From: osalvador@suse.de
To: Dave Hansen <dave.hansen@intel.com>
Cc: Michal Hocko <mhocko@suse.com>,
Wei Yang <richard.weiyang@gmail.com>,
akpm@linux-foundation.org, linux-mm@kvack.org,
owner-linux-mm@kvack.org
Subject: Re: [PATCH] mm, sparse: drop pgdat_resize_lock in sparse_add/remove_one_section()
Date: Tue, 27 Nov 2018 08:52:14 +0100 [thread overview]
Message-ID: <4fe3f8203a35ea01c9e0ed87c361465e@suse.de> (raw)
In-Reply-To: <3356e00d-9135-12ef-a53f-49d815b8fbfc@intel.com>
> I think mem_hotplug_lock protects this case these days, though. I
> don't
> think we had it in the early days and were just slumming it with the
> pgdat locks.
Yes, it does.
>
> I really don't like the idea of removing the lock by just saying it
> doesn't protect anything without doing some homework first, though. It
> would actually be really nice to comment the entire call chain from the
> mem_hotplug_lock acquisition to here. There is precious little
> commenting in there and it could use some love.
[hot-add operation]
add_memory_resource : acquire mem_hotplug lock
arch_add_memory
add_pages
__add_pages
__add_section
sparse_add_one_section
sparse_init_one_section
[hot-remove operation]
__remove_memory : acquire mem_hotplug lock
arch_remove_memory
__remove_pages
__remove_section
sparse_remove_one_section
Both operations are serialized by the mem_hotplug lock, so they cannot
step on each other's feet.
Now, there seems to be an agreement/thought to remove the global
mem_hotplug lock, in favor of a range locking for hot-add/remove and
online/offline stage.
So, although removing the lock here is pretty straightforward, it does
not really get us closer to that goal IMHO, if that is what we want to
do in the end.
next prev parent reply other threads:[~2018-11-27 7:52 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-27 2:36 [PATCH] mm, sparse: drop pgdat_resize_lock in sparse_add/remove_one_section() Wei Yang
2018-11-27 6:25 ` Michal Hocko
2018-11-27 7:17 ` Dave Hansen
2018-11-27 7:30 ` Michal Hocko
2018-11-27 7:52 ` osalvador [this message]
2018-11-27 8:00 ` Michal Hocko
2018-11-27 8:18 ` osalvador
2018-11-28 0:29 ` Wei Yang
2018-11-28 8:19 ` Oscar Salvador
2018-11-28 8:41 ` Wei Yang
2018-11-28 1:01 ` Wei Yang
2018-11-28 8:47 ` Wei Yang
2018-11-28 9:17 ` Wei Yang
2018-11-28 12:34 ` Michal Hocko
2018-11-28 9:12 ` [PATCH v2] " Wei Yang
2018-11-28 10:28 ` David Hildenbrand
2018-11-29 8:54 ` Michal Hocko
2018-11-29 9:29 ` Wei Yang
2018-11-29 15:53 ` [PATCH v3 1/2] " Wei Yang
2018-11-29 15:53 ` [PATCH v3 2/2] mm, sparse: pass nid instead of pgdat to sparse_add_one_section() Wei Yang
2018-11-29 16:01 ` David Hildenbrand
2018-11-30 1:22 ` Wei Yang
2018-11-30 9:20 ` David Hildenbrand
2018-11-29 17:15 ` Michal Hocko
2018-11-29 23:57 ` Wei Yang
2018-11-29 16:06 ` [PATCH v3 1/2] mm, sparse: drop pgdat_resize_lock in sparse_add/remove_one_section() David Hildenbrand
2018-11-29 17:17 ` Michal Hocko
2018-11-30 4:28 ` Wei Yang
2018-11-30 9:19 ` David Hildenbrand
2018-11-30 9:52 ` Michal Hocko
2018-12-04 8:53 ` Wei Yang
2018-12-01 0:31 ` Wei Yang
2018-12-03 11:25 ` David Hildenbrand
2018-12-03 21:06 ` Wei Yang
2018-11-29 17:14 ` Michal Hocko
2018-12-04 8:56 ` [PATCH v4 " Wei Yang
2018-12-04 8:56 ` [PATCH v4 2/2] mm, sparse: pass nid instead of pgdat to sparse_add_one_section() Wei Yang
2018-12-04 9:24 ` [PATCH v4 1/2] mm, sparse: drop pgdat_resize_lock in sparse_add/remove_one_section() David Hildenbrand
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