On Sat, Aug 23, 2014 at 11:23 PM, Paul E. McKenney <paul...@linux.vnet.ibm.com> wrote: > On Sat, Aug 23, 2014 at 08:26:10PM -0400, Pranith Kumar wrote: >> On Sat, Aug 23, 2014 at 12:51 PM, Paul E. McKenney >> <paul...@linux.vnet.ibm.com> wrote: >> >> > It might well! Another possibility is that the early_initcall function >> > doing the synchronize_rcu() is happening before the early_initcall >> > creating the RCU grace-period kthreads. >> > >> > Seems like we need to close both holes. Let's see how your patch works >> > for Amit, and I am testing a patch for the possible early_initcall >> > ordering issue. >> >> I checked the init call which is calling synchronize_rcu(): >> subsys_initcall(pm_sysrq_init); this is being called after >> early_initcall. >> >> The order of initcalls is early, core, postcore, arch, subsys, fs, >> device, late. So I guess that is ok. >> >> I wonder why it was not showing up in 12.04. I have a dual boot. Will >> test it out and see if I can find something. > > Me, I am wondering about 7,000 callbacks being registered during early > boot time. ;-) >
This is the backtrace for most of the callbacks: [ 4.612103] ------------[ cut here ]------------ [ 4.613340] WARNING: CPU: 0 PID: 0 at kernel/rcu/tree_plugin.h:2115 __call_rcu_nocb_enqueue+0x58/0x283() [ 4.615975] Modules linked in: [ 4.616000] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G W 3.16.0+ #76 [ 4.616000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 [ 4.616000] 0000000000000000 ffffffff81803c20 ffffffff813c5213 0000000000000000 [ 4.616000] ffffffff81803c58 ffffffff810388aa ffffffff8108aac8 ffff88001f9cce40 [ 4.616000] ffff88001f5b6c08 0000000000000000 0000000000000286 ffffffff81803c68 [ 4.616000] Call Trace: [ 4.616000] [<ffffffff813c5213>] dump_stack+0x4e/0x7a [ 4.616000] [<ffffffff810388aa>] warn_slowpath_common+0x7f/0x98 [ 4.616000] [<ffffffff8108aac8>] ? __call_rcu_nocb_enqueue+0x58/0x283 [ 4.616000] [<ffffffff81038976>] warn_slowpath_null+0x1a/0x1c [ 4.616000] [<ffffffff8108aac8>] __call_rcu_nocb_enqueue+0x58/0x283 [ 4.616000] [<ffffffff81129f3a>] ? unreferenced_object+0x4f/0x4f [ 4.616000] [<ffffffff8108d913>] __call_rcu+0xcd/0x32b [ 4.616000] [<ffffffff8108de66>] call_rcu+0x1b/0x1d [ 4.616000] [<ffffffff8112a301>] put_object+0x41/0x44 [ 4.616000] [<ffffffff8112a70a>] delete_object_full+0x29/0x2c [ 4.616000] [<ffffffff813c2166>] kmemleak_free+0x25/0x43 [ 4.616000] [<ffffffff81120cca>] slab_free_hook+0x1d/0x63 [ 4.616000] [<ffffffff811228c6>] kmem_cache_free+0x52/0x154 [ 4.616000] [<ffffffff8124aa01>] ? acpi_os_release_object+0xe/0x12 [ 4.616000] [<ffffffff8124aa01>] acpi_os_release_object+0xe/0x12 [ 4.616000] [<ffffffff8126c567>] acpi_ps_free_op+0x25/0x27 [ 4.616000] [<ffffffff8126b81f>] acpi_ps_create_op+0x135/0x209 [ 4.616000] [<ffffffff8126b1f2>] acpi_ps_parse_loop+0x1d3/0x575 [ 4.616000] [<ffffffff8126bff2>] acpi_ps_parse_aml+0xa0/0x277 [ 4.616000] [<ffffffff81267d7f>] acpi_ns_one_complete_parse+0xfc/0x11b [ 4.616000] [<ffffffff81267dd1>] acpi_ns_parse_table+0x33/0x38 [ 4.616000] [<ffffffff81267755>] acpi_ns_load_table+0x4c/0x8b [ 4.616000] [<ffffffff81ad6797>] acpi_load_tables+0x9d/0x15d [ 4.616000] [<ffffffff81ad5b44>] acpi_early_init+0x73/0xfe [ 4.616000] [<ffffffff81aa5e8e>] start_kernel+0x3a9/0x40a [ 4.616000] [<ffffffff81aa5120>] ? early_idt_handlers+0x120/0x120 [ 4.616000] [<ffffffff81aa54ba>] x86_64_start_reservations+0x2a/0x2c [ 4.616000] [<ffffffff81aa55f8>] x86_64_start_kernel+0x13c/0x149 [ 4.616000] ---[ end trace 8dbfee90ca96696c ]--- -- Pranith -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
