A rogue application can potentially create a large number of negative dentries in the system consuming most of the memory available. This can impact performance of other applications running on the system. This patchset introduces changes to the dcache subsystem to limit the number of negative dentries allowed to be created thus limiting the amount of memory that can be consumed by negative dentries. Patch 1 tracks the number of negative dentries used and disallow the creation of more when the limit is reached. Patch 2 enables /proc/sys/fs/dentry-state to report the number of negative dentries in the system. Patch 3 enables automatic pruning of negative dentries when it is close to the limit. Patch 4 prevents racing between negative dentry pruning and umount operation. Waiman Long (4): fs/dcache: Limit numbers of negative dentries fs/dcache: Report negative dentry number in dentry-state fs/dcache: Enable automatic pruning of negative dentries fs/dcache: Protect negative dentry pruning from racing with umount Documentation/admin-guide/kernel-parameters.txt | 7 + fs/dcache.c | 312 +++++++++++++++++++++++- include/linux/dcache.h | 8 +- include/linux/list_lru.h | 1 + mm/list_lru.c | 4 +- 5 files changed, 327 insertions(+), 5 deletions(-) -- 1.8.3.1
