diff options
authorDave Hansen <>2021-05-04 18:36:04 -0700
committerLinus Torvalds <>2021-05-05 11:27:23 -0700
commit202e35db5e719ee8af6028183403f475e243f82d (patch)
parentb6676de8d7b48724d4cd3a3742c62fa525baa904 (diff)
mm/vmscan: replace implicit RECLAIM_ZONE checks with explicit checks
RECLAIM_ZONE was assumed to be unused because it was never explicitly used in the kernel. However, there were a number of places where it was checked implicitly by checking 'node_reclaim_mode' for a zero value. These zero checks are not great because it is not obvious what a zero mode *means* in the code. Replace them with a helper which makes it more obvious: node_reclaim_enabled(). This helper also provides a handy place to explicitly check the RECLAIM_ZONE bit itself. Check it explicitly there to make it more obvious where the bit can affect behavior. This should have no functional impact. Link: Signed-off-by: Dave Hansen <> Reviewed-by: Ben Widawsky <> Reviewed-by: Oscar Salvador <> Acked-by: Christoph Lameter <> Acked-by: David Rientjes <> Cc: Alex Shi <> Cc: "Tobin C. Harding" <> Cc: Huang Ying <> Cc: Dan Williams <> Cc: Qian Cai <> Cc: Daniel Wagner <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
3 files changed, 9 insertions, 2 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 4cc6ec3bf0ab..42191da1bdc9 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -12,6 +12,7 @@
#include <linux/fs.h>
#include <linux/atomic.h>
#include <linux/page-flags.h>
+#include <uapi/linux/mempolicy.h>
#include <asm/page.h>
struct notifier_block;
@@ -378,6 +379,12 @@ extern int sysctl_min_slab_ratio;
#define node_reclaim_mode 0
+static inline bool node_reclaim_enabled(void)
+ /* Is any node_reclaim_mode bit set? */
+ return node_reclaim_mode & (RECLAIM_ZONE|RECLAIM_WRITE|RECLAIM_UNMAP);
extern void check_move_unevictable_pages(struct pagevec *pvec);
extern int kswapd_run(int nid);
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index a03569eda183..ea74da3232ab 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -809,7 +809,7 @@ static bool khugepaged_scan_abort(int nid)
* If node_reclaim_mode is disabled, then no extra effort is made to
* allocate memory locally.
- if (!node_reclaim_mode)
+ if (!node_reclaim_enabled())
return false;
/* If there is a count for this node already, it must be acceptable */
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 80fa6e0f9ed9..19cdd8a829dc 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3968,7 +3968,7 @@ retry:
if (alloc_flags & ALLOC_NO_WATERMARKS)
goto try_this_zone;
- if (node_reclaim_mode == 0 ||
+ if (!node_reclaim_enabled() ||
!zone_allows_reclaim(ac->preferred_zoneref->zone, zone))