fs, file table: reinit files_stat.max_files after deferred memory initialisation

Dave Hansen reported the following;

	My laptop has been behaving strangely with 4.2-rc2.  Once I log
	in to my X session, I start getting all kinds of strange errors
	from applications and see this in my dmesg:

        	VFS: file-max limit 8192 reached

The problem is that the file-max is calculated before memory is fully
initialised and miscalculates how much memory the kernel is using.  This
patch recalculates file-max after deferred memory initialisation.  Note
that using memory hotplug infrastructure would not have avoided this
problem as the value is not recalculated after memory hot-add.

4.1:             files_stat.max_files = 6582781
4.2-rc2:         files_stat.max_files = 8192
4.2-rc2 patched: files_stat.max_files = 6562467

Small differences with the patch applied and 4.1 but not enough to matter.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reported-by: Dave Hansen <dave.hansen@intel.com>
Cc: Nicolai Stange <nicstange@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Alex Ng <alexng@microsoft.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index cc008c338f5a..84b783f277f7 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -55,7 +55,8 @@ struct vm_fault;
 
 extern void __init inode_init(void);
 extern void __init inode_init_early(void);
-extern void __init files_init(unsigned long);
+extern void __init files_init(void);
+extern void __init files_maxfiles_init(void);
 
 extern struct files_stat_struct files_stat;
 extern unsigned long get_max_files(void);
@@ -2245,7 +2246,7 @@ extern int ioctl_preallocate(struct file *filp, void __user *argp);
 
 /* fs/dcache.c */
 extern void __init vfs_caches_init_early(void);
-extern void __init vfs_caches_init(unsigned long);
+extern void __init vfs_caches_init(void);
 
 extern struct kmem_cache *names_cachep;