On Fri, Jul 17, 2015 at 01:22:02PM +0100, Mel Gorman wrote:
> From: Nicolai Stange <nicstange@xxxxxxxxx>
>
> Commit 0e1cc95b4cc7 ("mm: meminit: finish initialisation of struct pages
> before basic setup") introduced a rwsem to signal completion of the
> initialization workers.
>
> Lockdep complains about possible recursive locking:
> =============================================
> [ INFO: possible recursive locking detected ]
> 4.1.0-12802-g1dc51b8 #3 Not tainted
> ---------------------------------------------
> swapper/0/1 is trying to acquire lock:
> (pgdat_init_rwsem){++++.+},
> at: [<ffffffff8424c7fb>] page_alloc_init_late+0xc7/0xe6
>
> but task is already holding lock:
> (pgdat_init_rwsem){++++.+},
> at: [<ffffffff8424c772>] page_alloc_init_late+0x3e/0xe6
>
> Replace the rwsem by a completion together with an atomic
> "outstanding work counter".
>
> [peterz@xxxxxxxxxxxxx: Barrier removal on the grounds of being pointless]
> [mgorman@xxxxxxx: Applied review feedback]
> Signed-off-by: Nicolai Stange <nicstange@xxxxxxxxx>
> Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Thanks!
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