From: David Hildenbrand <david@redhat.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-acpi@vger.kernel.org,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Andrew Morton <akpm@linux-foundation.org>,
Oscar Salvador <osalvador@suse.de>
Subject: Re: [PATCH v1] ACPI / scan: Acquire device_hotplug_lock in acpi_scan_init()
Date: Fri, 26 Jul 2019 10:05:58 +0200 [thread overview]
Message-ID: <fd9e8495-1a93-ac47-442f-081d392ed09b@redhat.com> (raw)
In-Reply-To: <20190726075729.GG6142@dhcp22.suse.cz>
On 26.07.19 09:57, Michal Hocko wrote:
> On Thu 25-07-19 22:49:36, David Hildenbrand wrote:
>> On 25.07.19 21:19, Michal Hocko wrote:
> [...]
>>> We need to rationalize the locking here, not to add more hacks.
>>
>> No, sorry. The real hack is calling a function that is *documented* to
>> be called under lock without it. That is an optimization for a special
>> case. That is the black magic in the code.
>
> OK, let me ask differently. What does the device_hotplug_lock actually
> protects from in the add_memory path? (Which data structures)
>
> This function is meant to be used when struct pages and node/zone data
> structures should be updated. Why should we even care about some device
> concept here? This should all be handled a layer up. Not all memory will
> have user space API to control online/offline state.
Via add_memory()/__add_memory() we create memory block devices for all
memory. So all memory we create via this function (IOW, hotplug) will
have user space APIs.
Sorry, I can't follow what you are saying here - are you confusing the
function we are talking about with arch_add_memory() ? (where I pulled
out the creation of memory block devices)
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2019-07-26 8:06 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-24 14:30 [PATCH v1] ACPI / scan: Acquire device_hotplug_lock in acpi_scan_init() David Hildenbrand
2019-07-25 9:11 ` Rafael J. Wysocki
2019-07-25 9:18 ` Oscar Salvador
2019-07-25 9:22 ` Rafael J. Wysocki
2019-07-25 9:23 ` David Hildenbrand
2019-07-25 12:56 ` Michal Hocko
2019-07-25 13:05 ` David Hildenbrand
2019-07-25 13:57 ` Michal Hocko
2019-07-25 14:35 ` David Hildenbrand
2019-07-25 19:19 ` Michal Hocko
2019-07-25 20:49 ` David Hildenbrand
2019-07-25 21:23 ` Rafael J. Wysocki
2019-07-26 7:20 ` David Hildenbrand
2019-07-26 7:57 ` Michal Hocko
2019-07-26 8:05 ` David Hildenbrand [this message]
2019-07-26 8:31 ` Michal Hocko
2019-07-26 8:36 ` David Hildenbrand
2019-07-26 8:44 ` Michal Hocko
2019-07-26 8:57 ` David Hildenbrand
2019-07-26 10:31 ` Michal Hocko
2019-07-26 10:37 ` David Hildenbrand
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