The patch titled
Subject: mm, memory_hotplug: try to migrate full pfn range
has been added to the -mm tree. Its filename is
mm-memory_hotplug-try-to-migrate-full-pfn-range.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memory_hotplug-try-to-migrate-full-pfn-range.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memory_hotplug-try-to-migrate-full-pfn-range.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Michal Hocko <mhocko@xxxxxxxx>
Subject: mm, memory_hotplug: try to migrate full pfn range
Patch series "few memory offlining enhancements".
I have been chasing memory offlining not making progress recently. On the
way I have noticed few weird decisions in the code. The migration itself
is restricted without a reasonable justification and the retry loop around
the migration is quite messy. This is addressed by patch 1 and patch 2.
Patch 3 is targeting on the faultaround code which has been a hot
candidate for the initial issue reported upstream [2] and that I am
debugging internally. It turned out to be not the main contributor in the
end but I believe we should address it regardless. See the patch
description for more details.
[1] http://lkml.kernel.org/r/20181120134323.13007-1-mhocko@xxxxxxxxxx
[2] http://lkml.kernel.org/r/20181114070909.GB2653@MiWiFi-R3L-srv
This patch (of 3):
do_migrate_range has been limiting the number of pages to migrate to 256
for some reason which is not documented. Even if the limit made some
sense back then when it was introduced it doesn't really serve a good
purpose these days. If the range contains huge pages then we break out of
the loop too early and go through LRU and pcp caches draining and
scan_movable_pages is quite suboptimal.
The only reason to limit the number of pages I can think of is to reduce
the potential time to react on the fatal signal. But even then the number
of pages is a questionable metric because even a single page migration
might block in a non-killable state (e.g. __unmap_and_move).
Remove the limit and offline the full requested range (this is one
membblock worth of pages with the current code). Should we ever get a
report that offlining takes too long to react on fatal signal then we
should rather fix the core migration to use killable waits and bailout on
a signal.
Link: http://lkml.kernel.org/r/20181211142741.2607-1-mhocko@xxxxxxxxxx
Link: http://lkml.kernel.org/r/20181211142741.2607-2-mhocko@xxxxxxxxxx
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: William Kucharski <william.kucharski@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory_hotplug.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
--- a/mm/memory_hotplug.c~mm-memory_hotplug-try-to-migrate-full-pfn-range
+++ a/mm/memory_hotplug.c
@@ -1314,18 +1314,16 @@ static struct page *new_node_page(struct
return new_page_nodemask(page, nid, &nmask);
}
-#define NR_OFFLINE_AT_ONCE_PAGES (256)
static int
do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
{
unsigned long pfn;
struct page *page;
- int move_pages = NR_OFFLINE_AT_ONCE_PAGES;
int not_managed = 0;
int ret = 0;
LIST_HEAD(source);
- for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) {
+ for (pfn = start_pfn; pfn < end_pfn; pfn++) {
if (!pfn_valid(pfn))
continue;
page = pfn_to_page(pfn);
@@ -1337,8 +1335,7 @@ do_migrate_range(unsigned long start_pfn
ret = -EBUSY;
break;
}
- if (isolate_huge_page(page, &source))
- move_pages -= 1 << compound_order(head);
+ isolate_huge_page(page, &source);
continue;
} else if (PageTransHuge(page))
pfn = page_to_pfn(compound_head(page))
@@ -1372,7 +1369,6 @@ do_migrate_range(unsigned long start_pfn
if (!ret) { /* Success */
put_page(page);
list_add_tail(&page->lru, &source);
- move_pages--;
if (!__PageMovable(page))
inc_node_page_state(page, NR_ISOLATED_ANON +
page_is_file_cache(page));
_
Patches currently in -mm which might be from mhocko@xxxxxxxx are
mm-print-more-information-about-mapping-in-__dump_page.patch
mm-lower-the-printk-loglevel-for-__dump_page-messages.patch
mm-memory_hotplug-drop-pointless-block-alignment-checks-from-__offline_pages.patch
mm-memory_hotplug-print-reason-for-the-offlining-failure.patch
mm-memory_hotplug-be-more-verbose-for-memory-offline-failures.patch
mm-memory_hotplug-be-more-verbose-for-memory-offline-failures-update.patch
mm-memory_hotplug-do-not-clear-numa_node-association-after-hot_remove.patch
hwpoison-memory_hotplug-allow-hwpoisoned-pages-to-be-offlined.patch
mm-proc-be-more-verbose-about-unstable-vma-flags-in-proc-pid-smaps.patch
mm-thp-proc-report-thp-eligibility-for-each-vma.patch
mm-proc-report-pr_set_thp_disable-in-proc.patch
mm-memory_hotplug-try-to-migrate-full-pfn-range.patch
mm-memory_hotplug-deobfuscate-migration-part-of-offlining.patch
mm-fault_around-do-not-take-a-reference-to-a-locked-page.patch
