+ zsmalloc-move-migration-destination-zspage-inuse-check.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: zsmalloc: move migration destination zspage inuse check
has been added to the -mm mm-unstable branch.  Its filename is
     zsmalloc-move-migration-destination-zspage-inuse-check.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zsmalloc-move-migration-destination-zspage-inuse-check.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: zsmalloc: move migration destination zspage inuse check
Date: Sat, 24 Jun 2023 14:12:15 +0900

Destination zspage fullness check need to be done after zs_object_copy()
because that's where source and destination zspages fullness change. 
Checking destination zspage fullness before zs_object_copy() may cause
migration to loop through source zspage sub-pages scanning for allocate
objects just to find out at the end that the destination zspage is full.

Link: https://lkml.kernel.org/r/20230624053120.643409-3-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Minchan Kim <minchan@kernel.org> 
Cc: Alexey Romanov <avromanov@sberdevices.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/zsmalloc.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/mm/zsmalloc.c~zsmalloc-move-migration-destination-zspage-inuse-check
+++ a/mm/zsmalloc.c
@@ -1620,10 +1620,6 @@ static void migrate_zspage(struct zs_poo
 			continue;
 		}
 
-		/* Stop if there is no more space */
-		if (zspage_full(class, get_zspage(d_page)))
-			break;
-
 		used_obj = handle_to_obj(handle);
 		free_obj = obj_malloc(pool, get_zspage(d_page), handle);
 		zs_object_copy(class, free_obj, used_obj);
@@ -1631,6 +1627,10 @@ static void migrate_zspage(struct zs_poo
 		record_obj(handle, free_obj);
 		obj_free(class->size, used_obj);
 
+		/* Stop if there is no more space */
+		if (zspage_full(class, get_zspage(d_page)))
+			break;
+
 		/* Stop if there are no more objects to migrate */
 		if (zspage_empty(get_zspage(s_page)))
 			break;
_

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

zsmalloc-do-not-scan-for-allocated-objects-in-empty-zspage.patch
zsmalloc-move-migration-destination-zspage-inuse-check.patch