Re: [PATCH next 1/3] slub defrag: unpin writeback pages

[Pekka Enberg <penberg@cs.helsinki.fi>]

On Sun, 2008-10-05 at 03:25 +0100, Hugh Dickins wrote:
> A repetitive swapping load on powerpc G5 went progressively slower after
> nine hours: Inactive(file) was rising, as if inactive file pages pinned.
> Yes, slub defrag's kick_buffers() was forgetting to put_page() whenever
> it met a page already under writeback.
> 
> That PageWriteback test should be made while PageLocked in trigger_write(),
> just as it is in try_to_free_buffers() - if there are complex reasons why
> that's not actually necessary, I'd rather not have to think through them.
> A preliminary check before taking the lock?  No, it's not that important.
> 
> And trigger_write() must remember to unlock_page() in each of the cases
> where it doesn't reach the writepage().
> 
> Signed-off-by: Hugh Dickins <hugh@veritas.com>

Looks good to me. I've applied the patch now but would really like an
ACK from Christoph/Andrew as well. Thanks again, Hugh!

		Pekka

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