* [PATCH] mm/z3fold.c: remove z3fold_migration trylock
@ 2019-07-10 21:32 Henry Burns
2019-07-10 21:39 ` Shakeel Butt
0 siblings, 1 reply; 3+ messages in thread
From: Henry Burns @ 2019-07-10 21:32 UTC (permalink / raw)
To: Vitaly Wool, Andrew Morton
Cc: Vitaly Vul, Shakeel Butt, Jonathan Adams, Greg Kroah-Hartman,
Snild Dolkow, Thomas Gleixner, linux-mm, linux-kernel,
Henry Burns
z3fold_page_migrate() will never succeed because it attempts to acquire a
lock that has already been taken by migrate.c in __unmap_and_move().
__unmap_and_move() migrate.c
trylock_page(oldpage)
move_to_new_page(oldpage_newpage)
a_ops->migrate_page(oldpage, newpage)
z3fold_page_migrate(oldpage, newpage)
trylock_page(oldpage)
Signed-off-by: Henry Burns <henryburns@google.com>
---
mm/z3fold.c | 6 ------
1 file changed, 6 deletions(-)
diff --git a/mm/z3fold.c b/mm/z3fold.c
index 985732c8b025..9fe9330ab8ae 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -1335,16 +1335,11 @@ static int z3fold_page_migrate(struct address_space *mapping, struct page *newpa
zhdr = page_address(page);
pool = zhdr_to_pool(zhdr);
- if (!trylock_page(page))
- return -EAGAIN;
-
if (!z3fold_page_trylock(zhdr)) {
- unlock_page(page);
return -EAGAIN;
}
if (zhdr->mapped_count != 0) {
z3fold_page_unlock(zhdr);
- unlock_page(page);
return -EBUSY;
}
new_zhdr = page_address(newpage);
@@ -1376,7 +1371,6 @@ static int z3fold_page_migrate(struct address_space *mapping, struct page *newpa
queue_work_on(new_zhdr->cpu, pool->compact_wq, &new_zhdr->work);
page_mapcount_reset(page);
- unlock_page(page);
put_page(page);
return 0;
}
--
2.22.0.410.gd8fdbe21b5-goog
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] mm/z3fold.c: remove z3fold_migration trylock
2019-07-10 21:32 [PATCH] mm/z3fold.c: remove z3fold_migration trylock Henry Burns
@ 2019-07-10 21:39 ` Shakeel Butt
2019-07-10 21:51 ` Henry Burns
0 siblings, 1 reply; 3+ messages in thread
From: Shakeel Butt @ 2019-07-10 21:39 UTC (permalink / raw)
To: Henry Burns
Cc: Vitaly Wool, Andrew Morton, Vitaly Vul, Jonathan Adams,
Greg Kroah-Hartman, Snild Dolkow, Thomas Gleixner, Linux MM,
LKML
On Wed, Jul 10, 2019 at 2:32 PM Henry Burns <henryburns@google.com> wrote:
>
> z3fold_page_migrate() will never succeed because it attempts to acquire a
> lock that has already been taken by migrate.c in __unmap_and_move().
>
> __unmap_and_move() migrate.c
> trylock_page(oldpage)
> move_to_new_page(oldpage_newpage)
> a_ops->migrate_page(oldpage, newpage)
> z3fold_page_migrate(oldpage, newpage)
> trylock_page(oldpage)
>
>
> Signed-off-by: Henry Burns <henryburns@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Please add the Fixes tag as well.
> ---
> mm/z3fold.c | 6 ------
> 1 file changed, 6 deletions(-)
>
> diff --git a/mm/z3fold.c b/mm/z3fold.c
> index 985732c8b025..9fe9330ab8ae 100644
> --- a/mm/z3fold.c
> +++ b/mm/z3fold.c
> @@ -1335,16 +1335,11 @@ static int z3fold_page_migrate(struct address_space *mapping, struct page *newpa
> zhdr = page_address(page);
> pool = zhdr_to_pool(zhdr);
>
> - if (!trylock_page(page))
> - return -EAGAIN;
> -
> if (!z3fold_page_trylock(zhdr)) {
> - unlock_page(page);
> return -EAGAIN;
> }
> if (zhdr->mapped_count != 0) {
> z3fold_page_unlock(zhdr);
> - unlock_page(page);
> return -EBUSY;
> }
> new_zhdr = page_address(newpage);
> @@ -1376,7 +1371,6 @@ static int z3fold_page_migrate(struct address_space *mapping, struct page *newpa
> queue_work_on(new_zhdr->cpu, pool->compact_wq, &new_zhdr->work);
>
> page_mapcount_reset(page);
> - unlock_page(page);
> put_page(page);
> return 0;
> }
> --
> 2.22.0.410.gd8fdbe21b5-goog
>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] mm/z3fold.c: remove z3fold_migration trylock
2019-07-10 21:39 ` Shakeel Butt
@ 2019-07-10 21:51 ` Henry Burns
0 siblings, 0 replies; 3+ messages in thread
From: Henry Burns @ 2019-07-10 21:51 UTC (permalink / raw)
To: Shakeel Butt
Cc: Vitaly Wool, Andrew Morton, Vitaly Vul, Jonathan Adams,
Greg Kroah-Hartman, Snild Dolkow, Thomas Gleixner, Linux MM,
LKML
> > z3fold_page_migrate() will never succeed because it attempts to acquire a
> > lock that has already been taken by migrate.c in __unmap_and_move().
> >
> > __unmap_and_move() migrate.c
> > trylock_page(oldpage)
> > move_to_new_page(oldpage_newpage)
> > a_ops->migrate_page(oldpage, newpage)
> > z3fold_page_migrate(oldpage, newpage)
> > trylock_page(oldpage)
> >
> >
> > Signed-off-by: Henry Burns <henryburns@google.com>
>
> Reviewed-by: Shakeel Butt <shakeelb@google.com>
>
> Please add the Fixes tag as well.
Fixes: 1f862989b04a ("mm/z3fold.c: support page migration")
>
> > ---
> > mm/z3fold.c | 6 ------
> > 1 file changed, 6 deletions(-)
> >
> > diff --git a/mm/z3fold.c b/mm/z3fold.c
> > index 985732c8b025..9fe9330ab8ae 100644
> > --- a/mm/z3fold.c
> > +++ b/mm/z3fold.c
> > @@ -1335,16 +1335,11 @@ static int z3fold_page_migrate(struct address_space *mapping, struct page *newpa
> > zhdr = page_address(page);
> > pool = zhdr_to_pool(zhdr);
> >
> > - if (!trylock_page(page))
> > - return -EAGAIN;
> > -
> > if (!z3fold_page_trylock(zhdr)) {
> > - unlock_page(page);
> > return -EAGAIN;
> > }
> > if (zhdr->mapped_count != 0) {
> > z3fold_page_unlock(zhdr);
> > - unlock_page(page);
> > return -EBUSY;
> > }
> > new_zhdr = page_address(newpage);
> > @@ -1376,7 +1371,6 @@ static int z3fold_page_migrate(struct address_space *mapping, struct page *newpa
> > queue_work_on(new_zhdr->cpu, pool->compact_wq, &new_zhdr->work);
> >
> > page_mapcount_reset(page);
> > - unlock_page(page);
> > put_page(page);
> > return 0;
> > }
> > --
> > 2.22.0.410.gd8fdbe21b5-goog
> >
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-07-10 21:32 [PATCH] mm/z3fold.c: remove z3fold_migration trylock Henry Burns
2019-07-10 21:39 ` Shakeel Butt
2019-07-10 21:51 ` Henry Burns
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