From 9c3760eb80880f3e02546e0a2ef479e1454986b3 Mon Sep 17 00:00:00 2001 From: Yu Zhao Date: Wed, 31 Jan 2018 16:19:59 -0800 Subject: zswap: only save zswap header when necessary We waste sizeof(swp_entry_t) for zswap header when using zsmalloc as zpool driver because zsmalloc doesn't support eviction. Add zpool_evictable() to detect if zpool is potentially evictable, and use it in zswap to avoid waste memory for zswap header. [yuzhao@google.com: The zpool->" prefix is a result of copy & paste] Link: http://lkml.kernel.org/r/20180110225626.110330-1-yuzhao@google.com Link: http://lkml.kernel.org/r/20180110224741.83751-1-yuzhao@google.com Signed-off-by: Yu Zhao Acked-by: Dan Streetman Reviewed-by: Sergey Senozhatsky Cc: Seth Jennings Cc: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/zswap.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) (limited to 'mm/zswap.c') diff --git a/mm/zswap.c b/mm/zswap.c index 1133b4ceb72e..c004aa4fd3f4 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -1001,11 +1001,11 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset, struct zswap_entry *entry, *dupentry; struct crypto_comp *tfm; int ret; - unsigned int dlen = PAGE_SIZE, len; + unsigned int hlen, dlen = PAGE_SIZE; unsigned long handle, value; char *buf; u8 *src, *dst; - struct zswap_header *zhdr; + struct zswap_header zhdr = { .swpentry = swp_entry(type, offset) }; if (!zswap_enabled || !tree) { ret = -ENODEV; @@ -1063,8 +1063,8 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset, } /* store */ - len = dlen + sizeof(struct zswap_header); - ret = zpool_malloc(entry->pool->zpool, len, + hlen = zpool_evictable(entry->pool->zpool) ? sizeof(zhdr) : 0; + ret = zpool_malloc(entry->pool->zpool, hlen + dlen, __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM, &handle); if (ret == -ENOSPC) { @@ -1075,10 +1075,9 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset, zswap_reject_alloc_fail++; goto put_dstmem; } - zhdr = zpool_map_handle(entry->pool->zpool, handle, ZPOOL_MM_RW); - zhdr->swpentry = swp_entry(type, offset); - buf = (u8 *)(zhdr + 1); - memcpy(buf, dst, dlen); + buf = zpool_map_handle(entry->pool->zpool, handle, ZPOOL_MM_RW); + memcpy(buf, &zhdr, hlen); + memcpy(buf + hlen, dst, dlen); zpool_unmap_handle(entry->pool->zpool, handle); put_cpu_var(zswap_dstmem); @@ -1149,8 +1148,9 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset, /* decompress */ dlen = PAGE_SIZE; - src = (u8 *)zpool_map_handle(entry->pool->zpool, entry->handle, - ZPOOL_MM_RO) + sizeof(struct zswap_header); + src = zpool_map_handle(entry->pool->zpool, entry->handle, ZPOOL_MM_RO); + if (zpool_evictable(entry->pool->zpool)) + src += sizeof(struct zswap_header); dst = kmap_atomic(page); tfm = *get_cpu_ptr(entry->pool->tfm); ret = crypto_comp_decompress(tfm, src, entry->length, dst, &dlen); -- cgit