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authorHuang Ying2020-04-06 20:04:41 -0700
committerLinus Torvalds2020-04-07 10:43:38 -0700
commit9de4f22a60f731943f050f4448bf2933ed3fa70b (patch)
treea748811bb7451c957caf32df4cbd67fa28e1013b /include
parent7a9547fd4ebc5df52245e1df8a2e0bb481f20a92 (diff)
mm: code cleanup for MADV_FREE
Some comments for MADV_FREE is revised and added to help people understand the MADV_FREE code, especially the page flag, PG_swapbacked. This makes page_is_file_cache() isn't consistent with its comments. So the function is renamed to page_is_file_lru() to make them consistent again. All these are put in one patch as one logical change. Suggested-by: David Hildenbrand <david@redhat.com> Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: David Rientjes <rientjes@google.com> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@kernel.org> Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/20200317100342.2730705-1-ying.huang@intel.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/mm_inline.h15
-rw-r--r--include/linux/page-flags.h5
-rw-r--r--include/trace/events/vmscan.h2
3 files changed, 14 insertions, 8 deletions
diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
index 6f2fef7b0784..219bef41d87c 100644
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -6,19 +6,20 @@
#include <linux/swap.h>
/**
- * page_is_file_cache - should the page be on a file LRU or anon LRU?
+ * page_is_file_lru - should the page be on a file LRU or anon LRU?
* @page: the page to test
*
- * Returns 1 if @page is page cache page backed by a regular filesystem,
- * or 0 if @page is anonymous, tmpfs or otherwise ram or swap backed.
- * Used by functions that manipulate the LRU lists, to sort a page
- * onto the right LRU list.
+ * Returns 1 if @page is a regular filesystem backed page cache page or a lazily
+ * freed anonymous page (e.g. via MADV_FREE). Returns 0 if @page is a normal
+ * anonymous page, a tmpfs page or otherwise ram or swap backed page. Used by
+ * functions that manipulate the LRU lists, to sort a page onto the right LRU
+ * list.
*
* We would like to get this info without a page flag, but the state
* needs to survive until the page is last deleted from the LRU, which
* could be as far down as __page_cache_release.
*/
-static inline int page_is_file_cache(struct page *page)
+static inline int page_is_file_lru(struct page *page)
{
return !PageSwapBacked(page);
}
@@ -75,7 +76,7 @@ static __always_inline void del_page_from_lru_list(struct page *page,
*/
static inline enum lru_list page_lru_base_type(struct page *page)
{
- if (page_is_file_cache(page))
+ if (page_is_file_lru(page))
return LRU_INACTIVE_FILE;
return LRU_INACTIVE_ANON;
}
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 77de28bfefb0..acf7988fd640 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -63,6 +63,11 @@
* page_waitqueue(page) is a wait queue of all tasks waiting for the page
* to become unlocked.
*
+ * PG_swapbacked is set when a page uses swap as a backing storage. This are
+ * usually PageAnon or shmem pages but please note that even anonymous pages
+ * might lose their PG_swapbacked flag when they simply can be dropped (e.g. as
+ * a result of MADV_FREE).
+ *
* PG_uptodate tells whether the page's contents is valid. When a read
* completes, the page becomes uptodate, unless a disk I/O error happened.
*
diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
index a5ab2973e8dc..74bb594ccb25 100644
--- a/include/trace/events/vmscan.h
+++ b/include/trace/events/vmscan.h
@@ -323,7 +323,7 @@ TRACE_EVENT(mm_vmscan_writepage,
TP_fast_assign(
__entry->pfn = page_to_pfn(page);
__entry->reclaim_flags = trace_reclaim_flags(
- page_is_file_cache(page));
+ page_is_file_lru(page));
),
TP_printk("page=%p pfn=%lu flags=%s",