| Message ID | 20180617215732.GA24688@avx2 (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sun, Jun 17, 2018 at 2:57 PM Alexey Dobriyan <adobriyan@gmail.com> wrote: > > commit 24074a35c5c975c94cd9691ae962855333aac47f > ("proc: Make inline name size calculation automatic") > started to put PDE allocations into kmalloc-256 which is unnecessary as > ~40 character names are very rare. > > Put allocation back into kmalloc-192 cache for 64-bit non-debug builds. > > Put BUILD_BUG_ON to know when PDE size is gotten out of control. > > Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> > --- > > fs/proc/inode.c | 6 ++++-- > fs/proc/internal.h | 17 +++++++---------- > 2 files changed, 11 insertions(+), 12 deletions(-) > > --- a/fs/proc/inode.c > +++ b/fs/proc/inode.c > @@ -105,8 +105,10 @@ void __init proc_init_kmemcache(void) > kmem_cache_create("pde_opener", sizeof(struct pde_opener), 0, > SLAB_ACCOUNT|SLAB_PANIC, NULL); > proc_dir_entry_cache = kmem_cache_create_usercopy( > - "proc_dir_entry", SIZEOF_PDE_SLOT, 0, SLAB_PANIC, > - OFFSETOF_PDE_NAME, SIZEOF_PDE_INLINE_NAME, NULL); > + "proc_dir_entry", SIZEOF_PDE, 0, SLAB_PANIC, Hi Alexey, can you comment if proc_dir_entry_cache should or shouldn't have SLAB_ACCOUNT flag? Shakeel
On Thu, Jul 19, 2018 at 05:06:55PM -0700, Shakeel Butt wrote: > On Sun, Jun 17, 2018 at 2:57 PM Alexey Dobriyan <adobriyan@gmail.com> wrote: > > > > commit 24074a35c5c975c94cd9691ae962855333aac47f > > ("proc: Make inline name size calculation automatic") > > started to put PDE allocations into kmalloc-256 which is unnecessary as > > ~40 character names are very rare. > > > > Put allocation back into kmalloc-192 cache for 64-bit non-debug builds. > > > > Put BUILD_BUG_ON to know when PDE size is gotten out of control. > > > > Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> > > --- > > > > fs/proc/inode.c | 6 ++++-- > > fs/proc/internal.h | 17 +++++++---------- > > 2 files changed, 11 insertions(+), 12 deletions(-) > > > > --- a/fs/proc/inode.c > > +++ b/fs/proc/inode.c > > @@ -105,8 +105,10 @@ void __init proc_init_kmemcache(void) > > kmem_cache_create("pde_opener", sizeof(struct pde_opener), 0, > > SLAB_ACCOUNT|SLAB_PANIC, NULL); > > proc_dir_entry_cache = kmem_cache_create_usercopy( > > - "proc_dir_entry", SIZEOF_PDE_SLOT, 0, SLAB_PANIC, > > - OFFSETOF_PDE_NAME, SIZEOF_PDE_INLINE_NAME, NULL); > > + "proc_dir_entry", SIZEOF_PDE, 0, SLAB_PANIC, > > Hi Alexey, can you comment if proc_dir_entry_cache should or shouldn't > have SLAB_ACCOUNT flag? It should not (but see below): SLAB_ACCOUNT is for allocations which can be done by userspace directly: open(2) directly allocates "struct file". But /proc entries aren't like that: say, /proc/cpuinfo is created by kernel and userspace can't do anything about it. Some subsystems create /proc entries based on userspace actions and those aren't related to hardware (example: xt_hashlimit.c) but those are few so kernel doesn't bother accounting those. Or in other words: user can't mkdir(1) and touch(1) and ln(1) inside /proc at will and therefore PDEs aren't accounted.
--- a/fs/proc/inode.c +++ b/fs/proc/inode.c @@ -105,8 +105,10 @@ void __init proc_init_kmemcache(void) kmem_cache_create("pde_opener", sizeof(struct pde_opener), 0, SLAB_ACCOUNT|SLAB_PANIC, NULL); proc_dir_entry_cache = kmem_cache_create_usercopy( - "proc_dir_entry", SIZEOF_PDE_SLOT, 0, SLAB_PANIC, - OFFSETOF_PDE_NAME, SIZEOF_PDE_INLINE_NAME, NULL); + "proc_dir_entry", SIZEOF_PDE, 0, SLAB_PANIC, + offsetof(struct proc_dir_entry, inline_name), + SIZEOF_PDE_INLINE_NAME, NULL); + BUILD_BUG_ON(sizeof(struct proc_dir_entry) >= SIZEOF_PDE); } static int proc_show_options(struct seq_file *seq, struct dentry *root) --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -65,16 +65,13 @@ struct proc_dir_entry { char inline_name[]; } __randomize_layout; -#define OFFSETOF_PDE_NAME offsetof(struct proc_dir_entry, inline_name) -#define SIZEOF_PDE_SLOT \ - (OFFSETOF_PDE_NAME + 34 <= 64 ? 64 : \ - OFFSETOF_PDE_NAME + 34 <= 128 ? 128 : \ - OFFSETOF_PDE_NAME + 34 <= 192 ? 192 : \ - OFFSETOF_PDE_NAME + 34 <= 256 ? 256 : \ - OFFSETOF_PDE_NAME + 34 <= 512 ? 512 : \ - 0) - -#define SIZEOF_PDE_INLINE_NAME (SIZEOF_PDE_SLOT - OFFSETOF_PDE_NAME) +#ifdef CONFIG_64BIT +#define SIZEOF_PDE (sizeof(spinlock_t) <= 4 ? 192 : 256) +#else +#define SIZEOF_PDE (sizeof(spinlock_t) <= 4 ? 128 : 192) +#endif + +#define SIZEOF_PDE_INLINE_NAME (SIZEOF_PDE - sizeof(struct proc_dir_entry)) extern struct kmem_cache *proc_dir_entry_cache; void pde_free(struct proc_dir_entry *pde);
commit 24074a35c5c975c94cd9691ae962855333aac47f ("proc: Make inline name size calculation automatic") started to put PDE allocations into kmalloc-256 which is unnecessary as ~40 character names are very rare. Put allocation back into kmalloc-192 cache for 64-bit non-debug builds. Put BUILD_BUG_ON to know when PDE size is gotten out of control. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> --- fs/proc/inode.c | 6 ++++-- fs/proc/internal.h | 17 +++++++---------- 2 files changed, 11 insertions(+), 12 deletions(-)