+ mm-zswap-remove-the-memcpy-if-acomp-is-not-sleepable.patch added to mm-unstable branch

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

The patch titled
     Subject: mm/zswap: remove the memcpy if acomp is not sleepable
has been added to the -mm mm-unstable branch.  Its filename is
     mm-zswap-remove-the-memcpy-if-acomp-is-not-sleepable.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-zswap-remove-the-memcpy-if-acomp-is-not-sleepable.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@oppo.com>
Subject: mm/zswap: remove the memcpy if acomp is not sleepable
Date: Sat, 17 Feb 2024 17:51:01 +1300

Most compressors are actually CPU-based and won't sleep during compression
and decompression.  We should remove the redundant memcpy for them.

Link: https://lkml.kernel.org/r/20240217045102.55339-3-21cnbao@gmail.com
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/zswap.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/mm/zswap.c~mm-zswap-remove-the-memcpy-if-acomp-is-not-sleepable
+++ a/mm/zswap.c
@@ -162,6 +162,7 @@ struct crypto_acomp_ctx {
 	struct crypto_wait wait;
 	u8 *buffer;
 	struct mutex mutex;
+	bool is_sleepable;
 };
 
 /*
@@ -973,6 +974,7 @@ static int zswap_cpu_comp_prepare(unsign
 		goto acomp_fail;
 	}
 	acomp_ctx->acomp = acomp;
+	acomp_ctx->is_sleepable = acomp_is_sleepable(acomp);
 
 	req = acomp_request_alloc(acomp_ctx->acomp);
 	if (!req) {
@@ -1101,7 +1103,7 @@ static void zswap_decompress(struct zswa
 	mutex_lock(&acomp_ctx->mutex);
 
 	src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO);
-	if (!zpool_can_sleep_mapped(zpool)) {
+	if (acomp_ctx->is_sleepable && !zpool_can_sleep_mapped(zpool)) {
 		memcpy(acomp_ctx->buffer, src, entry->length);
 		src = acomp_ctx->buffer;
 		zpool_unmap_handle(zpool, entry->handle);
@@ -1115,7 +1117,7 @@ static void zswap_decompress(struct zswa
 	BUG_ON(acomp_ctx->req->dlen != PAGE_SIZE);
 	mutex_unlock(&acomp_ctx->mutex);
 
-	if (zpool_can_sleep_mapped(zpool))
+	if (!acomp_ctx->is_sleepable || zpool_can_sleep_mapped(zpool))
 		zpool_unmap_handle(zpool, entry->handle);
 }
 
_

Patches currently in -mm which might be from v-songbaohua@oppo.com are

zram-do-not-allocate-physically-contiguous-strm-buffers.patch
crypto-introduce-acomp_is_sleepable-to-expose-if-comp-drivers-might-sleep.patch
mm-zswap-remove-the-memcpy-if-acomp-is-not-sleepable.patch
crypto-scompress-remove-memcpy-if-sg_nents-is-1.patch