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Message-ID: <9fc4c31c-d5a5-60de-b5db-32fd4c77b1ee@linux.alibaba.com>
Date: Wed, 8 Feb 2023 01:27:27 +0800
From: haoxin <xhao@...ux.alibaba.com>
To: Huang Ying <ying.huang@...el.com>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
Baolin Wang <baolin.wang@...ux.alibaba.com>,
Zi Yan <ziy@...dia.com>, Yang Shi <shy828301@...il.com>,
Oscar Salvador <osalvador@...e.de>,
Matthew Wilcox <willy@...radead.org>,
Bharata B Rao <bharata@....com>,
Alistair Popple <apopple@...dia.com>,
Minchan Kim <minchan@...nel.org>,
Mike Kravetz <mike.kravetz@...cle.com>,
Hyeonggon Yoo <42.hyeyoo@...il.com>
Subject: Re: [PATCH -v4 4/9] migrate_pages: split unmap_and_move() to _unmap()
and _move()
在 2023/2/8 上午1:11, haoxin 写道:
>
> 在 2023/2/6 下午2:33, Huang Ying 写道:
>> This is a preparation patch to batch the folio unmapping and moving.
>>
>> In this patch, unmap_and_move() is split to migrate_folio_unmap() and
>> migrate_folio_move(). So, we can batch _unmap() and _move() in
>> different loops later. To pass some information between unmap and
>> move, the original unused dst->mapping and dst->private are used.
>>
>> Signed-off-by: "Huang, Ying" <ying.huang@...el.com>
>> Reviewed-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
>> Cc: Zi Yan <ziy@...dia.com>
>> Cc: Yang Shi <shy828301@...il.com>
>> Cc: Oscar Salvador <osalvador@...e.de>
>> Cc: Matthew Wilcox <willy@...radead.org>
>> Cc: Bharata B Rao <bharata@....com>
>> Cc: Alistair Popple <apopple@...dia.com>
>> Cc: haoxin <xhao@...ux.alibaba.com>
>> Cc: Minchan Kim <minchan@...nel.org>
>> Cc: Mike Kravetz <mike.kravetz@...cle.com>
>> Cc: Hyeonggon Yoo <42.hyeyoo@...il.com>
>> ---
>> include/linux/migrate.h | 1 +
>> mm/migrate.c | 170 ++++++++++++++++++++++++++++++----------
>> 2 files changed, 130 insertions(+), 41 deletions(-)
>>
>> diff --git a/include/linux/migrate.h b/include/linux/migrate.h
>> index 3ef77f52a4f0..7376074f2e1e 100644
>> --- a/include/linux/migrate.h
>> +++ b/include/linux/migrate.h
>> @@ -18,6 +18,7 @@ struct migration_target_control;
>> * - zero on page migration success;
>> */
>> #define MIGRATEPAGE_SUCCESS 0
>> +#define MIGRATEPAGE_UNMAP 1
>> /**
>> * struct movable_operations - Driver page migration
>> diff --git a/mm/migrate.c b/mm/migrate.c
>> index 9a667039c34c..0428449149f4 100644
>> --- a/mm/migrate.c
>> +++ b/mm/migrate.c
>> @@ -1009,11 +1009,53 @@ static int move_to_new_folio(struct folio
>> *dst, struct folio *src,
>> return rc;
>> }
>> -static int __unmap_and_move(struct folio *src, struct folio *dst,
>> +/*
>> + * To record some information during migration, we uses
> uses / use
>> some unused
>> + * fields (mapping and private) of struct folio of the newly allocated
>> + * destination folio. This is safe because nobody is using them
>> + * except us.
