From: Barry Song <v-songbaohua@xxxxxxxx>
We used to rely on the returned -ENOSPC of zpool_malloc() to increase
reject_compress_poor. But the code wouldn't get to there after commit
744e1885922a ("crypto: scomp - fix req->dst buffer overflow") as the
new code will goto out immediately after the special compression case
happens. So there might be no longer a chance to execute zpool_malloc
now. We are incorrectly increasing zswap_reject_compress_fail instead.
Thus, we need to fix the counters handling right after compressions
return ENOSPC. This patch also centralizes the counters handling for
all of compress_poor, compress_fail and alloc_fail.
Fixes: 744e1885922a ("crypto: scomp - fix req->dst buffer overflow")
Cc: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Cc: Nhat Pham <nphamcs@xxxxxxxxx>
Cc: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
---
-v2:
* correct the fixes target according to Yosry, Chengming, Nhat's
comments;
* centralize the counters handling according to Yosry's comment
mm/zswap.c | 25 ++++++++++++-------------
1 file changed, 12 insertions(+), 13 deletions(-)
diff --git a/mm/zswap.c b/mm/zswap.c
index 350dd2fc8159..47cf07d56362 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -1498,6 +1498,7 @@ bool zswap_store(struct folio *folio)
struct zswap_tree *tree = zswap_trees[type];
struct zswap_entry *entry, *dupentry;
struct scatterlist input, output;
+ int comp_ret = 0, alloc_ret = 0;
struct crypto_acomp_ctx *acomp_ctx;
struct obj_cgroup *objcg = NULL;
struct mem_cgroup *memcg = NULL;
@@ -1508,7 +1509,6 @@ bool zswap_store(struct folio *folio)
char *buf;
u8 *src, *dst;
gfp_t gfp;
- int ret;
VM_WARN_ON_ONCE(!folio_test_locked(folio));
VM_WARN_ON_ONCE(!folio_test_swapcache(folio));
@@ -1621,28 +1621,20 @@ bool zswap_store(struct folio *folio)
* but in different threads running on different cpu, we have different
* acomp instance, so multiple threads can do (de)compression in parallel.
*/
- ret = crypto_wait_req(crypto_acomp_compress(acomp_ctx->req), &acomp_ctx->wait);
+ comp_ret = crypto_wait_req(crypto_acomp_compress(acomp_ctx->req), &acomp_ctx->wait);
dlen = acomp_ctx->req->dlen;
- if (ret) {
- zswap_reject_compress_fail++;
+ if (comp_ret)
goto put_dstmem;
- }
/* store */
zpool = zswap_find_zpool(entry);
gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;
if (zpool_malloc_support_movable(zpool))
gfp |= __GFP_HIGHMEM | __GFP_MOVABLE;
- ret = zpool_malloc(zpool, dlen, gfp, &handle);
- if (ret == -ENOSPC) {
- zswap_reject_compress_poor++;
- goto put_dstmem;
- }
- if (ret) {
- zswap_reject_alloc_fail++;
+ alloc_ret = zpool_malloc(zpool, dlen, gfp, &handle);
+ if (alloc_ret)
goto put_dstmem;
- }
buf = zpool_map_handle(zpool, handle, ZPOOL_MM_WO);
memcpy(buf, dst, dlen);
zpool_unmap_handle(zpool, handle);
@@ -1689,6 +1681,13 @@ bool zswap_store(struct folio *folio)
return true;
put_dstmem:
+ if (comp_ret == -ENOSPC || alloc_ret == -ENOSPC)
+ zswap_reject_compress_poor++;
+ else if (comp_ret)
+ zswap_reject_compress_fail++;
+ else if (alloc_ret)
+ zswap_reject_alloc_fail++;
+
mutex_unlock(&acomp_ctx->mutex);
put_pool:
zswap_pool_put(entry->pool);
--
2.34.1
