Messages in this thread | | | Date | Sun, 8 Sep 2013 20:32:03 -0700 | Subject | Re: [PATCH v7 1/4] spinlock: A new lockref structure for lockless update of refcount | From | Linus Torvalds <> |
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On Sun, Sep 8, 2013 at 5:03 PM, Al Viro <viro@zeniv.linux.org.uk> wrote: > > There's one exception - basically, we decide to put duplicates of > reference(s) we hold into (a bunch of) structures being created. If > we decide that we'd failed and need to roll back, the structures > need to be taken out of whatever lists, etc. they'd been already > put on and references held in them - dropped. That removal gets done > under a spinlock. Sure, we can string those structures on some kind > of temp list, drop the spinlock and do dput() on everything in there, > but it's much more convenient to just free them as we are evicting > them, doing dput() as we go. Which is safe, since we are still have > the references used to create these buggers pinned down.
Hmm. Which codepath does this? Because I got curious and added back the __might_sleep() unconditionally to dput() just to see (now that I think that the dput() bugs are gone), and at least under normal load it doesn't trigger. I even wrote a thing that just constantly creates and renames the target file concurrently with looking it up, so that I've stress-tested the RCU sequence number failure path (and verified with a profile that yes, it does trigger the "oops, need to retry" case). I didn't test anything odd at all (just my dentry stress tests and a regular graphical desktop), though.
And I have too much memory to sanely stress any out-of-memory situations.
#firstworldkerneldeveloperproblems
Linus
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