[14/14] mm/lru: fix the comments of lru_lock

Commit Message

Alex Shi Aug. 20, 2019, 9:48 a.m. UTC

Since we changed the pgdat->lru_lock to lruvec->lru_lock, have to fix the
incorrect comments in code. Also fixed some zone->lru_lock comment error
in ancient time.

Signed-off-by: Alex Shi <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Cc: Jason Gunthorpe <[e-mail]>
Cc: Dan Williams <[e-mail]>
Cc: Vlastimil Babka <[e-mail]>
Cc: Ira Weiny <[e-mail]>
Cc: Jesper Dangaard Brouer <[e-mail]>
Cc: Andrey Ryabinin <[e-mail]>
Cc: Jann Horn <[e-mail]>
Cc: Logan Gunthorpe <[e-mail]>
Cc: Souptick Joarder <[e-mail]>
Cc: Ralph Campbell <[e-mail]>
Cc: "Tobin C. Harding" <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Oscar Salvador <[e-mail]>
Cc: Mel Gorman <[e-mail]>
Cc: Wei Yang <[e-mail]>
Cc: Johannes Weiner <[e-mail]>
Cc: Pavel Tatashin <[e-mail]>
Cc: Arun KS <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Cc: "Darrick J. Wong" <[e-mail]>
Cc: Amir Goldstein <[e-mail]>
Cc: Dave Chinner <[e-mail]>
Cc: Josef Bacik <[e-mail]>
Cc: "Kirill A. Shutemov" <[e-mail]>
Cc: "Jérôme Glisse" <[e-mail]>
Cc: Mike Kravetz <[e-mail]>
Cc: Hugh Dickins <[e-mail]>
Cc: Kirill Tkhai <[e-mail]>
Cc: Daniel Jordan <[e-mail]>
Cc: Yafang Shao <[e-mail]>
Cc: Yang Shi <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
---
 include/linux/mm_types.h | 2 +-
 include/linux/mmzone.h   | 4 ++--
 mm/filemap.c             | 4 ++--
 mm/rmap.c                | 2 +-
 mm/vmscan.c              | 6 +++---
 5 files changed, 9 insertions(+), 9 deletions(-)

Comments

Matthew Wilcox (Oracle) Aug. 20, 2019, 2 p.m. UTC | #1

On Tue, Aug 20, 2019 at 05:48:37PM +0800, Alex Shi wrote:
> @@ -159,7 +159,7 @@ static inline bool free_area_empty(struct free_area *area, int migratetype)
>  struct pglist_data;
>  
>  /*
> - * zone->lock and the zone lru_lock are two of the hottest locks in the kernel.
> + * zone->lock and the lru_lock are two of the hottest locks in the kernel.
>   * So add a wild amount of padding here to ensure that they fall into separate
>   * cachelines.  There are very few zone structures in the machine, so space
>   * consumption is not a concern here.

But after this patch series, the lru lock is no longer stored in the zone.
So this comment makes no sense.

> @@ -295,7 +295,7 @@ struct zone_reclaim_stat {
>  
>  struct lruvec {
>  	struct list_head		lists[NR_LRU_LISTS];
> -	/* move lru_lock to per lruvec for memcg */
> +	/* perf lruvec lru_lock for memcg */

What does the word 'perf' mean here?

Alex Shi Aug. 20, 2019, 2:21 p.m. UTC | #2

在 2019/8/20 下午10:00, Matthew Wilcox 写道:
> On Tue, Aug 20, 2019 at 05:48:37PM +0800, Alex Shi wrote:
>> @@ -159,7 +159,7 @@ static inline bool free_area_empty(struct free_area *area, int migratetype)
>>  struct pglist_data;
>>  
>>  /*
>> - * zone->lock and the zone lru_lock are two of the hottest locks in the kernel.
>> + * zone->lock and the lru_lock are two of the hottest locks in the kernel.
>>   * So add a wild amount of padding here to ensure that they fall into separate
>>   * cachelines.  There are very few zone structures in the machine, so space
>>   * consumption is not a concern here.
> 
> But after this patch series, the lru lock is no longer stored in the zone.
> So this comment makes no sense.

Yes, It's need reconsider here. thanks for opoint out.

