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SubjectRe: [PATCH] fs, mm: account filp and names caches to kmemcg
On Thu 05-10-17 15:21:44, Shakeel Butt wrote:
> The allocations from filp and names kmem caches can be directly
> triggered by user space applications. A buggy application can
> consume a significant amount of unaccounted system memory. Though
> we have not noticed such buggy applications in our production
> but upon close inspection, we found that a lot of machines spend
> very significant amount of memory on these caches. So, these
> caches should be accounted to kmemcg.
>
> Signed-off-by: Shakeel Butt <shakeelb@google.com>
> ---
> fs/dcache.c | 2 +-
> fs/file_table.c | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/dcache.c b/fs/dcache.c
> index f90141387f01..fb3449161063 100644
> --- a/fs/dcache.c
> +++ b/fs/dcache.c
> @@ -3642,7 +3642,7 @@ void __init vfs_caches_init_early(void)
> void __init vfs_caches_init(void)
> {
> names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0,
> - SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
> + SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL);

I might be wrong but isn't name cache only holding temporary objects
used for path resolution which are not stored anywhere?

>
> dcache_init();
> inode_init();
> diff --git a/fs/file_table.c b/fs/file_table.c
> index 61517f57f8ef..567888cdf7d3 100644
> --- a/fs/file_table.c
> +++ b/fs/file_table.c
> @@ -312,7 +312,7 @@ void put_filp(struct file *file)
> void __init files_init(void)
> {
> filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0,
> - SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
> + SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT, NULL);
> percpu_counter_init(&nr_files, 0, GFP_KERNEL);
> }

Don't we have a limit for the maximum number of open files?

--
Michal Hocko
SUSE Labs

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