search for: trylock_page

...ing the 'page' when we get around to > + * establishing additional references. We should be the only one > + * holding a reference to the 'page' at this point. If we are not, then > + * memory corruption is possible and we should stop execution. > + */ > + BUG_ON(!trylock_page(page)); > + list_del(&page->lru); > + balloon_page_insert(b_dev_info, page); > + unlock_page(page); > + __count_vm_event(BALLOON_INFLATE); > +} > + > +/** > + * balloon_page_list_enqueue() - inserts a list of pages into the balloon page > + * list. > + * @b_...

...Block others from accessing the 'page' when we get around to + * establishing additional references. We should be the only one + * holding a reference to the 'page' at this point. If we are not, then + * memory corruption is possible and we should stop execution. + */ + BUG_ON(!trylock_page(page)); + list_del(&page->lru); + balloon_page_insert(b_dev_info, page); + unlock_page(page); + __count_vm_event(BALLOON_INFLATE); +} + +/** + * balloon_page_list_enqueue() - inserts a list of pages into the balloon page + * list. + * @b_dev_info: balloon device descriptor where we will...

...Block others from accessing the 'page' when we get around to + * establishing additional references. We should be the only one + * holding a reference to the 'page' at this point. If we are not, then + * memory corruption is possible and we should stop execution. + */ + BUG_ON(!trylock_page(page)); + list_del(&page->lru); + balloon_page_insert(b_dev_info, page); + unlock_page(page); + __count_vm_event(BALLOON_INFLATE); +} + +/** + * balloon_page_list_enqueue() - inserts a list of pages into the balloon page + * list. + * @b_dev_info: balloon device descriptor where we will...

..._info, > + struct page *page) > +{ > + /* > + * Block others from accessing the 'page' when we get around to > + * establishing additional references. We should be the only one > + * holding a reference to the 'page' at this point. > + */ > + if (!trylock_page(page)) { > + WARN_ONCE(1, "balloon inflation failed to enqueue page\n"); > + return -EFAULT; > + } > + list_del(&page->lru); > + balloon_page_insert(b_dev_info, page); > + unlock_page(page); > + __count_vm_event(BALLOON_INFLATE); > + return 0; > +} >...

..._info, > + struct page *page) > +{ > + /* > + * Block others from accessing the 'page' when we get around to > + * establishing additional references. We should be the only one > + * holding a reference to the 'page' at this point. > + */ > + if (!trylock_page(page)) { > + WARN_ONCE(1, "balloon inflation failed to enqueue page\n"); > + return -EFAULT; Looks like all callers bug on a failure. So let's just do it here, and then make this void? > + } > + list_del(&page->lru); > + balloon_page_insert(b_dev_info, page);...

...goto out; > > a_op = mapping->a_op; > if (!aop) > goto out; > if (a_op->isolate_page) > ret = 1; > out: > return ret; > > } > > It works under PG_lock but with this, we need trylock_page to peek > whether it's movable non-lru or not for scanning pfn. Hm I hoped that with READ_ONCE() we could do the peek safely without trylock_page, if we use it only as a heuristic. But I guess it would require at least RCU-level protection of the page->mapping->a_op->isolate_pag...

...goto out; > > a_op = mapping->a_op; > if (!aop) > goto out; > if (a_op->isolate_page) > ret = 1; > out: > return ret; > > } > > It works under PG_lock but with this, we need trylock_page to peek > whether it's movable non-lru or not for scanning pfn. Hm I hoped that with READ_ONCE() we could do the peek safely without trylock_page, if we use it only as a heuristic. But I guess it would require at least RCU-level protection of the page->mapping->a_op->isolate_pag...

On 05/31/2016 05:31 AM, Minchan Kim wrote: > @@ -791,6 +921,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage, > int rc = -EAGAIN; > int page_was_mapped = 0; > struct anon_vma *anon_vma = NULL; > + bool is_lru = !__PageMovable(page); > > if (!trylock_page(page)) { > if (!force || mode == MIGRATE_ASYNC) > @@ -871,6 +1002,11 @@ static int __unmap_and_move(struct page *page, struct page *newpage, > goto out_unlock_both; > } > > + if (unlikely(!is_lru)) { > + rc = move_to_new_page(newpage, page, mode); > + goto out_un...

On 05/31/2016 05:31 AM, Minchan Kim wrote: > @@ -791,6 +921,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage, > int rc = -EAGAIN; > int page_was_mapped = 0; > struct anon_vma *anon_vma = NULL; > + bool is_lru = !__PageMovable(page); > > if (!trylock_page(page)) { > if (!force || mode == MIGRATE_ASYNC) > @@ -871,6 +1002,11 @@ static int __unmap_and_move(struct page *page, struct page *newpage, > goto out_unlock_both; > } > > + if (unlikely(!is_lru)) { > + rc = move_to_new_page(newpage, page, mode); > + goto out_un...

