Since:
"42c06a0e8ebe mm: kill frontswap"
we no longer have a counter to tracks the number of zswap store
failures. This makes it hard to investigate and monitor for zswap
issues.
This patch adds a global and a per-cgroup zswap store failure counter,
as well as a dedicated debugfs counter for compression algorithm failure
(which can happen for e.g when random data are passed to zswap).
Signed-off-by: Nhat Pham <nphamcs@xxxxxxxxx>
---
include/linux/vm_event_item.h | 1 +
mm/memcontrol.c | 1 +
mm/vmstat.c | 1 +
mm/zswap.c | 18 ++++++++++++++----
4 files changed, 17 insertions(+), 4 deletions(-)
diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index 8abfa1240040..7b2b117b193d 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -145,6 +145,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
#ifdef CONFIG_ZSWAP
ZSWPIN,
ZSWPOUT,
+ ZSWPOUT_FAIL,
#endif
#ifdef CONFIG_X86
DIRECT_MAP_LEVEL2_SPLIT,
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 61c0c46c2d62..0e247e72a379 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -593,6 +593,7 @@ static const unsigned int memcg_vm_event_stat[] = {
#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP)
ZSWPIN,
ZSWPOUT,
+ ZSWPOUT_FAIL,
#endif
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
THP_FAULT_ALLOC,
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 359460deb377..85cc79449355 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1401,6 +1401,7 @@ const char * const vmstat_text[] = {
#ifdef CONFIG_ZSWAP
"zswpin",
"zswpout",
+ "zswpout_fail",
#endif
#ifdef CONFIG_X86
"direct_map_level2_splits",
diff --git a/mm/zswap.c b/mm/zswap.c
index 37d2b1cb2ecb..38e6620f8b58 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -61,6 +61,8 @@ static u64 zswap_pool_limit_hit;
static u64 zswap_written_back_pages;
/* Store failed due to a reclaim failure after pool limit was reached */
static u64 zswap_reject_reclaim_fail;
+/* Store failed due to compression algorithm failure */
+static u64 zswap_reject_compress_fail;
/* Compressed page was too big for the allocator to (optimally) store */
static u64 zswap_reject_compress_poor;
/* Store failed because underlying allocator could not get memory */
@@ -1213,10 +1215,10 @@ bool zswap_store(struct folio *folio)
/* Large folios aren't supported */
if (folio_test_large(folio))
- return false;
+ goto out_reject;
if (!zswap_enabled || !tree)
- return false;
+ goto out_reject;
/*
* If this is a duplicate, it must be removed before attempting to store
@@ -1309,8 +1311,10 @@ bool zswap_store(struct folio *folio)
ret = crypto_wait_req(crypto_acomp_compress(acomp_ctx->req), &acomp_ctx->wait);
dlen = acomp_ctx->req->dlen;
- if (ret)
+ if (ret) {
+ zswap_reject_compress_fail++;
goto put_dstmem;
+ }
/* store */
zpool = zswap_find_zpool(entry);
@@ -1377,8 +1381,12 @@ bool zswap_store(struct folio *folio)
freepage:
zswap_entry_cache_free(entry);
reject:
- if (objcg)
+ if (objcg) {
+ count_objcg_event(objcg, ZSWPOUT_FAIL);
obj_cgroup_put(objcg);
+ }
+out_reject:
+ count_vm_event(ZSWPOUT_FAIL);
return false;
shrink:
@@ -1550,6 +1558,8 @@ static int zswap_debugfs_init(void)
zswap_debugfs_root, &zswap_reject_alloc_fail);
debugfs_create_u64("reject_kmemcache_fail", 0444,
zswap_debugfs_root, &zswap_reject_kmemcache_fail);
+ debugfs_create_u64("reject_compress_fail", 0444,
+ zswap_debugfs_root, &zswap_reject_compress_fail);
debugfs_create_u64("reject_compress_poor", 0444,
zswap_debugfs_root, &zswap_reject_compress_poor);
debugfs_create_u64("written_back_pages", 0444,
--
2.34.1
