Messages in this thread | | | Date | Wed, 18 Dec 2013 20:50:19 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH -mm 4/7] mm: thp: turn put_compound_page() into __put_page_tail() |
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On 12/18, Peter Zijlstra wrote: > > On Wed, Dec 18, 2013 at 08:19:58PM +0100, Oleg Nesterov wrote: > > @@ -247,7 +242,7 @@ bool __get_page_tail(struct page *page) > > bool got; > > struct page *page_head = compound_trans_head(page); > > > > - /* Ref to put_compound_page() comment. */ > > + /* Ref to __put_page_tail() comment. */ > > if (!__compound_tail_refcounted(page_head)) { > > smp_rmb(); > > if (likely(PageTail(page))) { > > What code is this against, my local tree doesn't have that smp_rmb().
This is against -mm code.
> This suggests its a recent patch; which is good since then we can still > drop it and wait for people to send one with a proper comment in.
put_compound_page() explains this barrier, this is what "Ref" above means, I guess.
To remind, I think we can do more cleanups here.
Oleg.
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