evie/android_kernel_oneplus_msm8998
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

zswap: don't param_set_charp while holding spinlock

Browse source 
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: c99b42c352 ("zswap: use charp for zswap param strings")
Link: http://lkml.kernel.org/r/20170126155821.4545-1-ddstreet@ieee.org
Signed-off-by: Dan Streetman <dan.streetman@canonical.com>
Reported-by: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dan Streetman 2017-02-27 14:26:53 -08:00 • committed by Greg Kroah-Hartman
parent eeca23f21c
commit c4eafbc2ba
1 changed files with 8 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

12
mm/zswap.c
View file

@ -752,18 +752,22 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
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);