From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:57154 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932421AbeAKOFK (ORCPT ); Thu, 11 Jan 2018 09:05:10 -0500 Subject: Patch "zswap: don't param_set_charp while holding spinlock" has been added to the 4.9-stable tree To: ddstreet@ieee.org, akpm@linux-foundation.org, dan.streetman@canonical.com, gregkh@linuxfoundation.org, mhocko@kernel.org, minchan@kernel.org, sergey.senozhatsky.work@gmail.com, torvalds@linux-foundation.org, vbabka@suse.cz Cc: , From: Date: Thu, 11 Jan 2018 15:05:10 +0100 Message-ID: <151567951051240@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled zswap: don't param_set_charp while holding spinlock to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: zswap-don-t-param_set_charp-while-holding-spinlock.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From fd5bb66cd934987e49557455b6497fc006521940 Mon Sep 17 00:00:00 2001 From: Dan Streetman Date: Mon, 27 Feb 2017 14:26:53 -0800 Subject: zswap: don't param_set_charp while holding spinlock From: Dan Streetman commit fd5bb66cd934987e49557455b6497fc006521940 upstream. Change the zpool/compressor param callback function to release the zswap_pools_lock spinlock before calling param_set_charp, since that function may sleep when it calls kmalloc with GFP_KERNEL. While this problem has existed for a while, I wasn't able to trigger it using a tight loop changing either/both the zpool and compressor params; I think it's very unlikely to be an issue on the stable kernels, especially since most zswap users will change the compressor and/or zpool from sysfs only one time each boot - or zero times, if they add the params to the kernel boot. Fixes: c99b42c3529e ("zswap: use charp for zswap param strings") Link: http://lkml.kernel.org/r/20170126155821.4545-1-ddstreet@ieee.org Signed-off-by: Dan Streetman Reported-by: Sergey Senozhatsky Cc: Michal Hocko Cc: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Vlastimil Babka Signed-off-by: Greg Kroah-Hartman --- mm/zswap.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) --- a/mm/zswap.c +++ b/mm/zswap.c @@ -752,18 +752,22 @@ static int __zswap_param_set(const char pool = zswap_pool_find_get(type, compressor); if (pool) { zswap_pool_debug("using existing", pool); + WARN_ON(pool == zswap_pool_current()); list_del_rcu(&pool->list); - } else { - spin_unlock(&zswap_pools_lock); - pool = zswap_pool_create(type, compressor); - spin_lock(&zswap_pools_lock); } + spin_unlock(&zswap_pools_lock); + + if (!pool) + pool = zswap_pool_create(type, compressor); + if (pool) ret = param_set_charp(s, kp); else ret = -EINVAL; + spin_lock(&zswap_pools_lock); + if (!ret) { put_pool = zswap_pool_current(); list_add_rcu(&pool->list, &zswap_pools); Patches currently in stable-queue which might be from ddstreet@ieee.org are queue-4.9/zswap-don-t-param_set_charp-while-holding-spinlock.patch