Re: [PATCH] Fix panic in __d_lookup with high dentry hashtable counts

From: Al Viro
Date: Fri Jan 13 2012 - 11:22:48 EST


On Fri, Jan 13, 2012 at 09:52:37AM -0600, Dimitri Sivanich wrote:
> When the number of dentry cache hash table entries gets too high
> (2147483648 entries), use of a signed integer in the initialization
> loop prevents the dentry_hashtable from getting initialized, resulting
> in a panic in __d_lookup. Fixing this in dcache_init and a few other
> spots for consistency.

> static void __init dcache_init(void)
> {
> - int loop;
> + long loop;

You've got to be kidding. Note that D_HASHMASK is at most 32bit. Use
of long here is an overkill and so's 2^31 hash buckets (that's what,
16Gb in hash list heads alone? What kind of average chain length do
you expect, BTW?)

Can alloc_large_system_hash() produce the horrors that large, anyway?
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