Description: nsfs: mark dentry with DCACHE_RCUACCESS
References:
 https://source.android.com/security/bulletin/2018-07-01
Notes:
 bwh> Introduced in 3.19 by commit e149ed2b805f "take the targets of
 bwh> /proc/*/ns/* symlinks to separate fs".
Bugs:
upstream: released (4.11-rc8) [073c516ff73557a8f7315066856c04b50383ac34]
4.9-upstream-stable: released (4.9.82) [daaa81c48402da28cc9e32ad55c48fb05e61b005]
3.16-upstream-stable: N/A "Vulnerable code not present"
sid: released (4.11.6-1)
4.9-stretch-security: released (4.9.82-1+deb9u1)
3.16-jessie-security: N/A "Vulnerable code not present"