From: Bharata B Rao <bharata@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org, linux-mm@kvack.org
Cc: pasha.tatashin@oracle.com
Subject: Memory hotplug not increasing the total RAM
Date: Tue, 30 Jan 2018 14:00:06 +0530 [thread overview]
Message-ID: <20180130083006.GB1245@in.ibm.com> (raw)
Hi,
With the latest upstream, I see that memory hotplug is not working
as expected. The hotplugged memory isn't seen to increase the total
RAM pages. This has been observed with both x86 and Power guests.
1. Memory hotplug code intially marks pages as PageReserved via
__add_section().
2. Later the struct page gets cleared in __init_single_page().
3. Next online_pages_range() increments totalram_pages only when
PageReserved is set.
The step 2 has been introduced recently by the following commit:
commit f7f99100d8d95dbcf09e0216a143211e79418b9f
Author: Pavel Tatashin <pasha.tatashin@oracle.com>
Date: Wed Nov 15 17:36:44 2017 -0800
mm: stop zeroing memory during allocation in vmemmap
Reverting this commit restores the correct behaviour of memory hotplug.
Regards,
Bharata.
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next reply other threads:[~2018-01-30 8:30 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-30 8:30 Bharata B Rao [this message]
2018-01-30 9:16 ` Memory hotplug not increasing the total RAM Michal Hocko
2018-01-30 9:28 ` Michal Hocko
2018-01-30 9:53 ` Bharata B Rao
2018-01-30 10:11 ` Michal Hocko
2018-01-30 18:11 ` Pavel Tatashin
2018-01-30 18:29 ` Michal Hocko
2018-01-30 19:12 ` Pavel Tatashin
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