After commit e2846124f9a2 ("zsmalloc: zs_page_migrate: skip unnecessary
loops but not return -EBUSY if zspage is not inuse") zs_page_migrate
can handle the ZS_EMPTY zspage.
But it will affect the free_work free the zspage. That will make this
ZS_EMPTY zspage stay in system until another zspage wake up free_work.
Make this patch let zs_page_migrate wake up free_work if need.
Fixes: e2846124f9a2 ("zsmalloc: zs_page_migrate: skip unnecessary loops but not return -EBUSY if zspage is not inuse")
Signed-off-by: Hui Zhu <[email protected]>
---
mm/zsmalloc.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 62457eb..48ce043 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -2035,8 +2035,14 @@ int zs_page_migrate(struct address_space *mapping, struct page *newpage,
* Page migration is done so let's putback isolated zspage to
* the list if @page is final isolated subpage in the zspage.
*/
- if (!is_zspage_isolated(zspage))
- putback_zspage(class, zspage);
+ if (!is_zspage_isolated(zspage)) {
+ /*
+ * The page and class is locked, we cannot free zspage
+ * immediately so let's defer.
+ */
+ if (putback_zspage(class, zspage) == ZS_EMPTY)
+ schedule_work(&pool->free_work);
+ }
reset_page(page);
put_page(page);
--
1.9.1
Hi Hui,
On Mon, Aug 14, 2017 at 02:34:46PM +0800, Hui Zhu wrote:
> After commit e2846124f9a2 ("zsmalloc: zs_page_migrate: skip unnecessary
> loops but not return -EBUSY if zspage is not inuse") zs_page_migrate
> can handle the ZS_EMPTY zspage.
>
> But it will affect the free_work free the zspage. That will make this
> ZS_EMPTY zspage stay in system until another zspage wake up free_work.
>
> Make this patch let zs_page_migrate wake up free_work if need.
>
> Fixes: e2846124f9a2 ("zsmalloc: zs_page_migrate: skip unnecessary loops but not return -EBUSY if zspage is not inuse")
> Signed-off-by: Hui Zhu <[email protected]>
This patch makes me remind why I didn't try to migrate empty zspage
as you did e2846124f9a2. I have forgotten it toally.
We cannot guarantee when the freeing of the page happens if we use
deferred freeing in zs_page_migrate. However, we returns
MIGRATEPAGE_SUCCESS which is totally lie.
Without instant freeing the page, it doesn't help the migration
situation. No?
I start to wonder why your patch e2846124f9a2 helped your test.
I will think over the issue with fresh mind after the holiday.
> ---
> mm/zsmalloc.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index 62457eb..48ce043 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -2035,8 +2035,14 @@ int zs_page_migrate(struct address_space *mapping, struct page *newpage,
> * Page migration is done so let's putback isolated zspage to
> * the list if @page is final isolated subpage in the zspage.
> */
> - if (!is_zspage_isolated(zspage))
> - putback_zspage(class, zspage);
> + if (!is_zspage_isolated(zspage)) {
> + /*
> + * The page and class is locked, we cannot free zspage
> + * immediately so let's defer.
> + */
> + if (putback_zspage(class, zspage) == ZS_EMPTY)
> + schedule_work(&pool->free_work);
> + }
>
> reset_page(page);
> put_page(page);
> --
> 1.9.1
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to [email protected]. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"[email protected]"> [email protected] </a>
2017-08-14 16:31 GMT+08:00 Minchan Kim <[email protected]>:
> Hi Hui,
>
> On Mon, Aug 14, 2017 at 02:34:46PM +0800, Hui Zhu wrote:
>> After commit e2846124f9a2 ("zsmalloc: zs_page_migrate: skip unnecessary
>> loops but not return -EBUSY if zspage is not inuse") zs_page_migrate
>> can handle the ZS_EMPTY zspage.
>>
>> But it will affect the free_work free the zspage. That will make this
>> ZS_EMPTY zspage stay in system until another zspage wake up free_work.
>>
>> Make this patch let zs_page_migrate wake up free_work if need.
>>
>> Fixes: e2846124f9a2 ("zsmalloc: zs_page_migrate: skip unnecessary loops but not return -EBUSY if zspage is not inuse")
>> Signed-off-by: Hui Zhu <[email protected]>
>
> This patch makes me remind why I didn't try to migrate empty zspage
> as you did e2846124f9a2. I have forgotten it toally.
>
> We cannot guarantee when the freeing of the page happens if we use
> deferred freeing in zs_page_migrate. However, we returns
> MIGRATEPAGE_SUCCESS which is totally lie.
> Without instant freeing the page, it doesn't help the migration
> situation. No?
>
Sorry I think the reason is I didn't introduce this clear.
After I patch e2846124f9a2. I got some false in zs_page_isolate:
if (get_zspage_inuse(zspage) == 0) {
spin_unlock(&class->lock);
return false;
}
The page of this zspage was migrated in before.
