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[209.132.180.67]) by mx.google.com with ESMTP id p5-v6si17647183pgl.343.2018.10.08.15.01.31; Mon, 08 Oct 2018 15:01:45 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@intel-com.20150623.gappssmtp.com header.s=20150623 header.b=Pql407ok; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726483AbeJIFPA (ORCPT + 99 others); Tue, 9 Oct 2018 01:15:00 -0400 Received: from mail-oi1-f194.google.com ([209.85.167.194]:45857 "EHLO mail-oi1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725749AbeJIFO7 (ORCPT ); Tue, 9 Oct 2018 01:14:59 -0400 Received: by mail-oi1-f194.google.com with SMTP id e17-v6so16671800oig.12 for ; Mon, 08 Oct 2018 15:01:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=OFQbAlSVZ/4mgSkMOMvG6OsiGtbzPqAEEunYLPhiDus=; b=Pql407okiW/vDQ8rnsbWA5q00vQfhu54zLutLEqsFBr1CRWtTcm5HW+Gvlski8rt/h w02d9yhhI5jHp6qR3bR9XuA8sS9BbEv55T272D+EkuD8sWuKaH5lPv1dypC4sRD11Y0R eIWY4hHvLvetPlOP2JBGs0ZOxXBDaxtgFoXDWuDFY4trf29YwLaF6jjm5QShUtncWTIL zmRAhS4olvumgYULeKkx0haBsMvFA6AHiBRSgyUy4DT2wdTPRtFdFFyCJF8NTLIZ2iBl J/l8cfGVo41ur2/wWyF+xY0fIMMjB71br4EWmEF5YpMK3ZqMAarbeTi5sOBrpowCf0SW HBSg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=OFQbAlSVZ/4mgSkMOMvG6OsiGtbzPqAEEunYLPhiDus=; b=b8C4/ImqJVyQ9mu67kWT7w4opItfptO5p46CVQBwZSnycWYaem7Y9dzEu3Cyu0pRki WBpSY9Brxsn4/h8QGwZqe7uAwAtSQF7t/pICFaprwHlKo4vgFzpKnp8q8iCbtsm5Ncvz KQjHJldls+E3xbW/eAU1Ftd6LBQ8XUnd3yIUHVgxrpnXIcX1HwUw5WnF+16+ootfsP/0 JmkLt60Ed8dTRpTQzLIzAmlL1C55nlWriJ+VK/81H6+IpbbidTAEHfEK451DGxiXAR0c BXtHd/ArXVsyo91EgkzWwwAx4xDW/RViKifWMEe/0Teskh4aF3TJvIOqvBEsPQ7I5h35 QRdw== X-Gm-Message-State: ABuFfog8uNAtf9IU9ijTGnSSugrBd8jIpnFBDvjncy+wwvkjFO6bpYvp 890Rx2efW5YkB2nEhTFXmrBQRcRYihxlMWPmQarT2g== X-Received: by 2002:aca:1c19:: with SMTP id c25-v6mr5157909oic.246.1539036068903; Mon, 08 Oct 2018 15:01:08 -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 To: alexander.h.duyck@linux.intel.com Cc: Linux MM , Andrew Morton , Linux Kernel Mailing List , linux-nvdimm , Pasha Tatashin , Michal Hocko , Dave Jiang , Dave Hansen , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , rppt@linux.vnet.ibm.com, Logan Gunthorpe , Ingo Molnar , "Kirill A. Shutemov" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.