From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi1-x242.google.com (mail-oi1-x242.google.com [IPv6:2607:f8b0:4864:20::242]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id E6A372115C092 for ; Mon, 8 Oct 2018 15:01:09 -0700 (PDT) Received: by mail-oi1-x242.google.com with SMTP id u74-v6so16655633oia.11 for ; Mon, 08 Oct 2018 15:01:09 -0700 (PDT) MIME-Version: 1.0 References: <20180925200551.3576.18755.stgit@localhost.localdomain> <20180925202053.3576.66039.stgit@localhost.localdomain> <379e1d22-4194-6744-9e80-897b6ba126e9@linux.intel.com> In-Reply-To: <379e1d22-4194-6744-9e80-897b6ba126e9@linux.intel.com> From: Dan Williams Date: Mon, 8 Oct 2018 15:00:57 -0700 Message-ID: Subject: Re: [PATCH v5 4/4] mm: Defer ZONE_DEVICE page initialization to the point where we init pgmap List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: alexander.h.duyck@linux.intel.com Cc: Pasha Tatashin , Michal Hocko , linux-nvdimm , Dave Hansen , Linux Kernel Mailing List , Linux MM , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , rppt@linux.vnet.ibm.com, Andrew Morton , Ingo Molnar , "Kirill A. Shutemov" List-ID: On Mon, Oct 8, 2018 at 2:48 PM Alexander Duyck wrote: > > On 10/8/2018 2:01 PM, Dan Williams wrote: > > On Tue, Sep 25, 2018 at 1:29 PM Alexander Duyck > > 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 > >> Signed-off-by: Alexander Duyck > >> --- > >> > >> v4: Moved moved memmap_init_zone_device to below memmmap_init_zone to avoid > >> merge conflicts with other changes in the kernel. > >> v5: No change > > > > This 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. >>From the ndctl source tree run: make -j TESTS="create.sh" check ...the readme has some more setup instructions: https://github.com/pmem/ndctl/blob/master/README.md 0day has sometimes run this test suite automatically, but we need to get that more robust because setting up this environment is a bit of a hoop to jump through with the need to setup the nfit_test module. > > 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. Today's -next, but backed up to that above commit. I was also seeing CONFIG_DEBUG_LIST spamming the logs, and a crash in the crypto layer. > > 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: > > > > ? 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 > > > > 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? Should not be running in parallel with anything this test is performing a series of namespace setup and teardown events. Wait, where did the call to "percpu_ref_get()" go? I think that's the bug. _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm