From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE9E5C65C20 for ; Mon, 8 Oct 2018 21:01:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 26638214C3 for ; Mon, 8 Oct 2018 21:01:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=intel-com.20150623.gappssmtp.com header.i=@intel-com.20150623.gappssmtp.com header.b="0UEAqn6w" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 26638214C3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726510AbeJIEOy (ORCPT ); Tue, 9 Oct 2018 00:14:54 -0400 Received: from mail-ot1-f68.google.com ([209.85.210.68]:35291 "EHLO mail-ot1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725749AbeJIEOx (ORCPT ); Tue, 9 Oct 2018 00:14:53 -0400 Received: by mail-ot1-f68.google.com with SMTP id j9-v6so21324544otl.2 for ; Mon, 08 Oct 2018 14:01:15 -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=4e8A7Ph01eerhw9OYVEjCyP9ANKm81lBfmFFReFvvTc=; b=0UEAqn6wYS/j57cZgQm0K5KRjBnRHKMldZ6wnb4+smF5gPXynViJ6W5+4cLQNIWH6f HXuK5MSF5nl7w02/xn/i4uzE3pgmajp43ZQClBOd4zrIcG3+h0Jk/s955cRF8pslorDb iGt7Nl3MqBZzr4tK4KTP6Y/5J0FKoYqL3PpT6Znjr/LFxdMT9hSwfdK+bGV9lmRfdYE2 Uq4aRal5sTcmNw5hNskFpxPGLIlwM9FyRM2RILY1kCH1tfEL7OphPo01KvRX31rw6wYL ujeL5/LyCtTheW0iF3om5Gq8iQjNIbCzP+Bs4vu+N2hNkbEFtgzkZ5hVK0NsSL2yB2LC Dvew== 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=4e8A7Ph01eerhw9OYVEjCyP9ANKm81lBfmFFReFvvTc=; b=OrYyvHWeTXtBevz3IwoQnA/VyJolIsYlXhKi6Di99Cf8hhcGOudnUebRNJbjQ/ZUNk LGvotPa69f3t8YJOBq0ON7S++g5VgTsSQ6JoJvDKqTjMtRFP60PHkJ0mOwImIVz6YPq3 DolHtcIqaFmhsIpoCMbJFQjf47fU3UZylmGT2MrnXKLfonG4fz7MNz7vXYwI4Ngn9unK 4FKsCZosk52e7vYtcJL5nGZqlEtBkFeHAYBXPNoTQnknyyCOwNUUe6mVHgarE5zHsizC xixHdAz9VXFcspZwOafSdTppmnoDd9kRkvTmnDTDFFz+WbW7j5bZZcoJyCoMxFl6T+tB osxg== X-Gm-Message-State: ABuFfoiT66kMkWIXv4aoco2x7M+ROWJ2tSvgjTsvSr9B2fT1JZ3ISQRQ Y5EUFXPWYlRcvbZNMmmnD5/gdloW4Me1R3F6wLEP6Q== X-Google-Smtp-Source: ACcGV62Imk155zHkdag0/7cJtp/1kDQJG+Oqv4oEaGlDD8109qwjDvmwLAfdDaGbKtjRR/en0XVi2J551AlU4nNb/PY= X-Received: by 2002:a9d:2372:: with SMTP id k47mr14030035otd.98.1539032473582; Mon, 08 Oct 2018 14:01:13 -0700 (PDT) MIME-Version: 1.0 References: <20180925200551.3576.18755.stgit@localhost.localdomain> <20180925202053.3576.66039.stgit@localhost.localdomain> In-Reply-To: <20180925202053.3576.66039.stgit@localhost.localdomain> From: Dan Williams Date: Mon, 8 Oct 2018 14:01:02 -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 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. 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. 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