So I think e2846124f9a2 is OK that MIGRATEPAGE_SUCCESS with the "page".
But it keep the "newpage" with a empty zspage inside system.
Root cause is zs_page_isolate remove it from ZS_EMPTY list but not
call zs_page_putback "schedule_work(&pool->free_work);". Because
zs_page_migrate done the job without
"schedule_work(&pool->free_work);"
That is why I made the new patch.
Thanks,
Hui
> I start to wonder why your patch e2846124f9a2 helped your test.
> I will think over the issue with fresh mind after the holiday.
>
>> ---
>> mm/zsmalloc.c | 10 ++++++++--
>> 1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
>> index 62457eb..48ce043 100644
>> --- a/mm/zsmalloc.c
>> +++ b/mm/zsmalloc.c
>> @@ -2035,8 +2035,14 @@ int zs_page_migrate(struct address_space *mapping, struct page *newpage,
>> * Page migration is done so let's putback isolated zspage to
>> * the list if @page is final isolated subpage in the zspage.
>> */
>> - if (!is_zspage_isolated(zspage))
>> - putback_zspage(class, zspage);
>> + if (!is_zspage_isolated(zspage)) {
>> + /*
>> + * The page and class is locked, we cannot free zspage
>> + * immediately so let's defer.
>> + */
>> + if (putback_zspage(class, zspage) == ZS_EMPTY)
>> + schedule_work(&pool->free_work);
>> + }
>>
>> reset_page(page);
>> put_page(page);
>> --
>> 1.9.1
>>
>> --
>> To unsubscribe, send a message with 'unsubscribe linux-mm' in
>> the body to [email protected]. For more info on Linux MM,
>> see: http://www.linux-mm.org/ .
>> Don't email: <a href=mailto:"[email protected]"> [email protected] </a>
On Mon, Aug 14, 2017 at 05:11:50PM +0800, Hui Zhu wrote:
> 2017-08-14 16:31 GMT+08:00 Minchan Kim <[email protected]>:
> > Hi Hui,
> >
> > On Mon, Aug 14, 2017 at 02:34:46PM +0800, Hui Zhu wrote:
> >> After commit e2846124f9a2 ("zsmalloc: zs_page_migrate: skip unnecessary
> >> loops but not return -EBUSY if zspage is not inuse") zs_page_migrate
> >> can handle the ZS_EMPTY zspage.
> >>
> >> But it will affect the free_work free the zspage. That will make this
> >> ZS_EMPTY zspage stay in system until another zspage wake up free_work.
> >>
> >> Make this patch let zs_page_migrate wake up free_work if need.
> >>
> >> Fixes: e2846124f9a2 ("zsmalloc: zs_page_migrate: skip unnecessary loops but not return -EBUSY if zspage is not inuse")
> >> Signed-off-by: Hui Zhu <[email protected]>
> >
> > This patch makes me remind why I didn't try to migrate empty zspage
> > as you did e2846124f9a2. I have forgotten it toally.
> >
> > We cannot guarantee when the freeing of the page happens if we use
> > deferred freeing in zs_page_migrate. However, we returns
> > MIGRATEPAGE_SUCCESS which is totally lie.
> > Without instant freeing the page, it doesn't help the migration
> > situation. No?
> >
>
> Sorry I think the reason is I didn't introduce this clear.
> After I patch e2846124f9a2. I got some false in zs_page_isolate:
> if (get_zspage_inuse(zspage) == 0) {
> spin_unlock(&class->lock);
> return false;
> }
> The page of this zspage was migrated in before.
>
> So I think e2846124f9a2 is OK that MIGRATEPAGE_SUCCESS with the "page".
> But it keep the "newpage" with a empty zspage inside system.
> Root cause is zs_page_isolate remove it from ZS_EMPTY list but not
> call zs_page_putback "schedule_work(&pool->free_work);". Because
> zs_page_migrate done the job without
> "schedule_work(&pool->free_work);"
>
> That is why I made the new patch.
Thanks. Now I got it. Could you resend the patch with such detailed
information?
< snip >
> >> + if (!is_zspage_isolated(zspage)) {
> >> + /*
> >> + * The page and class is locked, we cannot free zspage
> >> + * immediately so let's defer.
Please put more words about that why we should calls schedule_work
in here.
Thanks!
> >> + */
> >> + if (putback_zspage(class, zspage) == ZS_EMPTY)
> >> + schedule_work(&pool->free_work);
> >> + }
> >>
> >> reset_page(page);
> >> put_page(page);
> >> --
> >> 1.9.1
> >>
> >> --
> >> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> >> the body to [email protected]. For more info on Linux MM,
> >> see: http://www.linux-mm.org/ .
> >> Don't email: <a href=mailto:"[email protected]"> [email protected] </a>