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@intel.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Bharata B Rao <bharata@amd.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: haoxin <xhao@linux.alibaba.com>
---
include/linux/migrate.h | 1 +
mm/migrate.c | 162 +++++++++++++++++++++++++++++-----------
2 files changed, 121 insertions(+), 42 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 97ea0737ab2b..e2383b430932 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1009,11 +1009,29 @@ 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,
+static void __migrate_folio_record(struct folio *dst,
+ unsigned long page_was_mapped,
+ struct anon_vma *anon_vma)
+{
+ dst->mapping = (struct address_space *)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 = (struct anon_vma *)dst->mapping;
+ *page_was_mappedp = (unsigned long)dst->private;
+ dst->mapping = NULL;
+ dst->private = NULL;
+}
+
+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 +1107,8 @@ 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 +1133,40 @@ 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;
+
+ __migrate_folio_extract(dst, &page_was_mapped, &anon_vma);
+
+ rc = move_to_new_folio(dst, src, mode);
/*
* When successful, push dst to LRU immediately: so that if it
@@ -1140,14 +1187,11 @@ static int __unmap_and_move(struct folio *src, struct folio *dst,
remove_migration_ptes(src,
rc == MIGRATEPAGE_SUCCESS ? dst : 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:
/*
* If migration is successful, decrease refcount of dst,
* which will not free the page because new page owner increased
@@ -1159,19 +1203,32 @@ 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)
+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);
+}
+
+/* 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 +1239,50 @@ 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 +1298,7 @@ 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);
@@ -1499,7 +1573,7 @@ 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);
@@ -1524,9 +1598,13 @@ 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);
/*
* The rules are:
* Success: folio will be freed
--
2.35.1Hi Ying,
On Tue, Dec 27, 2022 at 08:28:55AM +0800, Huang Ying wrote:
> 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@intel.com>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Yang Shi <shy828301@gmail.com>
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Matthew Wilcox <willy@infradead.org>
> Cc: Bharata B Rao <bharata@amd.com>
> Cc: Alistair Popple <apopple@nvidia.com>
> Cc: haoxin <xhao@linux.alibaba.com>
> ---
> include/linux/migrate.h | 1 +
> mm/migrate.c | 162 +++++++++++++++++++++++++++++-----------
> 2 files changed, 121 insertions(+), 42 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 97ea0737ab2b..e2383b430932 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1009,11 +1009,29 @@ 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,
> +static void __migrate_folio_record(struct folio *dst,
> + unsigned long page_was_mapped,
> + struct anon_vma *anon_vma)
> +{
> + dst->mapping = (struct address_space *)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 = (struct anon_vma *)dst->mapping;
> + *page_was_mappedp = (unsigned long)dst->private;
> + dst->mapping = NULL;
> + dst->private = NULL;
> +}
This patch as commit 42871c600cad ("migrate_pages: split
unmap_and_move() to _unmap() and _move()") in next-20230105 causes the
following error with clang when CONFIG_RANDSTRUCT is enabled, which is
the case with allmodconfig:
../mm/migrate.c:1041:15: error: casting from randomized structure pointer type 'struct address_space *' to 'struct anon_vma *'
*anon_vmap = (struct anon_vma *)dst->mapping;
^
1 error generated.
