nr_cpuids ? smp_processor_id() : cpu); or if (cpu >= nr_cpu_ids) return smp_processor_id(); return cpu; Thanks.
> > For kernels built with CONFIG_NO_HZ_FULL=y, running the following tests: > [...] > This commit therefore add checks for cpumask_any_and() return values > in housekeeping_any_cpu(), if cpumask_any_and() returns an illegal CPU > value, the housekeeping_any_cpu() will return current CPU number. > > Signed-off-by: Zqiang <qiang1.zhang@intel.com> > --- > kernel/sched/isolation.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c > index 373d42c707bc..534397ab7a36 100644 > --- a/kernel/sched/isolation.c > +++ b/kernel/sched/isolation.c > @@ -46,7 +46,11 @@ int housekeeping_any_cpu(enum hk_type type) > if (cpu < nr_cpu_ids) > return cpu; > > - return cpumask_any_and(housekeeping.cpumasks[type], cpu_online_mask); > + cpu = cpumask_any_and(housekeeping.cpumasks[type], cpu_online_mask); > + if (cpu >= nr_cpu_ids) > + return smp_processor_id(); > + else > + return cpu; > >Nit: no need of "else", simply: > >return (cpu >= nr_cpuids ? smp_processor_id() : cpu); Thanks Joel, I have done the same modification in v3 version, and this change is also related to a 08ae95f4fd3b, after revert it, this calltrace will disappear. Thanks Zqiang > >or > >if (cpu >= nr_cpu_ids) > return smp_processor_id(); >return cpu; > >Thanks.
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c index 373d42c707bc..534397ab7a36 100644 --- a/kernel/sched/isolation.c +++ b/kernel/sched/isolation.c @@ -46,7 +46,11 @@ int housekeeping_any_cpu(enum hk_type type) if (cpu < nr_cpu_ids) return cpu; - return cpumask_any_and(housekeeping.cpumasks[type], cpu_online_mask); + cpu = cpumask_any_and(housekeeping.cpumasks[type], cpu_online_mask); + if (cpu >= nr_cpu_ids) + return smp_processor_id(); + else + return cpu; } } return smp_processor_id();
For kernels built with CONFIG_NO_HZ_FULL=y, running the following tests: runqemu kvm slirp nographic qemuparams="-m 1024 -smp 4" bootparams= "console=ttyS0 nohz_full=0,1 rcu_nocbs=0,1 sched_verbose" -d root@qemux86-64:~# echo 0 > /sys/devices/system/cpu/cpu2/online root@qemux86-64:~# echo 0 > /sys/devices/system/cpu/cpu3/online [ 22.838290] BUG: unable to handle page fault for address: ffffffff84cd48c0 [ 22.839409] #PF: supervisor read access in kernel mode [ 22.840215] #PF: error_code(0x0000) - not-present page [ 22.841028] PGD 3e19067 P4D 3e19067 PUD 3e1a063 PMD 800ffffffb3ff062 [ 22.841889] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC KASAN PTI [ 22.842175] CPU: 0 PID: 16 Comm: rcu_preempt Not tainted 6.2.0-rc1-yocto-standard+ #658 [ 22.842534] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.o4 [ 22.843036] RIP: 0010:do_raw_spin_trylock+0x70/0x120 [ 22.843267] Code: 81 c7 00 f1 f1 f1 f1 c7 40 04 04 f3 f3 f3 65 48 8b 04 25 28 00 00 00 48 89 45 e0 31 c0 e8 b8 0 [ 22.844187] RSP: 0018:ffff8880072b7b30 EFLAGS: 00010046 [ 22.844429] RAX: 0000000000000000 RBX: ffffffff84cd48c0 RCX: dffffc0000000000 [ 22.844751] RDX: 0000000000000003 RSI: 0000000000000004 RDI: ffffffff84cd48c0 [ 22.845074] RBP: ffff8880072b7ba8 R08: ffffffff811daa20 R09: fffffbfff099a919 [ 22.845400] R10: ffffffff84cd48c3 R11: fffffbfff099a918 R12: 1ffff11000e56f66 [ 22.845719] R13: ffffffff84cd48d8 R14: ffffffff84cd48c0 R15: ffff8880072b7cd8 [ 22.846040] FS: 0000000000000000(0000) GS:ffff888035200000(0000) knlGS:0000000000000000 [ 22.846403] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 22.846667] CR2: ffffffff84cd48c0 CR3: 000000001036c000 CR4: 00000000001506f0 [ 22.846988] Call Trace: [ 22.847105] <TASK> [ 22.847208] ? __pfx_do_raw_spin_trylock+0x10/0x10 [ 22.847430] ? rcu_read_unlock+0x26/0x80 [ 22.847612] ? trace_preempt_off+0x2a/0x130 [ 22.847812] _raw_spin_lock+0x41/0x80 [ 22.847984] ? schedule_timeout+0x242/0x580 [ 22.848178] schedule_timeout+0x242/0x580 [ 22.848366] ? __pfx_schedule_timeout+0x10/0x10 [ 22.848575] ? __pfx_do_raw_spin_trylock+0x10/0x10 [ 22.848796] ? __pfx_process_timeout+0x10/0x10 [ 22.849005] ? _raw_spin_unlock_irqrestore+0x46/0x80 [ 22.849232] ? prepare_to_swait_event+0xb8/0x210 [ 22.849450] rcu_gp_fqs_loop+0x66e/0xe70 [ 22.849633] ? rcu_gp_init+0x87c/0x1130 [ 22.849813] ? __pfx_rcu_gp_fqs_loop+0x10/0x10 [ 22.850022] ? _raw_spin_unlock_irqrestore+0x46/0x80 [ 22.850251] ? finish_swait+0xce/0x100 [ 22.850429] rcu_gp_kthread+0x2ea/0x6b0 [ 22.850608] ? __pfx_do_raw_spin_trylock+0x10/0x10 [ 22.850829] ? __pfx_rcu_gp_kthread+0x10/0x10 [ 22.851039] ? __kasan_check_read+0x11/0x20 [ 22.851233] ? __kthread_parkme+0xe8/0x110 [ 22.851424] ? __pfx_rcu_gp_kthread+0x10/0x10 [ 22.851627] kthread+0x172/0x1a0 [ 22.851781] ? __pfx_kthread+0x10/0x10 [ 22.851956] ret_from_fork+0x2c/0x50 [ 22.852129] </TASK> schedule_timeout() ->__mod_timer() ->get_target_base(base, timer->flags) ->get_timer_cpu_base(tflags, get_nohz_timer_target()); ->cpu = get_nohz_timer_target() ->housekeeping_any_cpu(HK_TYPE_TIMER) /*housekeeping.cpumasks[type] is 2-3*/ /*cpu_online_mask is 0-1*/ ->cpu = cpumask_any_and(housekeeping.cpumasks[type], cpu_online_mask); /*cpu value is 4*/ ->new_base = per_cpu_ptr(&timer_bases[BASE_DEF], cpu); /*new_base is illegal address*/ ->if (base != new_base) ->raw_spin_lock(&new_base->lock); ==> trigger Oops This commit therefore add checks for cpumask_any_and() return values in housekeeping_any_cpu(), if cpumask_any_and() returns an illegal CPU value, the housekeeping_any_cpu() will return current CPU number. Signed-off-by: Zqiang <qiang1.zhang@intel.com> --- kernel/sched/isolation.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)