...ULL); } +int trylock_zspage(struct page *first_page, struct page *locked_page) +{ + struct page *cursor, *fail; + + VM_BUG_ON_PAGE(!is_first_page(first_page), first_page); + + for (cursor = first_page; cursor != NULL; cursor = + get_next_page(cursor)) { + if (cursor != locked_page) { + if (!trylock_page(cursor)) { + fail = cursor; + goto unlock; + } + } + } + + return 1; +unlock: + for (cursor = first_page; cursor != fail; cursor = + get_next_page(cursor)) { + if (cursor != locked_page) + unlock_page(cursor); + } + + return 0; +} + +void unlock_zspage(struct page *first_page, struct...

...>> + /* > >> + * Block others from accessing the 'page' when we get around to > >> + * establishing additional references. We should be the only one > >> + * holding a reference to the 'page' at this point. > >> + */ > >> + if (!trylock_page(page)) { > >> + WARN_ONCE(1, "balloon inflation failed to enqueue page\n"); > >> + return -EFAULT; > > > > Looks like all callers bug on a failure. So let's just do it here, > > and then make this void? > > As you noted below, actually bal...

VMware balloon enhancements: adding support for memory compaction, memory shrinker (to prevent OOM) and splitting of refused pages to prevent recurring inflations. Patches 1-2: Support for compaction Patch 3: Support for memory shrinker - disabled by default Patch 4: Split refused pages to improve performance v2->v3: * Fixing wrong argument type (int->size_t) [Michael] * Fixing a comment

...first_entry(&b_dev_info->pages, typeof(*page), lru); + /* move to processed list to avoid going over it another time */ + list_move(&page->lru, &processed); + + if (!get_page_unless_zero(page)) + continue; + /* + * pages_lock nests within page lock, + * so drop it before trylock_page + */ + spin_unlock_irqrestore(&b_dev_info->pages_lock, flags); + /* * Block others from accessing the 'page' while we get around * establishing additional references and preparing the 'page' @@ -72,6 +94,7 @@ struct page *balloon_page_dequeue(struct balloon_dev_...

...first_entry(&b_dev_info->pages, typeof(*page), lru); + /* move to processed list to avoid going over it another time */ + list_move(&page->lru, &processed); + + if (!get_page_unless_zero(page)) + continue; + /* + * pages_lock nests within page lock, + * so drop it before trylock_page + */ + spin_unlock_irqrestore(&b_dev_info->pages_lock, flags); + /* * Block others from accessing the 'page' while we get around * establishing additional references and preparing the 'page' @@ -72,6 +94,7 @@ struct page *balloon_page_dequeue(struct balloon_dev_...

Hi Minchan, [auto build test WARNING on next-20160318] [cannot apply to v4.5-rc7 v4.5-rc6 v4.5-rc5 v4.5] [if your patch is applied to the wrong git tree, please drop us a note to help improving the system] url: https://github.com/0day-ci/linux/commits/Minchan-Kim/Support-non-lru-page-migration/20160321-143339 coccinelle warnings: (new ones prefixed by >>) >>

Hi Minchan, [auto build test WARNING on next-20160318] [cannot apply to v4.5-rc7 v4.5-rc6 v4.5-rc5 v4.5] [if your patch is applied to the wrong git tree, please drop us a note to help improving the system] url: https://github.com/0day-ci/linux/commits/Minchan-Kim/Support-non-lru-page-migration/20160321-143339 coccinelle warnings: (new ones prefixed by >>) >>

...g the ref counter, we need to re-check PageMovable() > > to ensure that we indeed handle PageMovable() type page. Without it, > > the page we handle can be freed and re-allocated to someone else > > that isn't related to PageMovable() before grabbing the page. Trying > > trylock_page() in this case could cause a problem. > > I don't get it. Why do you think trylock_page could cause a problem? > Could you elaborate it more? Okay. Consider following sequence. CPU-A CPU-B check PageMovable() in compacton ......

...g the ref counter, we need to re-check PageMovable() > > to ensure that we indeed handle PageMovable() type page. Without it, > > the page we handle can be freed and re-allocated to someone else > > that isn't related to PageMovable() before grabbing the page. Trying > > trylock_page() in this case could cause a problem. > > I don't get it. Why do you think trylock_page could cause a problem? > Could you elaborate it more? Okay. Consider following sequence. CPU-A CPU-B check PageMovable() in compacton ......

...ge *page, struct page *newpage, >>> > > int rc = -EAGAIN; >>> > > int page_was_mapped = 0; >>> > > struct anon_vma *anon_vma = NULL; >>> > > + bool is_lru = !__PageMovable(page); >>> > > >>> > > if (!trylock_page(page)) { >>> > > if (!force || mode == MIGRATE_ASYNC) >>> > > @@ -871,6 +1002,11 @@ static int __unmap_and_move(struct page *page, struct page *newpage, >>> > > goto out_unlock_both; >>> > > } >>> > > >>>...

...ge *page, struct page *newpage, >>> > > int rc = -EAGAIN; >>> > > int page_was_mapped = 0; >>> > > struct anon_vma *anon_vma = NULL; >>> > > + bool is_lru = !__PageMovable(page); >>> > > >>> > > if (!trylock_page(page)) { >>> > > if (!force || mode == MIGRATE_ASYNC) >>> > > @@ -871,6 +1002,11 @@ static int __unmap_and_move(struct page *page, struct page *newpage, >>> > > goto out_unlock_both; >>> > > } >>> > > >>>...