> 
>> @@ -295,7 +295,7 @@ struct zone_reclaim_stat {
>>  
>>  struct lruvec {
>>  	struct list_head		lists[NR_LRU_LISTS];
>> -	/* move lru_lock to per lruvec for memcg */
>> +	/* perf lruvec lru_lock for memcg */
> 
> What does the word 'perf' mean here?

sorry for typo, could be s/perf/per/ here.

Thanks
Alex

Patch

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 6a7a1083b6fb..f9f990d8f08f 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -79,7 +79,7 @@  struct page {
 		struct {	/* Page cache and anonymous pages */
 			/**
 			 * @lru: Pageout list, eg. active_list protected by
-			 * pgdat->lru_lock.  Sometimes used as a generic list
+			 * lruvec->lru_lock.  Sometimes used as a generic list
 			 * by the page owner.
 			 */
 			struct list_head lru;
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 8d0076d084be..d2f782263e42 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -159,7 +159,7 @@  static inline bool free_area_empty(struct free_area *area, int migratetype)
 struct pglist_data;
 
 /*
- * zone->lock and the zone lru_lock are two of the hottest locks in the kernel.
+ * zone->lock and the lru_lock are two of the hottest locks in the kernel.
  * So add a wild amount of padding here to ensure that they fall into separate
  * cachelines.  There are very few zone structures in the machine, so space
  * consumption is not a concern here.
@@ -295,7 +295,7 @@  struct zone_reclaim_stat {
 
 struct lruvec {
 	struct list_head		lists[NR_LRU_LISTS];
-	/* move lru_lock to per lruvec for memcg */
+	/* perf lruvec lru_lock for memcg */
 	spinlock_t			lru_lock;
 
 	struct zone_reclaim_stat	reclaim_stat;
diff --git a/mm/filemap.c b/mm/filemap.c
index d0cf700bf201..0a604c8284f2 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -100,8 +100,8 @@ 
  *    ->swap_lock		(try_to_unmap_one)
  *    ->private_lock		(try_to_unmap_one)
  *    ->i_pages lock		(try_to_unmap_one)
- *    ->pgdat->lru_lock		(follow_page->mark_page_accessed)
- *    ->pgdat->lru_lock		(check_pte_range->isolate_lru_page)
+ *    ->lruvec->lru_lock	(follow_page->mark_page_accessed)
+ *    ->lruvec->lru_lock	(check_pte_range->isolate_lru_page)
  *    ->private_lock		(page_remove_rmap->set_page_dirty)
  *    ->i_pages lock		(page_remove_rmap->set_page_dirty)
  *    bdi.wb->list_lock		(page_remove_rmap->set_page_dirty)
diff --git a/mm/rmap.c b/mm/rmap.c
index 003377e24232..6bee4aebced6 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -27,7 +27,7 @@ 
  *         mapping->i_mmap_rwsem
  *           anon_vma->rwsem
  *             mm->page_table_lock or pte_lock
- *               pgdat->lru_lock (in mark_page_accessed, isolate_lru_page)
+ *               lruvec->lru_lock (in mark_page_accessed, isolate_lru_page)
  *               swap_lock (in swap_duplicate, swap_info_get)
  *                 mmlist_lock (in mmput, drain_mmlist and others)
  *                 mapping->private_lock (in __set_page_dirty_buffers)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index ea5c2f3f2567..1328eb182a3e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1662,7 +1662,7 @@  static __always_inline void update_lru_sizes(struct lruvec *lruvec,
 }
 
 /**
- * pgdat->lru_lock is heavily contended.  Some of the functions that
+ * lruvec->lru_lock is heavily contended.  Some of the functions that
  * shrink the lists perform better by taking out a batch of pages
  * and working on them outside the LRU lock.
  *
@@ -1864,9 +1864,9 @@  static int too_many_isolated(struct pglist_data *pgdat, int file,
  * processes, from rmap.
  *
  * If the pages are mostly unmapped, the processing is fast and it is
- * appropriate to hold zone_lru_lock across the whole operation.  But if
+ * appropriate to hold lru_lock across the whole operation.  But if
  * the pages are mapped, the processing is slow (page_referenced()) so we
- * should drop zone_lru_lock around each page.  It's impossible to balance
+ * should drop lru_lock around each page.  It's impossible to balance
  * this, so instead we remove the pages from the LRU while processing them.
  * It is safe to rely on PG_active against the non-LRU pages in here because
  * nobody will play with that bit on a non-LRU page.