With GCC, there is only a note:
../mm/migrate.c: In function '__migrate_folio_extract':
../mm/migrate.c:1041:20: note: randstruct: casting between randomized structure pointer types (ssa): 'struct anon_vma' and 'struct address_space'
1041 | *anon_vmap = (struct anon_vma *)dst->mapping;
| ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Kees has done fixes for warnings and errors like this in the past (I
just ran
$ git log -p --grep='randomized structure pointer type'
to find them) but I did not see any that would seem appropriate here
hence just the report :)
Cheers,
Nathan
On Thu, Jan 05, 2023 at 11:26:55AM -0700, Nathan Chancellor wrote:
> Hi Ying,
>
> On Tue, Dec 27, 2022 at 08:28:55AM +0800, Huang Ying wrote:
> > 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@intel.com>
> > Cc: Zi Yan <ziy@nvidia.com>
> > Cc: Yang Shi <shy828301@gmail.com>
> > Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> > Cc: Oscar Salvador <osalvador@suse.de>
> > Cc: Matthew Wilcox <willy@infradead.org>
> > Cc: Bharata B Rao <bharata@amd.com>
> > Cc: Alistair Popple <apopple@nvidia.com>
> > Cc: haoxin <xhao@linux.alibaba.com>
> > ---
> > include/linux/migrate.h | 1 +
> > mm/migrate.c | 162 +++++++++++++++++++++++++++++-----------
> > 2 files changed, 121 insertions(+), 42 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 97ea0737ab2b..e2383b430932 100644
> > --- a/mm/migrate.c
> > +++ b/mm/migrate.c
> > @@ -1009,11 +1009,29 @@ 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,
> > +static void __migrate_folio_record(struct folio *dst,
> > + unsigned long page_was_mapped,
> > + struct anon_vma *anon_vma)
> > +{
> > + dst->mapping = (struct address_space *)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 = (struct anon_vma *)dst->mapping;
> > + *page_was_mappedp = (unsigned long)dst->private;
> > + dst->mapping = NULL;
> > + dst->private = NULL;
> > +}
>
> This patch as commit 42871c600cad ("migrate_pages: split
> unmap_and_move() to _unmap() and _move()") in next-20230105 causes the
> following error with clang when CONFIG_RANDSTRUCT is enabled, which is
> the case with allmodconfig:
>
> ../mm/migrate.c:1041:15: error: casting from randomized structure pointer type 'struct address_space *' to 'struct anon_vma *'
> *anon_vmap = (struct anon_vma *)dst->mapping;
> ^
> 1 error generated.
>
> With GCC, there is only a note:
>
> ../mm/migrate.c: In function '__migrate_folio_extract':
> ../mm/migrate.c:1041:20: note: randstruct: casting between randomized structure pointer types (ssa): 'struct anon_vma' and 'struct address_space'
>
> 1041 | *anon_vmap = (struct anon_vma *)dst->mapping;
> | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Kees has done fixes for warnings and errors like this in the past (I
> just ran
>
> $ git log -p --grep='randomized structure pointer type'
>
> to find them) but I did not see any that would seem appropriate here
> hence just the report :)
If this struct is literally just a scratch space and the original struct
layout doesn't matter, it may be possible to silence this cast by using
"(void *)" instead of the explicit struct type pointer.
--
Kees Cook
Kees Cook <keescook@chromium.org> writes:
> On Thu, Jan 05, 2023 at 11:26:55AM -0700, Nathan Chancellor wrote:
>> Hi Ying,
>>
>> On Tue, Dec 27, 2022 at 08:28:55AM +0800, Huang Ying wrote:
>> > 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@intel.com>
>> > Cc: Zi Yan <ziy@nvidia.com>
>> > Cc: Yang Shi <shy828301@gmail.com>
>> > Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
>> > Cc: Oscar Salvador <osalvador@suse.de>
>> > Cc: Matthew Wilcox <willy@infradead.org>
>> > Cc: Bharata B Rao <bharata@amd.com>
>> > Cc: Alistair Popple <apopple@nvidia.com>
>> > Cc: haoxin <xhao@linux.alibaba.com>
>> > ---
>> > include/linux/migrate.h | 1 +
>> > mm/migrate.c | 162 +++++++++++++++++++++++++++++-----------
>> > 2 files changed, 121 insertions(+), 42 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 97ea0737ab2b..e2383b430932 100644
>> > --- a/mm/migrate.c
>> > +++ b/mm/migrate.c
>> > @@ -1009,11 +1009,29 @@ 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,
>> > +static void __migrate_folio_record(struct folio *dst,
>> > + unsigned long page_was_mapped,
>> > + struct anon_vma *anon_vma)
>> > +{
>> > + dst->mapping = (struct address_space *)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 = (struct anon_vma *)dst->mapping;
>> > + *page_was_mappedp = (unsigned long)dst->private;
>> > + dst->mapping = NULL;
>> > + dst->private = NULL;
>> > +}
>>
>> This patch as commit 42871c600cad ("migrate_pages: split
>> unmap_and_move() to _unmap() and _move()") in next-20230105 causes the
>> following error with clang when CONFIG_RANDSTRUCT is enabled, which is
>> the case with allmodconfig:
>>
>> ../mm/migrate.c:1041:15: error: casting from randomized structure pointer type 'struct address_space *' to 'struct anon_vma *'
>> *anon_vmap = (struct anon_vma *)dst->mapping;
>> ^
>> 1 error generated.
