On 10/8/2018 2:01 PM, Dan Williams wrote:
On Tue, Sep 25, 2018 at 1:29 PM Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx> wrote:The ZONE_DEVICE pages were being initialized in two locations. One was with the memory_hotplug lock held and another was outside of that lock. The problem with this is that it was nearly doubling the memory initialization time. Instead of doing this twice, once while holding a global lock and once without, I am opting to defer the initialization to the one outside of the lock. This allows us to avoid serializing the overhead for memory init and we can instead focus on per-node init times. One issue I encountered is that devm_memremap_pages and hmm_devmmem_pages_create were initializing only the pgmap field the same way. One wasn't initializing hmm_data, and the other was initializing it to a poison value. Since this is something that is exposed to the driver in the case of hmm I am opting for a third option and just initializing hmm_data to 0 since this is going to be exposed to unknown third party drivers. Reviewed-by: Pavel Tatashin <pavel.tatashin@xxxxxxxxxxxxx> Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx> --- v4: Moved moved memmap_init_zone_device to below memmmap_init_zone to avoid merge conflicts with other changes in the kernel. v5: No changeThis patch appears to cause a regression in the "create.sh" unit test in the ndctl test suite.
So all you had to do is run the create.sh script to see the issue? I just want to confirm there isn't any additional information needed before I try chasing this down.
I tried to reproduce on -next with: 2302f5ee215e mm: defer ZONE_DEVICE page initialization to the point where we init pgmap ...but -next does not even boot for me at that commit.
What version of -next? There are a couple of patches probably needed depending on which version you are trying to boot.
Here is a warning signature that proceeds a hang with this patch applied against v4.19-rc6: percpu ref (blk_queue_usage_counter_release) <= 0 (-1530626) after switching to atomic WARNING: CPU: 24 PID: 7346 at lib/percpu-refcount.c:155 percpu_ref_switch_to_atomic_rcu+0x1f7/0x200 CPU: 24 PID: 7346 Comm: modprobe Tainted: G OE 4.19.0-rc6+ #2458 [..] RIP: 0010:percpu_ref_switch_to_atomic_rcu+0x1f7/0x200 [..] Call Trace: <IRQ> ? percpu_ref_reinit+0x140/0x140 rcu_process_callbacks+0x273/0x880 __do_softirq+0xd2/0x428 irq_exit+0xf6/0x100 smp_apic_timer_interrupt+0xa2/0x220 apic_timer_interrupt+0xf/0x20 </IRQ> RIP: 0010:lock_acquire+0xb8/0x1a0 [..] ? __put_page+0x55/0x150 ? __put_page+0x55/0x150 __put_page+0x83/0x150 ? __put_page+0x55/0x150 devm_memremap_pages_release+0x194/0x250 release_nodes+0x17c/0x2c0 device_release_driver_internal+0x1a2/0x250 driver_detach+0x3a/0x70 bus_remove_driver+0x58/0xd0 __x64_sys_delete_module+0x13f/0x200 ? trace_hardirqs_off_thunk+0x1a/0x1c do_syscall_64+0x60/0x210 entry_SYSCALL_64_after_hwframe+0x49/0xbe
So it looks like we are tearing down memory when this is triggered. Do we know if this is at the end of the test or if this is running in parallel with anything?
