+ zram-do-not-mark-idle-slots-that-cannot-be-idle.patch added to mm-unstable branch

+ zram-do-not-mark-idle-slots-that-cannot-be-idle.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: zram: do not mark idle slots that cannot be idle
has been added to the -mm mm-unstable branch.  Its filename is
     zram-do-not-mark-idle-slots-that-cannot-be-idle.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zram-do-not-mark-idle-slots-that-cannot-be-idle.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Sergey Senozhatsky <senozhatsky@chromium.org>
Subject: zram: do not mark idle slots that cannot be idle
Date: Tue, 17 Sep 2024 11:09:10 +0900

ZRAM_SAME slots cannot be post-processed (writeback or recompress) so do
not mark them ZRAM_IDLE.  Same with ZRAM_WB slots, they cannot be
ZRAM_IDLE because they are not in zsmalloc pool anymore.

Link: https://lkml.kernel.org/r/20240917021020.883356-6-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/block/zram/zram_drv.c |   25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

--- a/drivers/block/zram/zram_drv.c~zram-do-not-mark-idle-slots-that-cannot-be-idle
+++ a/drivers/block/zram/zram_drv.c
@@ -392,17 +392,28 @@ static void mark_idle(struct zram *zram,
 		/*
 		 * Do not mark ZRAM_UNDER_WB slot as ZRAM_IDLE to close race.
 		 * See the comment in writeback_store.
+		 *
+		 * Also do not mark ZRAM_SAME slots as ZRAM_IDLE, because no
+		 * post-processing (recompress, writeback) happens to the
+		 * ZRAM_SAME slot.
+		 *
+		 * And ZRAM_WB slots simply cannot be ZRAM_IDLE.
 		 */
 		zram_slot_lock(zram, index);
-		if (zram_allocated(zram, index) &&
-				!zram_test_flag(zram, index, ZRAM_UNDER_WB)) {
+		if (!zram_allocated(zram, index) ||
+		    zram_test_flag(zram, index, ZRAM_WB) ||
+		    zram_test_flag(zram, index, ZRAM_UNDER_WB) ||
+		    zram_test_flag(zram, index, ZRAM_SAME)) {
+			zram_slot_unlock(zram, index);
+			continue;
+		}
+
 #ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME
-			is_idle = !cutoff || ktime_after(cutoff,
-							 zram->table[index].ac_time);
+		is_idle = !cutoff ||
+			ktime_after(cutoff, zram->table[index].ac_time);
 #endif
-			if (is_idle)
-				zram_set_flag(zram, index, ZRAM_IDLE);
-		}
+		if (is_idle)
+			zram_set_flag(zram, index, ZRAM_IDLE);
 		zram_slot_unlock(zram, index);
 	}
 }
_

Patches currently in -mm which might be from senozhatsky@chromium.org are

zram-introduce-zram_pp_slot-flag.patch
zram-permit-only-one-post-processing-operation-at-a-time.patch
zram-rework-recompress-target-selection-strategy.patch
zram-rework-writeback-target-selection-strategy.patch
zram-do-not-mark-idle-slots-that-cannot-be-idle.patch
zram-reshuffle-zram_free_page-flags-operations.patch
zram-remove-under_wb-and-simplify-writeback.patch