Commit 46b76f2e authored by Miaohe Lin's avatar Miaohe Lin Committed by Linus Torvalds
Browse files

mm/zswap.c: fix two bugs in zswap_writeback_entry() 

In the ZSWAP_SWAPCACHE_FAIL and ZSWAP_SWAPCACHE_EXIST case, we forgot to
call zpool_unmap_handle() when zpool can't sleep. And we might sleep in
zswap_get_swap_cache_page() while zpool can't sleep. To fix all of these,
zpool_unmap_handle() should be done before zswap_get_swap_cache_page()
when zpool can't sleep.

Link: https://lkml.kernel.org/r/20210522092242.3233191-4-linmiaohe@huawei.com


Fixes: fc6697a8 ("mm/zswap: add the flag can_sleep_mapped")
Signed-off-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Tian Tao <tiantao6@hisilicon.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ae34af1f

mm/zswap.c

+7 −10
Original line number Diff line number Diff line
@@ -967,6 +967,13 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle) 
	spin_unlock(&tree->lock);

	BUG_ON(offset != entry->offset);



	src = (u8 *)zhdr + sizeof(struct zswap_header);

	if (!zpool_can_sleep_mapped(pool)) {

		memcpy(tmp, src, entry->length);

		src = tmp;

		zpool_unmap_handle(pool, handle);

	}



	/* try to allocate swap cache page */

	switch (zswap_get_swap_cache_page(swpentry, &page)) {

	case ZSWAP_SWAPCACHE_FAIL: /* no memory or invalidate happened */
@@ -982,17 +989,7 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle) 
	case ZSWAP_SWAPCACHE_NEW: /* page is locked */

		/* decompress */

		acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);



		dlen = PAGE_SIZE;

		src = (u8 *)zhdr + sizeof(struct zswap_header);



		if (!zpool_can_sleep_mapped(pool)) {



			memcpy(tmp, src, entry->length);

			src = tmp;



			zpool_unmap_handle(pool, handle);

		}



		mutex_lock(acomp_ctx->mutex);

		sg_init_one(&input, src, entry->length);