>> + */
>> +static void __migrate_folio_record(struct folio *dst,
>> + unsigned long page_was_mapped,
>> + struct anon_vma *anon_vma)
>> +{
>> + dst->mapping = (void *)anon_vma;
>> + dst->private = (void *)page_was_mapped;
>> +}
>> +
>> +static void __migrate_folio_extract(struct folio *dst,
>> + int *page_was_mappedp,
>> + struct anon_vma **anon_vmap)
>> +{
>> + *anon_vmap = (void *)dst->mapping;
>> + *page_was_mappedp = (unsigned long)dst->private;
>> + dst->mapping = NULL;
>> + dst->private = NULL;
>> +}
>> +
>> +/* Cleanup src folio upon migration success */
>> +static void migrate_folio_done(struct folio *src,
>> + enum migrate_reason reason)
>> +{
>> + /*
>> + * Compaction can migrate also non-LRU pages which are
>> + * not accounted to NR_ISOLATED_*. They can be recognized
>> + * as __PageMovable
>> + */
>> + if (likely(!__folio_test_movable(src)))
>> + mod_node_page_state(folio_pgdat(src), NR_ISOLATED_ANON +
>> + folio_is_file_lru(src), -folio_nr_pages(src));
>> +
>> + if (reason != MR_MEMORY_FAILURE)
>> + /* We release the page in page_handle_poison. */
>> + folio_put(src);
>> +}
>> +
>> +static int __migrate_folio_unmap(struct folio *src, struct folio *dst,
>> int force, enum migrate_mode mode)
>> {
>> int rc = -EAGAIN;
>> - bool page_was_mapped = false;
>> + int page_was_mapped = 0;
>> struct anon_vma *anon_vma = NULL;
>> bool is_lru = !__PageMovable(&src->page);
>> @@ -1089,8 +1131,8 @@ static int __unmap_and_move(struct folio
>> *src, struct folio *dst,
>> goto out_unlock;
>> if (unlikely(!is_lru)) {
>> - rc = move_to_new_folio(dst, src, mode);
>> - goto out_unlock_both;
>> + __migrate_folio_record(dst, page_was_mapped, anon_vma);
>> + return MIGRATEPAGE_UNMAP;
>> }
>> /*
>> @@ -1115,11 +1157,42 @@ static int __unmap_and_move(struct folio
>> *src, struct folio *dst,
>> VM_BUG_ON_FOLIO(folio_test_anon(src) &&
>> !folio_test_ksm(src) && !anon_vma, src);
>> try_to_migrate(src, 0);
>> - page_was_mapped = true;
>> + page_was_mapped = 1;
>> }
>> - if (!folio_mapped(src))
>> - rc = move_to_new_folio(dst, src, mode);
>> + if (!folio_mapped(src)) {
>> + __migrate_folio_record(dst, page_was_mapped, anon_vma);
>> + return MIGRATEPAGE_UNMAP;
>> + }
>> +
>> + if (page_was_mapped)
>> + remove_migration_ptes(src, src, false);
>> +
>> +out_unlock_both:
>> + folio_unlock(dst);
>> +out_unlock:
>> + /* Drop an anon_vma reference if we took one */
>> + if (anon_vma)
>> + put_anon_vma(anon_vma);
>> + folio_unlock(src);
>> +out:
>> +
>> + return rc;
>> +}
>> +
>> +static int __migrate_folio_move(struct folio *src, struct folio *dst,
>> + enum migrate_mode mode)
>> +{
>> + int rc;
>> + int page_was_mapped = 0;
>> + struct anon_vma *anon_vma = NULL;
>> + bool is_lru = !__PageMovable(&src->page);
>> +
>> + __migrate_folio_extract(dst, &page_was_mapped, &anon_vma);
>> +
>> + rc = move_to_new_folio(dst, src, mode);
>> + if (unlikely(!is_lru))
>> + goto out_unlock_both;
>> /*
>> * When successful, push dst to LRU immediately: so that if it
>> @@ -1142,12 +1215,10 @@ static int __unmap_and_move(struct folio
>> *src, struct folio *dst,
>> out_unlock_both:
>> folio_unlock(dst);
>> -out_unlock:
>> /* Drop an anon_vma reference if we took one */
>> if (anon_vma)
>> put_anon_vma(anon_vma);
>> folio_unlock(src);
>> -out:
>> /*
>> * If migration is successful, decrease refcount of dst,
>> * which will not free the page because new page owner increased
>> @@ -1159,19 +1230,15 @@ static int __unmap_and_move(struct folio
>> *src, struct folio *dst,
>> return rc;
>> }
>> -/*
>> - * Obtain the lock on folio, remove all ptes and migrate the folio
>> - * to the newly allocated folio in dst.
