On Sun, May 06, 2018 at 06:45:31PM +0100, Al Viro wrote:

On Sun, May 06, 2018 at 08:19:49PM +0300, Alexey Dobriyan wrote:

quoted

@@ -62,9 +62,9 @@ struct proc_dir_entry {
 	umode_t mode;
 	u8 namelen;
 #ifdef CONFIG_64BIT
-#define SIZEOF_PDE_INLINE_NAME	(192-139)
+#define SIZEOF_PDE_INLINE_NAME	(192-155)
 #else
-#define SIZEOF_PDE_INLINE_NAME	(128-87)
+#define SIZEOF_PDE_INLINE_NAME	(128-95)

quoted

 #endif
 	char inline_name[SIZEOF_PDE_INLINE_NAME];
 } __randomize_layout;

*UGH*

I agree. Maintaining these numbers is a pain point.
Who knew people were going to start adding fields right away.

Both to the original state and that kind of "adjustments".
Incidentally, with __bugger_layout in there these expressions
are simply wrong.

Struct randomization is exempt from maintaining sizeof as they are already
screwing cachelines and everything. But if patch works with lockdep and
randomization -- even better.

If nothing else, I would suggest turning the last one into
	char inline_name[];
in hope that layout won't get... randomized that much and
used

#ifdef CONFIG_64BIT
#define PDE_SIZE 192
#else
#define PDE_SIZE 128
#endif

union __proc_dir_entry {
	char pad[PDE_SIZE];
	struct proc_dir_entry real;
};

#define SIZEOF_PDE_INLINE_NAME (PDE_SIZE - offsetof(struct proc_dir_entry, inline_name))

for constants, adjusted sizeof and sizeof_field when creating
proc_dir_entry_cache and turned proc_root into

union __proc_dir_entry __proc_root = { .real = {
        .low_ino        = PROC_ROOT_INO,
        .namelen        = 5,
        .mode           = S_IFDIR | S_IRUGO | S_IXUGO,
        .nlink          = 2,
        .refcnt         = REFCOUNT_INIT(1),
        .proc_iops      = &proc_root_inode_operations,
        .proc_fops      = &proc_root_operations,
        .parent         = &__proc_root.real,
        .subdir         = RB_ROOT,
        .name           = __proc_root.real.inline_name,
        .inline_name    = "/proc",
}};

#define proc_root __proc_root.real
(or actually used __proc_root.real in all of a 6 places where it remains).

quoted

-	size_t state_size = PDE(inode)->state_size;
+	unsigned int state_size = PDE(inode)->state_size;

<shakes head>
You and your "size_t is evil" crusade...

[nods]

        unsigned long           flags;          /* error bits */
        unsigned long           i_state;
        unsigned long           s_blocksize;
        unsigned long           s_flags;
        unsigned long           s_iflags;       /* internal SB_I_* flags */