On 2024/3/27 22:29, Zi Yan wrote:
On 27 Mar 2024, at 10:10, Kefeng Wang wrote:Like isolate_lru_page(), make isolate_movable_page() as a wrapper around isolate_lru_folio(), since isolate_movable_page() always fails on a tail page, add a warn for tail page and return immediately. Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> --- include/linux/migrate.h | 3 +++ mm/migrate.c | 41 +++++++++++++++++++++++------------------ 2 files changed, 26 insertions(+), 18 deletions(-) diff --git a/include/linux/migrate.h b/include/linux/migrate.h index f9d92482d117..a6c38ee7246a 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -70,6 +70,7 @@ int migrate_pages(struct list_head *l, new_folio_t new, free_folio_t free, unsigned int *ret_succeeded); struct folio *alloc_migration_target(struct folio *src, unsigned long private); bool isolate_movable_page(struct page *page, isolate_mode_t mode); +bool isolate_movable_folio(struct folio *folio, isolate_mode_t mode); int migrate_huge_page_move_mapping(struct address_space *mapping, struct folio *dst, struct folio *src); @@ -91,6 +92,8 @@ static inline struct folio *alloc_migration_target(struct folio *src, { return NULL; } static inline bool isolate_movable_page(struct page *page, isolate_mode_t mode) { return false; } +static inline bool isolate_movable_folio(struct page *page, isolate_mode_t mode) + { return false; } static inline int migrate_huge_page_move_mapping(struct address_space *mapping, struct folio *dst, struct folio *src) diff --git a/mm/migrate.c b/mm/migrate.c index 2228ca681afb..b2195b6ff32c 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -57,31 +57,29 @@ #include "internal.h" -bool isolate_movable_page(struct page *page, isolate_mode_t mode) +bool isolate_movable_folio(struct folio *folio, isolate_mode_t mode) { - struct folio *folio = folio_get_nontail_page(page); const struct movable_operations *mops; /* - * Avoid burning cycles with pages that are yet under __free_pages(), + * Avoid burning cycles with folios that are yet under __free_pages(), * or just got freed under us. * - * In case we 'win' a race for a movable page being freed under us and + * In case we 'win' a race for a movable folio being freed under us and * raise its refcount preventing __free_pages() from doing its job - * the put_page() at the end of this block will take care of - * release this page, thus avoiding a nasty leakage. + * the folio_put() at the end of this block will take care of + * release this folio, thus avoiding a nasty leakage. */ - if (!folio) - goto out; + folio_get(folio);You need folio_try_get() instead. Since folio_get_nontail_page() calls get_page_unless_zero() first.
Oh, indeed, will fix.
if (unlikely(folio_test_slab(folio))) goto out_putfolio; /* Pairs with smp_wmb() in slab freeing, e.g. SLUB's __free_slab() */ smp_rmb(); /* - * Check movable flag before taking the page lock because - * we use non-atomic bitops on newly allocated page flags so - * unconditionally grabbing the lock ruins page's owner side. + * Check movable flag before taking the folio lock because + * we use non-atomic bitops on newly allocated folio flags so + * unconditionally grabbing the lock ruins folio's owner side. */ if (unlikely(!__folio_test_movable(folio))) goto out_putfolio; @@ -91,13 +89,13 @@ bool isolate_movable_page(struct page *page, isolate_mode_t mode) goto out_putfolio; /* - * As movable pages are not isolated from LRU lists, concurrent - * compaction threads can race against page migration functions - * as well as race against the releasing a page. + * As movable folios are not isolated from LRU lists, concurrent + * compaction threads can race against folio migration functions + * as well as race against the releasing a folio. * - * In order to avoid having an already isolated movable page + * In order to avoid having an already isolated movable folio * being (wrongly) re-isolated while it is under migration, - * or to avoid attempting to isolate pages being released, + * or to avoid attempting to isolate folios being released, * lets be sure we have the page lock * before proceeding with the movable page isolation steps. */ @@ -113,7 +111,7 @@ bool isolate_movable_page(struct page *page, isolate_mode_t mode) if (!mops->isolate_page(&folio->page, mode)) goto out_no_isolated; - /* Driver shouldn't use PG_isolated bit of page->flags */ + /* Driver shouldn't use PG_isolated bit of folio->flags */ WARN_ON_ONCE(folio_test_isolated(folio)); folio_set_isolated(folio); folio_unlock(folio); @@ -124,10 +122,17 @@ bool isolate_movable_page(struct page *page, isolate_mode_t mode) folio_unlock(folio); out_putfolio: folio_put(folio); -out: return false; } +bool isolate_movable_page(struct page *page, isolate_mode_t mode) +{ + if (WARN_RATELIMIT(PageTail(page), "trying to isolate tail page")) + return false;Why bother adding a warning here? There was no warning before. Also, after this series, isolate_movable_page() will be gone.
I copy from isolate_lru_page(), but as you said, it seems useless, will remove it.
Thanks.
+ + return isolate_movable_folio((struct folio *)page, mode); +} + static void putback_movable_folio(struct folio *folio) { const struct movable_operations *mops = folio_movable_ops(folio); -- 2.27.0-- Best Regards, Yan, Zi