>> - */
>> -static int unmap_and_move(new_page_t get_new_page,
>> - free_page_t put_new_page,
>> - unsigned long private, struct folio *src,
>> - int force, enum migrate_mode mode,
>> - enum migrate_reason reason,
>> - struct list_head *ret)
>> +/* Obtain the lock on page, remove all ptes. */
>> +static int migrate_folio_unmap(new_page_t get_new_page, free_page_t
>> put_new_page,
>> + unsigned long private, struct folio *src,
>> + struct folio **dstp, int force,
>> + enum migrate_mode mode, enum migrate_reason reason,
>> + struct list_head *ret)
>> {
>> struct folio *dst;
>> - int rc = MIGRATEPAGE_SUCCESS;
>> + int rc = MIGRATEPAGE_UNMAP;
>> struct page *newpage = NULL;
>> if (!thp_migration_supported() && folio_test_transhuge(src))
>> @@ -1182,20 +1249,50 @@ static int unmap_and_move(new_page_t
>> get_new_page,
>> folio_clear_active(src);
>> folio_clear_unevictable(src);
>> /* free_pages_prepare() will clear PG_isolated. */
>> - goto out;
>> + list_del(&src->lru);
>> + migrate_folio_done(src, reason);
>> + return MIGRATEPAGE_SUCCESS;
>> }
>> newpage = get_new_page(&src->page, private);
>> if (!newpage)
>> return -ENOMEM;
>> dst = page_folio(newpage);
>> + *dstp = dst;
>> dst->private = NULL;
>> - rc = __unmap_and_move(src, dst, force, mode);
>> + rc = __migrate_folio_unmap(src, dst, force, mode);
>> + if (rc == MIGRATEPAGE_UNMAP)
>> + return rc;
>> +
>> + /*
>> + * A page that has not been migrated will have kept its
>> + * references and be restored.
>> + */
>> + /* restore the folio to right list. */
>> + if (rc != -EAGAIN)
>> + list_move_tail(&src->lru, ret);
>> +
>> + if (put_new_page)
>> + put_new_page(&dst->page, private);
>> + else
>> + folio_put(dst);
>> +
>> + return rc;
>> +}
>> +
>> +/* Migrate the folio to the newly allocated folio in dst. */
>> +static int migrate_folio_move(free_page_t put_new_page, unsigned
>> long private,
>> + struct folio *src, struct folio *dst,
>> + enum migrate_mode mode, enum migrate_reason reason,
>> + struct list_head *ret)
>> +{
>> + int rc;
>> +
>> + rc = __migrate_folio_move(src, dst, mode);
>> if (rc == MIGRATEPAGE_SUCCESS)
>> set_page_owner_migrate_reason(&dst->page, reason);
>> -out:
>> if (rc != -EAGAIN) {
>> /*
>> * A folio that has been migrated has all references
>> @@ -1211,20 +1308,7 @@ static int unmap_and_move(new_page_t
>> get_new_page,
>> * we want to retry.
>> */
>> if (rc == MIGRATEPAGE_SUCCESS) {
>> - /*
>> - * Compaction can migrate also non-LRU folios which are
>> - * not accounted to NR_ISOLATED_*. They can be recognized
>> - * as __folio_test_movable
>> - */
>> - if (likely(!__folio_test_movable(src)))
>> - mod_node_page_state(folio_pgdat(src), NR_ISOLATED_ANON +
>> - folio_is_file_lru(src), -folio_nr_pages(src));
>> -
>> - if (reason != MR_MEMORY_FAILURE)
>> - /*
>> - * We release the folio in page_handle_poison.
>> - */
>> - folio_put(src);
>> + migrate_folio_done(src, reason);
>> } else {
>> if (rc != -EAGAIN)
>> list_add_tail(&src->lru, ret);
>> @@ -1516,7 +1600,7 @@ static int migrate_pages_batch(struct list_head
>> *from, new_page_t get_new_page,
>> int pass = 0;
>> bool is_large = false;
>> bool is_thp = false;
>> - struct folio *folio, *folio2;
>> + struct folio *folio, *folio2, *dst = NULL;
>> int rc, nr_pages;
>> LIST_HEAD(split_folios);
>> bool nosplit = (reason == MR_NUMA_MISPLACED);
>> @@ -1543,9 +1627,13 @@ static int migrate_pages_batch(struct
>> list_head *from, new_page_t get_new_page,
>> cond_resched();
>> - rc = unmap_and_move(get_new_page, put_new_page,
>> - private, folio, pass > 2, mode,
>> - reason, ret_folios);
>> + rc = migrate_folio_unmap(get_new_page, put_new_page,
>> private,
>> + folio, &dst, pass > 2, mode,
>> + reason, ret_folios);
>> + if (rc == MIGRATEPAGE_UNMAP)
>> + rc = migrate_folio_move(put_new_page, private,
>> + folio, dst, mode,
>> + reason, ret_folios);
> How to deal with the whole pages are ummaped success, but only part
> pages are moved success ?
Please ignore this, i get answer from patch 5.
Reviewed-by: Xin Hao <xhao@...ux.alibaba.com>
>> /*
>> * The rules are:
>> * Success: folio will be freed
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