From 7962c93e4a73d1d0b48202b38ec8c2585ce73ca6 Mon Sep 17 00:00:00 2001
From: Qian Cai <cai@lca.pw>
Date: Thu, 28 Mar 2019 20:43:34 -0700
Subject: mm/hotplug: fix offline undo_isolate_page_range()
Git-commit: 9b7ea46a82b31c74a37e6ff1c2a1df7d53e392ab
Patch-mainline: v5.1-rc3
References: bsc#1148196, VM Functionality
Commit f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded
memory to zones until online") introduced move_pfn_range_to_zone() which
calls memmap_init_zone() during onlining a memory block.
memmap_init_zone() will reset pagetype flags and makes migrate type to
be MOVABLE.
However, in __offline_pages(), it also call undo_isolate_page_range()
after offline_isolated_pages() to do the same thing. Due to commit
2ce13640b3f4 ("mm: __first_valid_page skip over offline pages") changed
__first_valid_page() to skip offline pages, undo_isolate_page_range()
here just waste CPU cycles looping around the offlining PFN range while
doing nothing, because __first_valid_page() will return NULL as
offline_isolated_pages() has already marked all memory sections within
the pfn range as offline via offline_mem_sections().
Also, after calling the "useless" undo_isolate_page_range() here, it
reaches the point of no returning by notifying MEM_OFFLINE. Those pages
will be marked as MIGRATE_MOVABLE again once onlining. The only thing
left to do is to decrease the number of isolated pageblocks zone counter
which would make some paths of the page allocation slower that the above
commit introduced.
Even if alloc_contig_range() can be used to isolate 16GB-hugetlb pages
on ppc64, an "int" should still be enough to represent the number of
pageblocks there. Fix an incorrect comment along the way.
[cai@lca.pw: v4]
Link: http://lkml.kernel.org/r/20190314150641.59358-1-cai@lca.pw
Link: http://lkml.kernel.org/r/20190313143133.46200-1-cai@lca.pw
Fixes: 2ce13640b3f4 ("mm: __first_valid_page skip over offline pages")
Signed-off-by: Qian Cai <cai@lca.pw>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org> [4.13+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/page-isolation.h | 10 ----------
mm/memory_hotplug.c | 17 +++++++++++++----
mm/page_alloc.c | 2 +-
mm/page_isolation.c | 40 ++++++++++++++++++++++++++--------------
mm/sparse.c | 2 +-
5 files changed, 41 insertions(+), 30 deletions(-)
diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h
index b2ecfeb285b4..31e37b011388 100644
--- a/include/linux/page-isolation.h
+++ b/include/linux/page-isolation.h
@@ -40,16 +40,6 @@ int move_freepages_block(struct zone *zone, struct page *page,
/*
* Changes migrate type in [start_pfn, end_pfn) to be MIGRATE_ISOLATE.
- * If specified range includes migrate types other than MOVABLE or CMA,
- * this will fail with -EBUSY.
- *
- * For isolating all pages in the range finally, the caller have to
- * free all pages in the range. test_page_isolated() can be used for
- * test it.
- *
- * The following flags are allowed (they can be combined in a bit mask)
- * SKIP_HWPOISON - ignore hwpoison pages
- * REPORT_FAILURE - report details about the failure to isolate the range
*/
int
start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 197428aafba7..d0ea0b258c4a 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1773,7 +1773,7 @@ static int __ref __offline_pages(unsigned long start_pfn,
{
unsigned long pfn, nr_pages;
long offlined_pages;
- int ret, node;
+ int ret, node, nr_isolate_pageblock;
unsigned long flags;
unsigned long valid_start, valid_end;
struct zone *zone;
@@ -1799,10 +1799,11 @@ static int __ref __offline_pages(unsigned long start_pfn,
ret = start_isolate_page_range(start_pfn, end_pfn,
MIGRATE_MOVABLE,
SKIP_HWPOISON | REPORT_FAILURE);
- if (ret) {
+ if (ret < 0) {
reason = "failure to isolate range";
goto failed_removal;
}
+ nr_isolate_pageblock = ret;
arg.start_pfn = start_pfn;
arg.nr_pages = nr_pages;
@@ -1852,8 +1853,16 @@ static int __ref __offline_pages(unsigned long start_pfn,
/* Ok, all of our target is isolated.
