Message-ID: <55A530A3.2080301@intel.com>
Date: Tue, 14 Jul 2015 08:54:11 -0700
From: Dave Hansen <dave.hansen@intel.com>
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To: Mel Gorman <mgorman@suse.de>, Andrew Morton <akpm@linux-foundation.org>
CC: Nathan Zimmer <nzimmer@sgi.com>, Waiman Long <waiman.long@hp.com>,
        Scott Norton <scott.norton@hp.com>,
        Daniel J Blueman <daniel@numascale.com>, Linux-MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>, Al Viro <viro@zeniv.linux.org.uk>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: 4.2-rc2: hitting "file-max limit 8192 reached"
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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

Could this be from CONFIG_DEFERRED_STRUCT_PAGE_INIT=y?  files_init()
seems top be sizing files_stat.max_files from memory sizes.

vfs_caches_init() uses nr_free_pages() to figure out what the "current
kernel size" is in early boot.  *But* since we have not freed most of
our memory, nr_free_pages() is low and makes us calculate the reserve as
if the kernel we huge.

Adding some printk's confirms this.  Broken kernel:

	vfs_caches_init() mempages: 4026972
	vfs_caches_init() reserve: 4021629
	vfs_caches_init() mempages (after reserve minus): 5343
	files_init() n: 2137
	files_init() files_stat.max_files: 8192

Working kernel:

	vfs_caches_init() mempages: 4026972
	vfs_caches_init() reserve: 375
	vfs_caches_init() mempages2: 4026597
	files_init() n: 1610638
	files_init() files_stat.max_files: 1610638

Do we have an alternative to call instead of nr_free_pages() in
vfs_caches_init()?

I guess we could save off 'nr_initialized' in memmap_init_zone() and
then use "nr_initialized - nr_free_pages()", but that seems a bit hackish.
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