@@ -873,7 +873,7 @@ static ssize_t mm_stat_show(struct device *dev,
zram->limit_pages << PAGE_SHIFT,
max_used << PAGE_SHIFT,
(u64)atomic64_read(&zram->stats.same_pages),
- pool_stats.pages_compacted,
+ atomic_long_read(&pool_stats.pages_compacted),
(u64)atomic64_read(&zram->stats.huge_pages));
up_read(&zram->init_lock);
@@ -36,7 +36,7 @@ enum zs_mapmode {
struct zs_pool_stats {
/* How many pages were migrated (freed) */
- unsigned long pages_compacted;
+ atomic_long_t pages_compacted;
};
struct zs_pool;
@@ -2285,11 +2285,13 @@ static unsigned long zs_can_compact(struct size_class *class)
return obj_wasted * class->pages_per_zspage;
}
-static void __zs_compact(struct zs_pool *pool, struct size_class *class)
+static unsigned long __zs_compact(struct zs_pool *pool,
+ struct size_class *class)
{
struct zs_compact_control cc;
struct zspage *src_zspage;
struct zspage *dst_zspage = NULL;
+ unsigned long pages_freed = 0;
spin_lock(&class->lock);
while ((src_zspage = isolate_zspage(class, true))) {
@@ -2319,7 +2321,7 @@ static void __zs_compact(struct zs_pool *pool, struct size_class *class)
putback_zspage(class, dst_zspage);
if (putback_zspage(class, src_zspage) == ZS_EMPTY) {
free_zspage(pool, class, src_zspage);
- pool->stats.pages_compacted += class->pages_per_zspage;
+ pages_freed += class->pages_per_zspage;
}
spin_unlock(&class->lock);
cond_resched();
@@ -2330,12 +2332,15 @@ static void __zs_compact(struct zs_pool *pool, struct size_class *class)
putback_zspage(class, src_zspage);
spin_unlock(&class->lock);
+
+ return pages_freed;
}
unsigned long zs_compact(struct zs_pool *pool)
{
int i;
struct size_class *class;
+ unsigned long pages_freed = 0;
for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) {
class = pool->size_class[i];
@@ -2343,10 +2348,11 @@ unsigned long zs_compact(struct zs_pool *pool)
continue;
if (class->index != i)
continue;
- __zs_compact(pool, class);
+ pages_freed += __zs_compact(pool, class);
}
+ atomic_long_add(pages_freed, &pool->stats.pages_compacted);
- return pool->stats.pages_compacted;
+ return pages_freed;
}
EXPORT_SYMBOL_GPL(zs_compact);
@@ -2363,13 +2369,12 @@ static unsigned long zs_shrinker_scan(struct shrinker *shrinker,
struct zs_pool *pool = container_of(shrinker, struct zs_pool,
shrinker);
- pages_freed = pool->stats.pages_compacted;
/*
* Compact classes and calculate compaction delta.
* Can run concurrently with a manually triggered
* (by user) compaction.
*/
- pages_freed = zs_compact(pool) - pages_freed;
+ pages_freed = zs_compact(pool);
return pages_freed ? pages_freed : SHRINK_STOP;
}
commit 2395928158059b8f9858365fce7713ce7fef62e4 upstream. There exists multiple path may do zram compaction concurrently. 1. auto-compaction triggered during memory reclaim 2. userspace utils write zram<id>/compaction node So, multiple threads may call zs_shrinker_scan/zs_compact concurrently. But pages_compacted is a per zsmalloc pool variable and modification of the variable is not serialized(through under class->lock). There are two issues here: 1. the pages_compacted may not equal to total number of pages freed(due to concurrently add). 2. zs_shrinker_scan may not return the correct number of pages freed(issued by current shrinker). The fix is simple: 1. account the number of pages freed in zs_compact locally. 2. use actomic variable pages_compacted to accumulate total number. Link: https://lkml.kernel.org/r/20210202122235.26885-1-wu-yan@tcl.com Fixes: 860c707dca155a56 ("zsmalloc: account the number of compacted pages") Signed-off-by: Rokudo Yan <wu-yan@tcl.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/block/zram/zram_drv.c | 2 +- include/linux/zsmalloc.h | 2 +- mm/zsmalloc.c | 17 +++++++++++------ 3 files changed, 13 insertions(+), 8 deletions(-)