From: Baoquan He <bhe@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org, akpm@linux-foundation.org, mhocko@suse.com,
david@redhat.com, richardw.yang@linux.intel.com,
dan.j.williams@intel.com, osalvador@suse.de, rppt@linux.ibm.com,
bhe@redhat.com
Subject: [PATCH v3 5/7] mm/sparse.c: add note about only VMEMMAP supporting sub-section support
Date: Sat, 7 Mar 2020 16:42:27 +0800 [thread overview]
Message-ID: <20200307084229.28251-6-bhe@redhat.com> (raw)
In-Reply-To: <20200307084229.28251-1-bhe@redhat.com>
And tell check_pfn_span() gating the porper alignment and size of
hot added memory region.
And also move the code comments from inside section_deactivate()
to being above it. The code comments are reasonable for the whole
function, and the moving makes code cleaner.
Signed-off-by: Baoquan He <bhe@redhat.com>
---
mm/sparse.c | 37 ++++++++++++++++++++-----------------
1 file changed, 20 insertions(+), 17 deletions(-)
diff --git a/mm/sparse.c b/mm/sparse.c
index 2142045ab5c5..0fbd79c4ad81 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -772,6 +772,22 @@ static bool is_subsection_map_empty(struct mem_section *ms)
}
#endif
+/*
+ * To deactivate a memory region, there are 3 cases to handle across
+ * two configurations (SPARSEMEM_VMEMMAP={y,n}):
+ *
+ * 1. deactivation of a partial hot-added section (only possible in
+ * the SPARSEMEM_VMEMMAP=y case).
+ * a) section was present at memory init.
+ * b) section was hot-added post memory init.
+ * 2. deactivation of a complete hot-added section.
+ * 3. deactivation of a complete section from memory init.
+ *
+ * For 1, when subsection_map does not empty we will not be freeing the
+ * usage map, but still need to free the vmemmap range.
+ *
+ * For 2 and 3, the SPARSEMEM_VMEMMAP={y,n} cases are unified
+ */
static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
struct vmem_altmap *altmap)
{
@@ -784,23 +800,6 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
return;
empty = is_subsection_map_empty(ms);
- /*
- * There are 3 cases to handle across two configurations
- * (SPARSEMEM_VMEMMAP={y,n}):
- *
- * 1/ deactivation of a partial hot-added section (only possible
- * in the SPARSEMEM_VMEMMAP=y case).
- * a/ section was present at memory init
- * b/ section was hot-added post memory init
- * 2/ deactivation of a complete hot-added section
- * 3/ deactivation of a complete section from memory init
- *
- * For 1/, when subsection_map does not empty we will not be
- * freeing the usage map, but still need to free the vmemmap
- * range.
- *
- * For 2/ and 3/ the SPARSEMEM_VMEMMAP={y,n} cases are unified
- */
if (empty) {
unsigned long section_nr = pfn_to_section_nr(pfn);
@@ -907,6 +906,10 @@ static struct page * __meminit section_activate(int nid, unsigned long pfn,
*
* This is only intended for hotplug.
*
+ * Note that only VMEMMAP supports sub-section aligned hotplug,
+ * the proper alignment and size are gated by check_pfn_span().
+ *
+ *
* Return:
* * 0 - On success.
* * -EEXIST - Section has been present.
--
2.17.2
next prev parent reply other threads:[~2020-03-07 8:43 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-07 8:42 [PATCH v3 0/7] mm/hotplug: Only use subsection map for VMEMMAP Baoquan He
2020-03-07 8:42 ` [PATCH v3 1/7] mm/hotplug: fix hot remove failure in SPARSEMEM|!VMEMMAP case Baoquan He
2020-03-07 20:59 ` Andrew Morton
2020-03-07 22:55 ` Baoquan He
2020-03-09 8:56 ` David Hildenbrand
2020-03-09 8:58 ` David Hildenbrand
2020-03-09 13:18 ` Baoquan He
2020-03-09 13:22 ` David Hildenbrand
2020-03-09 10:13 ` Pankaj Gupta
2020-03-09 12:56 ` Michal Hocko
2020-03-07 8:42 ` [PATCH v3 2/7] mm/sparse.c: introduce new function fill_subsection_map() Baoquan He
2020-03-07 8:42 ` [PATCH v3 3/7] mm/sparse.c: introduce a new function clear_subsection_map() Baoquan He
2020-03-09 8:59 ` David Hildenbrand
2020-03-09 13:32 ` Baoquan He
2020-03-09 13:38 ` David Hildenbrand
2020-03-09 14:07 ` Baoquan He
2020-03-07 8:42 ` [PATCH v3 4/7] mm/sparse.c: only use subsection map in VMEMMAP case Baoquan He
2020-03-09 9:00 ` David Hildenbrand
2020-03-07 8:42 ` Baoquan He [this message]
2020-03-07 11:55 ` [PATCH v3 5/7] mm/sparse.c: add note about only VMEMMAP supporting sub-section support Baoquan He
2020-03-10 14:46 ` Michal Hocko
2020-03-11 4:20 ` Baoquan He
2020-03-07 8:42 ` [PATCH v3 6/7] mm/sparse.c: move subsection_map related codes together Baoquan He
2020-03-09 9:08 ` David Hildenbrand
2020-03-09 13:41 ` Baoquan He
2020-03-07 8:42 ` [PATCH v3 7/7] mm/sparse.c: Use __get_free_pages() instead in populate_section_memmap() Baoquan He
2020-03-10 14:56 ` Michal Hocko
2020-03-10 14:59 ` David Hildenbrand
2020-03-11 9:31 ` Baoquan He
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200307084229.28251-6-bhe@redhat.com \
--to=bhe@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=dan.j.williams@intel.com \
--cc=david@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@suse.com \
--cc=osalvador@suse.de \
--cc=richardw.yang@linux.intel.com \
--cc=rppt@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).