The patch titled
Subject: mm: zswap: increase reject_compress_poor but not reject_compress_fail if compression returns ENOSPC
has been added to the -mm mm-unstable branch. Its filename is
mm-zswap-increase-reject_compress_poor-but-not-reject_compress_fail-if-compression-returns-enospc.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-zswap-increase-reject_compress_poor-but-not-reject_compress_fail-if-compression-returns-enospc.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: Barry Song <v-songbaohua@xxxxxxxx>
Subject: mm: zswap: increase reject_compress_poor but not reject_compress_fail if compression returns ENOSPC
Date: Tue, 20 Feb 2024 10:19:35 +1300
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.
Link: https://lkml.kernel.org/r/20240219211935.72394-1-21cnbao@xxxxxxxxx
Fixes: 744e1885922a ("crypto: scomp - fix req->dst buffer overflow")
Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
Cc: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Reviewed-by: Nhat Pham <nphamcs@xxxxxxxxx>
Acked-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Reviewed-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/zswap.c | 27 +++++++++++++--------------
1 file changed, 13 insertions(+), 14 deletions(-)
--- a/mm/zswap.c~mm-zswap-increase-reject_compress_poor-but-not-reject_compress_fail-if-compression-returns-enospc
+++ a/mm/zswap.c
@@ -1021,12 +1021,12 @@ static bool zswap_compress(struct folio
{
struct crypto_acomp_ctx *acomp_ctx;
struct scatterlist input, output;
+ int comp_ret = 0, alloc_ret = 0;
unsigned int dlen = PAGE_SIZE;
unsigned long handle;
struct zpool *zpool;
char *buf;
gfp_t gfp;
- int ret;
u8 *dst;
acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
@@ -1057,26 +1057,18 @@ static bool zswap_compress(struct 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 unlock;
- }
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 unlock;
- }
- if (ret) {
- zswap_reject_alloc_fail++;
+ alloc_ret = zpool_malloc(zpool, dlen, gfp, &handle);
+ if (alloc_ret)
goto unlock;
- }
buf = zpool_map_handle(zpool, handle, ZPOOL_MM_WO);
memcpy(buf, dst, dlen);
@@ -1086,8 +1078,15 @@ static bool zswap_compress(struct folio
entry->length = dlen;
unlock:
+ 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);
- return ret == 0;
+ return comp_ret == 0 && alloc_ret == 0;
}
static void zswap_decompress(struct zswap_entry *entry, struct page *page)
_
Patches currently in -mm which might be from v-songbaohua@xxxxxxxx are
zram-do-not-allocate-physically-contiguous-strm-buffers.patch
mm-zswap-increase-reject_compress_poor-but-not-reject_compress_fail-if-compression-returns-enospc.patch