>>
>> With GCC, there is only a note:
>>
>> ../mm/migrate.c: In function '__migrate_folio_extract':
>> ../mm/migrate.c:1041:20: note: randstruct: casting between randomized structure pointer types (ssa): 'struct anon_vma' and 'struct address_space'
>>
>> 1041 | *anon_vmap = (struct anon_vma *)dst->mapping;
>> | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>> Kees has done fixes for warnings and errors like this in the past (I
>> just ran
>>
>> $ git log -p --grep='randomized structure pointer type'
>>
>> to find them) but I did not see any that would seem appropriate here
>> hence just the report :)
>
> If this struct is literally just a scratch space and the original struct
> layout doesn't matter, it may be possible to silence this cast by using
> "(void *)" instead of the explicit struct type pointer.
It works! Thank you very much!
Best Regards,
Huang, Ying
On 26 Dec 2022, at 19:28, Huang Ying wrote:
> 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@intel.com>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Yang Shi <shy828301@gmail.com>
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Matthew Wilcox <willy@infradead.org>
> Cc: Bharata B Rao <bharata@amd.com>
> Cc: Alistair Popple <apopple@nvidia.com>
> Cc: haoxin <xhao@linux.alibaba.com>
> ---
> include/linux/migrate.h | 1 +
> mm/migrate.c | 162 +++++++++++++++++++++++++++++-----------
> 2 files changed, 121 insertions(+), 42 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 97ea0737ab2b..e2383b430932 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1009,11 +1009,29 @@ 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,
> +static void __migrate_folio_record(struct folio *dst,
> + unsigned long page_was_mapped,
> + struct anon_vma *anon_vma)
> +{
> + dst->mapping = (struct address_space *)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 = (struct anon_vma *)dst->mapping;
> + *page_was_mappedp = (unsigned long)dst->private;
> + dst->mapping = NULL;
> + dst->private = NULL;
> +}
> +
We probably need comments on these two functions on using dst->mapping
and dst->private. It might be hard to get the behavior later by
digging into the git log and/or looking at the code.
> +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 +1107,8 @@ 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 +1133,40 @@ 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;
> +
> + __migrate_folio_extract(dst, &page_was_mapped, &anon_vma);
> +
> + rc = move_to_new_folio(dst, src, mode);
>
> /*
> * When successful, push dst to LRU immediately: so that if it
> @@ -1140,14 +1187,11 @@ static int __unmap_and_move(struct folio *src, struct folio *dst,
> remove_migration_ptes(src,
> rc == MIGRATEPAGE_SUCCESS ? dst : 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:
> /*
> * If migration is successful, decrease refcount of dst,
> * which will not free the page because new page owner increased
> @@ -1159,19 +1203,32 @@ 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)
> +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);
> +}
> +
> +/* 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 +1239,50 @@ 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 +1298,7 @@ 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);
> @@ -1499,7 +1573,7 @@ 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);
> @@ -1524,9 +1598,13 @@ 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);
> /*
> * The rules are:
> * Success: folio will be freed
> --
> 2.35.1
--
Best Regards,
Yan, Zi
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