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linux-next/mm/page_isolation.c
Michal Hocko d381c54760 mm: only report isolation failures when offlining memory
Heiko has complained that his log is swamped by warnings from
has_unmovable_pages

[   20.536664] page dumped because: has_unmovable_pages
[   20.536792] page:000003d081ff4080 count:1 mapcount:0 mapping:000000008ff88600 index:0x0 compound_mapcount: 0
[   20.536794] flags: 0x3fffe0000010200(slab|head)
[   20.536795] raw: 03fffe0000010200 0000000000000100 0000000000000200 000000008ff88600
[   20.536796] raw: 0000000000000000 0020004100000000 ffffffff00000001 0000000000000000
[   20.536797] page dumped because: has_unmovable_pages
[   20.536814] page:000003d0823b0000 count:1 mapcount:0 mapping:0000000000000000 index:0x0
[   20.536815] flags: 0x7fffe0000000000()
[   20.536817] raw: 07fffe0000000000 0000000000000100 0000000000000200 0000000000000000
[   20.536818] raw: 0000000000000000 0000000000000000 ffffffff00000001 0000000000000000

which are not triggered by the memory hotplug but rather CMA allocator.
The original idea behind dumping the page state for all call paths was
that these messages will be helpful debugging failures.  From the above it
seems that this is not the case for the CMA path because we are lacking
much more context.  E.g the second reported page might be a CMA allocated
page.  It is still interesting to see a slab page in the CMA area but it
is hard to tell whether this is bug from the above output alone.

Address this issue by dumping the page state only on request.  Both
start_isolate_page_range and has_unmovable_pages already have an argument
to ignore hwpoison pages so make this argument more generic and turn it
into flags and allow callers to combine non-default modes into a mask.
While we are at it, has_unmovable_pages call from
is_pageblock_removable_nolock (sysfs removable file) is questionable to
report the failure so drop it from there as well.

Link: http://lkml.kernel.org/r/20181218092802.31429-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28 12:11:46 -08:00

