From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f71.google.com (mail-pg0-f71.google.com [74.125.83.71]) by kanga.kvack.org (Postfix) with ESMTP id 7673C6B039F for ; Fri, 31 Mar 2017 11:28:53 -0400 (EDT) Received: by mail-pg0-f71.google.com with SMTP id v4so82867837pgc.20 for ; Fri, 31 Mar 2017 08:28:53 -0700 (PDT) Received: from EUR02-HE1-obe.outbound.protection.outlook.com (mail-eopbgr10092.outbound.protection.outlook.com. [40.107.1.92]) by mx.google.com with ESMTPS id a11si5536084pfl.214.2017.03.31.08.28.52 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Fri, 31 Mar 2017 08:28:52 -0700 (PDT) From: Andrey Ryabinin Subject: [PATCH] mm/zswap: fix potential deadlock in zswap_frontswap_store() Date: Fri, 31 Mar 2017 18:30:09 +0300 Message-ID: <20170331153009.11397-1-aryabinin@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: Seth Jennings , Dan Streetman Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, Andrey Ryabinin zswap_frontswap_store() is called during memory reclaim from __frontswap_store() from swap_writepage() from shrink_page_list(). This may happen in NOFS context, thus zswap shouldn't use __GFP_FS, otherwise we may renter into fs code and deadlock. zswap_frontswap_store() also shouldn't use __GFP_IO to avoid recursion into itself. zswap_frontswap_store() call zpool_malloc() with __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM, so let's use the same flags for zswap_entry_cache_alloc() as well, instead of GFP_KERNEL. Signed-off-by: Andrey Ryabinin --- mm/zswap.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/mm/zswap.c b/mm/zswap.c index eedc278..12ad7e9 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -966,6 +966,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset, struct zswap_tree *tree = zswap_trees[type]; struct zswap_entry *entry, *dupentry; struct crypto_comp *tfm; + gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM; int ret; unsigned int dlen = PAGE_SIZE, len; unsigned long handle; @@ -989,7 +990,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset, } /* allocate entry */ - entry = zswap_entry_cache_alloc(GFP_KERNEL); + entry = zswap_entry_cache_alloc(gfp); if (!entry) { zswap_reject_kmemcache_fail++; ret = -ENOMEM; @@ -1017,9 +1018,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset, /* store */ len = dlen + sizeof(struct zswap_header); - ret = zpool_malloc(entry->pool->zpool, len, - __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM, - &handle); + ret = zpool_malloc(entry->pool->zpool, len, gfp, &handle); if (ret == -ENOSPC) { zswap_reject_compress_poor++; goto put_dstmem; -- 2.10.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org