Messages in this thread | | | Date | Tue, 10 Dec 2019 16:29:39 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 1/2] perf/x86/intel/bts: Remove a silly warning |
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On Thu, Dec 05, 2019 at 05:28:52PM +0300, Alexander Shishkin wrote: > There is no comment or record anywhere that would explain the train of > thought that went into this warning, it probably tried to make sure that > the high order allocations indeed happened in the ring buffer code. >
> --- a/arch/x86/events/intel/bts.c > +++ b/arch/x86/events/intel/bts.c > @@ -83,8 +83,6 @@ bts_buffer_setup_aux(struct perf_event *event, void **pages, > /* count all the high order buffers */ > for (pg = 0, nbuf = 0; pg < nr_pages;) { > page = virt_to_page(pages[pg]); > - if (WARN_ON_ONCE(!PagePrivate(page) && nr_pages > 1)) > - return NULL; > pg += 1 << page_private(page);
I'm thinking that because ^^^^ uses page_private(), it wants to make sure PagePrivate().
I haven't checked the current rules, but using page_private() without PagePrivate() seems dodgy.
Also consider:
+ __nr_pages = PagePrivate(page) ? 1 << page_private(page) : 1;
> nbuf++; > } > -- > 2.24.0 >
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