From: Peter Zijlstra <peterz@infradead.org>
To: "Liang, Kan" <kan.liang@linux.intel.com>
Cc: Will Deacon <will@kernel.org>,
Michael Ellerman <mpe@ellerman.id.au>,
mingo@redhat.com, acme@kernel.org, linux-kernel@vger.kernel.org,
mark.rutland@arm.com, alexander.shishkin@linux.intel.com,
jolsa@redhat.com, eranian@google.com, ak@linux.intel.com,
dave.hansen@intel.com, kirill.shutemov@linux.intel.com,
benh@kernel.crashing.org, paulus@samba.org,
David Miller <davem@davemloft.net>
Subject: Re: [PATCH V9 1/4] perf/core: Add PERF_SAMPLE_DATA_PAGE_SIZE
Date: Wed, 11 Nov 2020 10:57:50 +0100 [thread overview]
Message-ID: <20201111095750.GS2594@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <8e88ba79-7c40-ea32-a7ed-bdc4fc04b2af@linux.intel.com>
On Wed, Nov 04, 2020 at 12:11:16PM -0500, Liang, Kan wrote:
> On 10/13/2020 12:34 PM, Peter Zijlstra wrote:
> > @@ -7037,13 +7057,20 @@ static u64 __perf_get_page_size(struct m
> > return 0;
> > }
> > + page = pte_page(*pte);
> > + if (PageHuge(page)) {
> > + u64 size = page_size(compound_head(page));
> > + pte_unmap(pte);
> > + return size;
> > + }
> > +
>
> The PageHuge() check for PTE crashes my machine when I did page size test.
> (Sorry, I didn't find the issue earlier. I just found some time to re-run
> the page size test.)
>
> It seems we don't need the check for PTE here. The size should be always
> PAGE_SIZE, no? After I remove the check, everything looks good.
That's the thing, an architecture could have non-page-table aligned
huge-pages. For example using 4 consecutive 4k pages to create 16k
pages. In that case the above code would trigger and find a 16k compound
page with HUGETLB_PAGE_DTOR (assuming it was created through hugetlbfs).
What is this page size test; I'd like to reproduce.
next prev parent reply other threads:[~2020-11-11 9:58 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-01 13:57 [PATCH V9 0/4] Add the page size in the perf record (kernel) kan.liang
2020-10-01 13:57 ` [PATCH V9 1/4] perf/core: Add PERF_SAMPLE_DATA_PAGE_SIZE kan.liang
2020-10-09 9:09 ` Peter Zijlstra
2020-10-09 9:16 ` Peter Zijlstra
2020-10-09 9:37 ` Will Deacon
2020-10-09 9:53 ` Peter Zijlstra
2020-10-20 2:49 ` Leo Yan
2020-10-20 7:19 ` Peter Zijlstra
2020-10-20 8:16 ` Leo Yan
2020-10-09 12:29 ` Liang, Kan
2020-10-09 12:57 ` Peter Zijlstra
2020-10-09 13:28 ` Michael Ellerman
2020-10-12 8:48 ` Will Deacon
2020-10-13 14:57 ` Liang, Kan
2020-10-13 15:46 ` Peter Zijlstra
2020-10-13 16:34 ` Peter Zijlstra
2020-11-04 17:11 ` Liang, Kan
2020-11-10 15:20 ` Liang, Kan
2020-11-11 9:57 ` Peter Zijlstra [this message]
2020-11-11 11:22 ` Peter Zijlstra
2020-11-11 12:43 ` Peter Zijlstra
2020-11-11 15:30 ` Matthew Wilcox
2020-11-11 15:52 ` Peter Zijlstra
2020-11-11 15:57 ` Peter Zijlstra
2020-11-11 16:38 ` Matthew Wilcox
2020-11-11 17:22 ` Peter Zijlstra
2020-11-11 18:26 ` Matthew Wilcox
2020-11-11 20:00 ` Peter Zijlstra
2020-11-11 22:33 ` Matthew Wilcox
2020-11-12 9:53 ` Peter Zijlstra
2020-11-12 11:36 ` Peter Zijlstra
2020-11-12 14:01 ` Matthew Wilcox
2020-10-29 10:51 ` [tip: perf/core] " tip-bot2 for Kan Liang
2020-10-01 13:57 ` [PATCH V9 2/4] perf/x86/intel: Support PERF_SAMPLE_DATA_PAGE_SIZE kan.liang
2020-10-29 10:51 ` [tip: perf/core] " tip-bot2 for Kan Liang
2020-10-01 13:57 ` [PATCH V9 3/4] powerpc/perf: " kan.liang
2020-10-29 10:51 ` [tip: perf/core] " tip-bot2 for Kan Liang
2020-10-01 13:57 ` [PATCH V9 4/4] perf/core: Add support for PERF_SAMPLE_CODE_PAGE_SIZE kan.liang
2020-10-29 10:51 ` [tip: perf/core] " tip-bot2 for Stephane Eranian
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