We cannot do rollback at this point. */
offline_isolated_pages(start_pfn, end_pfn);
- /* reset pagetype flags and makes migrate type to be MOVABLE */
- undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
+
+ /*
+ * Onlining will reset pagetype flags and makes migrate type
+ * MOVABLE, so just need to decrease the number of isolated
+ * pageblocks zone counter here.
+ */
+ spin_lock_irqsave(&zone->lock, flags);
+ zone->nr_isolate_pageblock -= nr_isolate_pageblock;
+ spin_unlock_irqrestore(&zone->lock, flags);
+
/* removal success */
adjust_managed_page_count(pfn_to_page(start_pfn), -offlined_pages);
zone->present_pages -= offlined_pages;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index bdc324bbcb98..249aa458d748 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -7650,7 +7650,7 @@ int alloc_contig_range(unsigned long start, unsigned long end,
ret = start_isolate_page_range(pfn_max_align_down(start),
pfn_max_align_up(end), migratetype, 0);
- if (ret)
+ if (ret < 0)
return ret;
/*
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index d3f965bf5173..1b3f73878ede 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -152,19 +152,28 @@ __first_valid_page(unsigned long pfn, unsigned long nr_pages)
return NULL;
}
-/*
- * start_isolate_page_range() -- make page-allocation-type of range of pages
- * to be MIGRATE_ISOLATE.
- * @start_pfn: The lower PFN of the range to be isolated.
- * @end_pfn: The upper PFN of the range to be isolated.
- * @migratetype: migrate type to set in error recovery.
+/**
+ * start_isolate_page_range() - make page-allocation-type of range of pages to
+ * be MIGRATE_ISOLATE.
+ * @start_pfn: The lower PFN of the range to be isolated.
+ * @end_pfn: The upper PFN of the range to be isolated.
+ * start_pfn/end_pfn must be aligned to pageblock_order.
+ * @migratetype: Migrate type to set in error recovery.
+ * @flags: The following flags are allowed (they can be combined in
+ * a bit mask)
+ * SKIP_HWPOISON - ignore hwpoison pages
+ * REPORT_FAILURE - report details about the failure to
+ * isolate the range
*
* Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
* the range will never be allocated. Any free pages and pages freed in the
- * future will not be allocated again.
+ * future will not be allocated again. If specified range includes migrate types
+ * other than MOVABLE or CMA, this will fail with -EBUSY. For isolating all
+ * pages in the range finally, the caller have to free all pages in the range.
+ * test_page_isolated() can be used for test it.
*
- * start_pfn/end_pfn must be aligned to pageblock_order.
- * Returns 0 on success and -EBUSY if any part of range cannot be isolated.
+ * Return: the number of isolated pageblocks on success and -EBUSY if any part
+ * of range cannot be isolated.
*/
int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
unsigned migratetype, int flags)
@@ -172,6 +181,7 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
unsigned long pfn;
unsigned long undo_pfn;
struct page *page;
+ int nr_isolate_pageblock = 0;
BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages));
@@ -180,13 +190,15 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
pfn < end_pfn;
pfn += pageblock_nr_pages) {
page = __first_valid_page(pfn, pageblock_nr_pages);
- if (page &&
- set_migratetype_isolate(page, migratetype, flags)) {
- undo_pfn = pfn;
- goto undo;
+ if (page) {
+ if (set_migratetype_isolate(page, migratetype, flags)) {
+ undo_pfn = pfn;
+ goto undo;
+ }
+ nr_isolate_pageblock++;
}
}
- return 0;
+ return nr_isolate_pageblock;
undo:
for (pfn = start_pfn;
pfn < undo_pfn;
diff --git a/mm/sparse.c b/mm/sparse.c
index d2c5dad2b1e1..3f25f3752a92 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -611,7 +611,7 @@ void online_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
}
#ifdef CONFIG_MEMORY_HOTREMOVE
-/* Mark all memory sections within the pfn range as online */
+/* Mark all memory sections within the pfn range as offline */
void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
{
unsigned long pfn;
--
2.12.3