[patch 051/163] mm: filemap: clear idle flag for writes

Andrew Morton
2020-08-07T06:20:00Z

From: Yang Shi <yang.shi@linux.alibaba.com>
Subject: mm: filemap: clear idle flag for writes

Since commit bbddabe2e436aa ("mm: filemap: only do access activations on
reads"), mark_page_accessed() is called for reads only. But the idle flag
is cleared by mark_page_accessed() so the idle flag won't get cleared if
the page is write accessed only.

Basically idle page tracking is used to estimate workingset size of
workload, noticeable size of workingset might be missed if the idle flag
is not maintained correctly.

It seems good enough to just clear idle flag for write operations.

Link: http://lkml.kernel.org/r/1593020612-13051-1-git-send-email-yang.shi@linux.alibaba.com
Fixes: bbddabe2e436 ("mm: filemap: only do access activations on reads")
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Reported-by: Gang Deng <gavin.dg@linux.alibaba.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

mm/filemap.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/mm/filemap.c~mm-filemap-clear-idle-flag-for-writes
+++ a/mm/filemap.c
@@ -41,6 +41,7 @@
#include <linux/delayacct.h>
#include <linux/psi.h>
#include <linux/ramfs.h>
+#include <linux/page_idle.h>
#include "internal.h"

#define CREATE_TRACE_POINTS
@@ -1689,6 +1690,11 @@ repeat:

if (fgp_flags & FGP_ACCESSED)
mark_page_accessed(page);
+ else if (fgp_flags & FGP_WRITE) {
+ /* Clear idle flag for buffer write */
+ if (page_is_idle(page))
+ clear_page_idle(page);
+ }

no_page:
if (!page && (fgp_flags & FGP_CREAT)) {
_