Cc: Herbert Xu <herbert@...>, Rafael J. Wysocki <rjw@...>, LKML <linux-kernel@...>, Ingo Molnar <mingo@...>, Andrew Morton <akpm@...>, <linux-ext4@...>
No, not even then.
We *always* unhash the dentries before freeing them, but we very
consciously use "hlist_del_rcu()" on them, not "hlist_del_init()".
That, in turn, will mean that the "pprev" pointer will still be set, so
the "hlist_unhashed()" thing will *not* trigger.
IOW, when we do that direct-free with:
if (hlist_unhashed(&dentry->d_hash))
__d_free(dentry);
the "hlist_unhashed()" will literally guarantee that i has *never* been on
a hash-list at all!
(If you want to test whether it is currently unhashed or not, you actually
have to use "d_unhashed()" on the dentry under the dentry lock, which
tests the DCACHE_UNHASHED bit).
Of course, there could be some bug in there, but the thing is, none of
this has even changed in a long time, certainly not since 2.6.25. Which is
why I think the dcache code is all fine, and the bug comes from somewhere
else corrupting the data structures.
Linus
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