Messages in this thread | | | Date | Mon, 15 Feb 2010 11:24:53 -0500 | From | Christoph Hellwig <> | Subject | Re: [PATCH 2/3] mm: Implement writeback livelock avoidance using page tagging |
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On Tue, Feb 16, 2010 at 03:21:27AM +1100, Nick Piggin wrote: > Also, I wonder what you think about leaving the tags dangling when > the loop bails out early? I have a *slight* concern about this > because previously we never have a tag set when radix_tree_delete > is called. I actually had a bug in that code in earlier versions > of rcu radix tree that only got found by the user test harness. > And another slight concern that it is just a bit ugly to leave the > tag. But I can accept that lower CPU overhead trumps ugliness :)
The XFS inode cache calls radix_tree_delete with a tag set, and interestingly enough we're trying to catch a very weird bug in that area currently, which seems more or less directly related to the use of tags. But we also had a real locking bug related to tags, so I'm not yet sure what the issue is back until I hear back from the bug reported and reproducer.
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