On Wed, Apr 21, 2021 at 03:00:49PM +0800, Muchun Song wrote: > If we reuse the objcg APIs to charge LRU pages, the page_memcg() > can be changed when the LRU pages reparented. In this case, we need > to acquire the new lruvec lock. > > lruvec = mem_cgroup_page_lruvec(page); > > // The page is reparented. > > compact_lock_irqsave(&lruvec->lru_lock, &flags, cc); > > // Acquired the wrong lruvec lock and need to retry. > > But compact_lock_irqsave() only take lruvec lock as the parameter, > we cannot aware this change. If it can take the page as parameter > to acquire the lruvec lock. When the page memcg is changed, we can > use the page_memcg() detect whether we need to reacquire the new > lruvec lock. So compact_lock_irqsave() is not suitable for us. > Similar to lock_page_lruvec_irqsave(), introduce > compact_lock_page_lruvec_irqsave() to acquire the lruvec lock in > the compaction routine. > > Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> Acked-by: Roman Gushchin <guro@xxxxxx> > --- > mm/compaction.c | 27 ++++++++++++++++++++++++--- > 1 file changed, 24 insertions(+), 3 deletions(-) > > diff --git a/mm/compaction.c b/mm/compaction.c > index 1c500e697c88..082293587cc6 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -511,6 +511,29 @@ static bool compact_lock_irqsave(spinlock_t *lock, unsigned long *flags, > return true; > } > > +static struct lruvec * > +compact_lock_page_lruvec_irqsave(struct page *page, unsigned long *flags, > + struct compact_control *cc) Maybe compact_lock_page_irqsave() to make it more similar to compact_lock_irqsafe()? But it's up to you. Thanks!
