* Re: [PATCH] proc: Make inline name size calculation automatic @ 2018-06-14 20:09 Alexey Dobriyan 2018-06-14 20:30 ` David Howells 0 siblings, 1 reply; 6+ messages in thread From: Alexey Dobriyan @ 2018-06-14 20:09 UTC (permalink / raw) To: dhowells; +Cc: viro, linux-fsdevel, linux-kernel > Require a minimum inline name size of 33+1 to allow for names that look > like two hex numbers with a dash between. Hi, David. Why 34? /proc will fallback to separate allocation for name anyway. I sent nearly identical patch earlier. https://marc.info/?l=linux-kernel&m=152667374404900&w=4 If you compare, the differences are: * no BUILD_BUG_ON, * 64 bytes is too litle even on 32-bit, * 512 bytes is probably too much even on 64-bit. > - .name = proc_root.inline_name, > - .inline_name = "/proc", > + .name = "/proc", This will "uninline" 5 bytes wasting space. ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] proc: Make inline name size calculation automatic 2018-06-14 20:09 [PATCH] proc: Make inline name size calculation automatic Alexey Dobriyan @ 2018-06-14 20:30 ` David Howells 2018-06-15 17:15 ` Alexey Dobriyan 2018-06-17 21:57 ` [PATCH] proc: fixup PDE allocation bloat Alexey Dobriyan 0 siblings, 2 replies; 6+ messages in thread From: David Howells @ 2018-06-14 20:30 UTC (permalink / raw) To: Alexey Dobriyan; +Cc: dhowells, viro, linux-fsdevel, linux-kernel Alexey Dobriyan <adobriyan@gmail.com> wrote: > > Require a minimum inline name size of 33+1 to allow for names that look > > like two hex numbers with a dash between. > > Why 34? /proc will fallback to separate allocation for name anyway. See above comment. I ran find on /proc and there were a bunch of files whose names were "<hex>-<hex>". Allow for 16-char hex addresses and add a NUL char to that and you get 34. David ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] proc: Make inline name size calculation automatic 2018-06-14 20:30 ` David Howells @ 2018-06-15 17:15 ` Alexey Dobriyan 2018-06-17 21:57 ` [PATCH] proc: fixup PDE allocation bloat Alexey Dobriyan 1 sibling, 0 replies; 6+ messages in thread From: Alexey Dobriyan @ 2018-06-15 17:15 UTC (permalink / raw) To: David Howells; +Cc: viro, linux-fsdevel, linux-kernel On Thu, Jun 14, 2018 at 09:30:42PM +0100, David Howells wrote: > Alexey Dobriyan <adobriyan@gmail.com> wrote: > > > > Require a minimum inline name size of 33+1 to allow for names that look > > > like two hex numbers with a dash between. > > > > Why 34? /proc will fallback to separate allocation for name anyway. > > See above comment. I ran find on /proc and there were a bunch of files whose > names were "<hex>-<hex>". Allow for 16-char hex addresses and add a NUL char > to that and you get 34. Those must be /proc/*/map_files symlinks. If that's the case, they don't have PDEs allocated. ^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH] proc: fixup PDE allocation bloat 2018-06-14 20:30 ` David Howells 2018-06-15 17:15 ` Alexey Dobriyan @ 2018-06-17 21:57 ` Alexey Dobriyan 2018-07-20 0:06 ` Shakeel Butt 1 sibling, 1 reply; 6+ messages in thread From: Alexey Dobriyan @ 2018-06-17 21:57 UTC (permalink / raw) To: dhowells, viro, akpm; +Cc: linux-fsdevel, linux-kernel 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, + 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); ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] proc: fixup PDE allocation bloat 2018-06-17 21:57 ` [PATCH] proc: fixup PDE allocation bloat Alexey Dobriyan @ 2018-07-20 0:06 ` Shakeel Butt 2018-08-17 13:28 ` Alexey Dobriyan 0 siblings, 1 reply; 6+ messages in thread From: Shakeel Butt @ 2018-07-20 0:06 UTC (permalink / raw) To: adobriyan; +Cc: dhowells, Alexander Viro, Andrew Morton, linux-fsdevel, LKML 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 ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] proc: fixup PDE allocation bloat 2018-07-20 0:06 ` Shakeel Butt @ 2018-08-17 13:28 ` Alexey Dobriyan 0 siblings, 0 replies; 6+ messages in thread From: Alexey Dobriyan @ 2018-08-17 13:28 UTC (permalink / raw) To: Shakeel Butt; +Cc: dhowells, Alexander Viro, Andrew Morton, linux-fsdevel, LKML 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. ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2018-08-17 16:32 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2018-06-14 20:09 [PATCH] proc: Make inline name size calculation automatic Alexey Dobriyan 2018-06-14 20:30 ` David Howells 2018-06-15 17:15 ` Alexey Dobriyan 2018-06-17 21:57 ` [PATCH] proc: fixup PDE allocation bloat Alexey Dobriyan 2018-07-20 0:06 ` Shakeel Butt 2018-08-17 13:28 ` Alexey Dobriyan
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