linux-kernel - Re: [PATCH v3 1/7] mm/hotplug: fix hot remove failure in SPARSEMEM|!VMEMMAP case

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Message-ID: <20200307225530.GC27711@MiWiFi-R3L-srv>
Date:   Sun, 8 Mar 2020 06:55:30 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org, mhocko@...e.com,
        david@...hat.com, richardw.yang@...ux.intel.com,
        dan.j.williams@...el.com, osalvador@...e.de, rppt@...ux.ibm.com
Subject: Re: [PATCH v3 1/7] mm/hotplug: fix hot remove failure in
 SPARSEMEM|!VMEMMAP case

On 03/07/20 at 12:59pm, Andrew Morton wrote:
> On Sat,  7 Mar 2020 16:42:23 +0800 Baoquan He <bhe@...hat.com> wrote:
> 
> > In section_deactivate(), pfn_to_page() doesn't work any more after
> > ms->section_mem_map is resetting to NULL in SPARSEMEM|!VMEMMAP case.
> > It caused hot remove failure:
> > 
> > kernel BUG at mm/page_alloc.c:4806!
> > invalid opcode: 0000 [#1] SMP PTI
> > CPU: 3 PID: 8 Comm: kworker/u16:0 Tainted: G        W         5.5.0-next-20200205+ #340
> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
> > Workqueue: kacpi_hotplug acpi_hotplug_work_fn
> > RIP: 0010:free_pages+0x85/0xa0
> > Call Trace:
> >  __remove_pages+0x99/0xc0
> >  arch_remove_memory+0x23/0x4d
> >  try_remove_memory+0xc8/0x130
> >  ? walk_memory_blocks+0x72/0xa0
> >  __remove_memory+0xa/0x11
> >  acpi_memory_device_remove+0x72/0x100
> >  acpi_bus_trim+0x55/0x90
> >  acpi_device_hotplug+0x2eb/0x3d0
> >  acpi_hotplug_work_fn+0x1a/0x30
> >  process_one_work+0x1a7/0x370
> >  worker_thread+0x30/0x380
> >  ? flush_rcu_work+0x30/0x30
> >  kthread+0x112/0x130
> >  ? kthread_create_on_node+0x60/0x60
> >  ret_from_fork+0x35/0x40
> > 
> > Let's move the ->section_mem_map resetting after depopulate_section_memmap()
> > to fix it.
> 
> Thanks.  I think I'll cherrypick this fix and shall await more
> review/testing input on the rest of the series.

Sure, thanks.