314 lines
8.7 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* linux/mm/page_isolation.c
*/
#include <linux/mm.h>
#include <linux/page-isolation.h>
#include <linux/pageblock-flags.h>
#include <linux/memory.h>
#include <linux/hugetlb.h>
#include <linux/page_owner.h>
#include <linux/migrate.h>
#include "internal.h"
#define CREATE_TRACE_POINTS
#include <trace/events/page_isolation.h>
static int set_migratetype_isolate(struct page *page, int migratetype, int isol_flags)
{
struct zone *zone;
unsigned long flags, pfn;
struct memory_isolate_notify arg;
int notifier_ret;
int ret = -EBUSY;
zone = page_zone(page);
spin_lock_irqsave(&zone->lock, flags);
/*
* We assume the caller intended to SET migrate type to isolate.
* If it is already set, then someone else must have raced and
* set it before us. Return -EBUSY
*/
if (is_migrate_isolate_page(page))
goto out;
pfn = page_to_pfn(page);
arg.start_pfn = pfn;
arg.nr_pages = pageblock_nr_pages;
arg.pages_found = 0;
/*
* It may be possible to isolate a pageblock even if the
* migratetype is not MIGRATE_MOVABLE. The memory isolation
* notifier chain is used by balloon drivers to return the
* number of pages in a range that are held by the balloon
* driver to shrink memory. If all the pages are accounted for
* by balloons, are free, or on the LRU, isolation can continue.
* Later, for example, when memory hotplug notifier runs, these
* pages reported as "can be isolated" should be isolated(freed)
* by the balloon driver through the memory notifier chain.
*/
notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg);
notifier_ret = notifier_to_errno(notifier_ret);
if (notifier_ret)
goto out;
/*
* FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
* We just check MOVABLE pages.
*/
if (!has_unmovable_pages(zone, page, arg.pages_found, migratetype, flags))
ret = 0;
/*
* immobile means "not-on-lru" pages. If immobile is larger than
* removable-by-driver pages reported by notifier, we'll fail.
*/
out:
if (!ret) {
unsigned long nr_pages;
int mt = get_pageblock_migratetype(page);
set_pageblock_migratetype(page, MIGRATE_ISOLATE);
zone->nr_isolate_pageblock++;
nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE,
NULL);
__mod_zone_freepage_state(zone, -nr_pages, mt);
}
spin_unlock_irqrestore(&zone->lock, flags);
if (!ret)
drain_all_pages(zone);
return ret;
}
static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
{
struct zone *zone;
unsigned long flags, nr_pages;
bool isolated_page = false;
unsigned int order;
unsigned long pfn, buddy_pfn;
struct page *buddy;
zone = page_zone(page);
spin_lock_irqsave(&zone->lock, flags);
if (!is_migrate_isolate_page(page))
goto out;
/*
* Because freepage with more than pageblock_order on isolated
* pageblock is restricted to merge due to freepage counting problem,
* it is possible that there is free buddy page.
* move_freepages_block() doesn't care of merge so we need other
* approach in order to merge them. Isolation and free will make
* these pages to be merged.
*/
if (PageBuddy(page)) {
order = page_order(page);
if (order >= pageblock_order) {
pfn = page_to_pfn(page);
buddy_pfn = __find_buddy_pfn(pfn, order);
buddy = page + (buddy_pfn - pfn);
if (pfn_valid_within(buddy_pfn) &&
!is_migrate_isolate_page(buddy)) {
__isolate_free_page(page, order);
isolated_page = true;
}
}
}
/*
* If we isolate freepage with more than pageblock_order, there
* should be no freepage in the range, so we could avoid costly
* pageblock scanning for freepage moving.
*/
if (!isolated_page) {
nr_pages = move_freepages_block(zone, page, migratetype, NULL);
__mod_zone_freepage_state(zone, nr_pages, migratetype);
}
set_pageblock_migratetype(page, migratetype);
zone->nr_isolate_pageblock--;
out:
spin_unlock_irqrestore(&zone->lock, flags);
if (isolated_page) {
post_alloc_hook(page, order, __GFP_MOVABLE);
__free_pages(page, order);
}
}
static inline struct page *
__first_valid_page(unsigned long pfn, unsigned long nr_pages)
{
int i;
for (i = 0; i < nr_pages; i++) {
struct page *page;
if (!pfn_valid_within(pfn + i))
continue;
page = pfn_to_online_page(pfn + i);
if (!page)
continue;
return page;
}
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.
*
* 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.
*
* start_pfn/end_pfn must be aligned to pageblock_order.
* Return 0 on success and -EBUSY if any part of range cannot be isolated.
*
* There is no high level synchronization mechanism that prevents two threads
* from trying to isolate overlapping ranges. If this happens, one thread
* will notice pageblocks in the overlapping range already set to isolate.
* This happens in set_migratetype_isolate, and set_migratetype_isolate
* returns an error. We then clean up by restoring the migration type on
* pageblocks we may have modified and return -EBUSY to caller. This
* prevents two threads from simultaneously working on overlapping ranges.
*/
int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
unsigned migratetype, int flags)
{
unsigned long pfn;
unsigned long undo_pfn;
struct page *page;
BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages));
for (pfn = start_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;
}
}
return 0;
undo:
for (pfn = start_pfn;
pfn < undo_pfn;
pfn += pageblock_nr_pages) {
struct page *page = pfn_to_online_page(pfn);
if (!page)
continue;
unset_migratetype_isolate(page, migratetype);
}
return -EBUSY;
}
/*
* Make isolated pages available again.
*/
int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
unsigned migratetype)
{
unsigned long pfn;
struct page *page;
BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages));
for (pfn = start_pfn;
pfn < end_pfn;
pfn += pageblock_nr_pages) {
page = __first_valid_page(pfn, pageblock_nr_pages);
if (!page || !is_migrate_isolate_page(page))
continue;
unset_migratetype_isolate(page, migratetype);
}
return 0;
}
/*
* Test all pages in the range is free(means isolated) or not.
* all pages in [start_pfn...end_pfn) must be in the same zone.
* zone->lock must be held before call this.
*
* Returns the last tested pfn.
*/
static unsigned long
__test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn,
bool skip_hwpoisoned_pages)
{
struct page *page;
while (pfn < end_pfn) {
if (!pfn_valid_within(pfn)) {
pfn++;
continue;
}
page = pfn_to_page(pfn);
if (PageBuddy(page))
/*
* If the page is on a free list, it has to be on
* the correct MIGRATE_ISOLATE freelist. There is no
* simple way to verify that as VM_BUG_ON(), though.
*/
pfn += 1 << page_order(page);
else if (skip_hwpoisoned_pages && PageHWPoison(page))
/* A HWPoisoned page cannot be also PageBuddy */
pfn++;
else
break;
}
return pfn;
}
/* Caller should ensure that requested range is in a single zone */
int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
bool skip_hwpoisoned_pages)
{
unsigned long pfn, flags;
struct page *page;
struct zone *zone;
/*
* Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages
* are not aligned to pageblock_nr_pages.
* Then we just check migratetype first.
*/
for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
page = __first_valid_page(pfn, pageblock_nr_pages);
if (page && !is_migrate_isolate_page(page))
break;
}
page = __first_valid_page(start_pfn, end_pfn - start_pfn);
if ((pfn < end_pfn) || !page)
return -EBUSY;
/* Check all pages are free or marked as ISOLATED */
zone = page_zone(page);
spin_lock_irqsave(&zone->lock, flags);
pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn,
skip_hwpoisoned_pages);
spin_unlock_irqrestore(&zone->lock, flags);
trace_test_pages_isolated(start_pfn, end_pfn, pfn);
return pfn < end_pfn ? -EBUSY : 0;
}
struct page *alloc_migrate_target(struct page *page, unsigned long private)
{
return new_page_nodemask(page, numa_node_id(), &node_states[N_MEMORY]);
}