Currently there is a leak in init_z3fold_page() -- it allocates
handles from kmem cache even for headless pages, but then they are
never used and never freed, so eventually kmem cache may get
exhausted. This patch provides a fix for that.
Reported-by: Markus Linnala <[email protected]>
Signed-off-by: Vitaly Wool <[email protected]>
---
mm/z3fold.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/mm/z3fold.c b/mm/z3fold.c
index 6397725b5ec6..7dffef2599c3 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -301,14 +301,11 @@ static void z3fold_unregister_migration(struct z3fold_pool *pool)
}
/* Initializes the z3fold header of a newly allocated z3fold page */
-static struct z3fold_header *init_z3fold_page(struct page *page,
+static struct z3fold_header *init_z3fold_page(struct page *page, bool headless,
struct z3fold_pool *pool, gfp_t gfp)
{
struct z3fold_header *zhdr = page_address(page);
- struct z3fold_buddy_slots *slots = alloc_slots(pool, gfp);
-
- if (!slots)
- return NULL;
+ struct z3fold_buddy_slots *slots;
INIT_LIST_HEAD(&page->lru);
clear_bit(PAGE_HEADLESS, &page->private);
@@ -316,6 +313,12 @@ static struct z3fold_header *init_z3fold_page(struct page *page,
clear_bit(NEEDS_COMPACTING, &page->private);
clear_bit(PAGE_STALE, &page->private);
clear_bit(PAGE_CLAIMED, &page->private);
+ if (headless)
+ return zhdr;
+
+ slots = alloc_slots(pool, gfp);
+ if (!slots)
+ return NULL;
spin_lock_init(&zhdr->page_lock);
kref_init(&zhdr->refcount);
@@ -962,7 +965,7 @@ static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
if (!page)
return -ENOMEM;
- zhdr = init_z3fold_page(page, pool, gfp);
+ zhdr = init_z3fold_page(page, bud == HEADLESS, pool, gfp);
if (!zhdr) {
__free_page(page);
return -ENOMEM;
--
2.17.1
On 9/17/19 5:53 PM, Vitaly Wool wrote:
> Currently there is a leak in init_z3fold_page() -- it allocates
> handles from kmem cache even for headless pages, but then they are
> never used and never freed, so eventually kmem cache may get
> exhausted. This patch provides a fix for that.
>
> Reported-by: Markus Linnala <[email protected]>
> Signed-off-by: Vitaly Wool <[email protected]>
Can a Fixes: commit be pinpointed, and CC stable added?
> ---
> mm/z3fold.c | 15 +++++++++------
> 1 file changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/mm/z3fold.c b/mm/z3fold.c
> index 6397725b5ec6..7dffef2599c3 100644
> --- a/mm/z3fold.c
> +++ b/mm/z3fold.c
> @@ -301,14 +301,11 @@ static void z3fold_unregister_migration(struct z3fold_pool *pool)
> }
>
> /* Initializes the z3fold header of a newly allocated z3fold page */
> -static struct z3fold_header *init_z3fold_page(struct page *page,
> +static struct z3fold_header *init_z3fold_page(struct page *page, bool headless,
> struct z3fold_pool *pool, gfp_t gfp)
> {
> struct z3fold_header *zhdr = page_address(page);
> - struct z3fold_buddy_slots *slots = alloc_slots(pool, gfp);
> -
> - if (!slots)
> - return NULL;
> + struct z3fold_buddy_slots *slots;
>
> INIT_LIST_HEAD(&page->lru);
> clear_bit(PAGE_HEADLESS, &page->private);
> @@ -316,6 +313,12 @@ static struct z3fold_header *init_z3fold_page(struct page *page,
> clear_bit(NEEDS_COMPACTING, &page->private);
> clear_bit(PAGE_STALE, &page->private);
> clear_bit(PAGE_CLAIMED, &page->private);
> + if (headless)
> + return zhdr;
> +
> + slots = alloc_slots(pool, gfp);
> + if (!slots)
> + return NULL;
>
> spin_lock_init(&zhdr->page_lock);
> kref_init(&zhdr->refcount);
> @@ -962,7 +965,7 @@ static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
> if (!page)
> return -ENOMEM;
>
> - zhdr = init_z3fold_page(page, pool, gfp);
> + zhdr = init_z3fold_page(page, bud == HEADLESS, pool, gfp);
> if (!zhdr) {
> __free_page(page);
> return -ENOMEM;
>
On Wed, Sep 18, 2019 at 9:35 AM Vlastimil Babka <[email protected]> wrote:
>
> On 9/17/19 5:53 PM, Vitaly Wool wrote:
> > Currently there is a leak in init_z3fold_page() -- it allocates
> > handles from kmem cache even for headless pages, but then they are
> > never used and never freed, so eventually kmem cache may get
> > exhausted. This patch provides a fix for that.
> >
> > Reported-by: Markus Linnala <[email protected]>
> > Signed-off-by: Vitaly Wool <[email protected]>
>
> Can a Fixes: commit be pinpointed, and CC stable added?
Fixes: 7c2b8baa61fe578 "mm/z3fold.c: add structure for buddy handles"
Best regards,
Vitaly
> > ---
> > mm/z3fold.c | 15 +++++++++------
> > 1 file changed, 9 insertions(+), 6 deletions(-)
> >
> > diff --git a/mm/z3fold.c b/mm/z3fold.c
> > index 6397725b5ec6..7dffef2599c3 100644
> > --- a/mm/z3fold.c
> > +++ b/mm/z3fold.c
> > @@ -301,14 +301,11 @@ static void z3fold_unregister_migration(struct z3fold_pool *pool)
> > }
> >
> > /* Initializes the z3fold header of a newly allocated z3fold page */
> > -static struct z3fold_header *init_z3fold_page(struct page *page,
> > +static struct z3fold_header *init_z3fold_page(struct page *page, bool headless,
> > struct z3fold_pool *pool, gfp_t gfp)
> > {
> > struct z3fold_header *zhdr = page_address(page);
> > - struct z3fold_buddy_slots *slots = alloc_slots(pool, gfp);
> > -
> > - if (!slots)
> > - return NULL;
> > + struct z3fold_buddy_slots *slots;
> >
> > INIT_LIST_HEAD(&page->lru);
> > clear_bit(PAGE_HEADLESS, &page->private);
> > @@ -316,6 +313,12 @@ static struct z3fold_header *init_z3fold_page(struct page *page,
> > clear_bit(NEEDS_COMPACTING, &page->private);
> > clear_bit(PAGE_STALE, &page->private);
> > clear_bit(PAGE_CLAIMED, &page->private);
> > + if (headless)
> > + return zhdr;
> > +
> > + slots = alloc_slots(pool, gfp);
> > + if (!slots)
> > + return NULL;
> >
> > spin_lock_init(&zhdr->page_lock);
> > kref_init(&zhdr->refcount);
> > @@ -962,7 +965,7 @@ static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
> > if (!page)
> > return -ENOMEM;
> >
> > - zhdr = init_z3fold_page(page, pool, gfp);
> > + zhdr = init_z3fold_page(page, bud == HEADLESS, pool, gfp);
> > if (!zhdr) {
> > __free_page(page);
> > return -ENOMEM;
> >
>