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From: Yu Zhao <yuzhao@google.com>
To: Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@suse.com>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: "Peter Zijlstra" <peterz@infradead.org>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Arnaldo Carvalho de Melo" <acme@kernel.org>,
	"Alexander Shishkin" <alexander.shishkin@linux.intel.com>,
	"Jiri Olsa" <jolsa@redhat.com>,
	"Namhyung Kim" <namhyung@kernel.org>,
	"Vlastimil Babka" <vbabka@suse.cz>,
	"Hugh Dickins" <hughd@google.com>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Andrea Arcangeli" <aarcange@redhat.com>,
	"Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
	"David Rientjes" <rientjes@google.com>,
	"Matthew Wilcox" <willy@infradead.org>,
	"Lance Roy" <ldr709@gmail.com>,
	"Ralph Campbell" <rcampbell@nvidia.com>,
	"Jason Gunthorpe" <jgg@ziepe.ca>,
	"Dave Airlie" <airlied@redhat.com>,
	"Thomas Hellstrom" <thellstrom@vmware.com>,
	"Souptick Joarder" <jrdr.linux@gmail.com>,
	"Mel Gorman" <mgorman@suse.de>, "Jan Kara" <jack@suse.cz>,
	"Mike Kravetz" <mike.kravetz@oracle.com>,
	"Huang Ying" <ying.huang@intel.com>,
	"Aaron Lu" <ziqian.lzq@antfin.com>,
	"Omar Sandoval" <osandov@fb.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Vineeth Remanan Pillai" <vpillai@digitalocean.com>,
	"Daniel Jordan" <daniel.m.jordan@oracle.com>,
	"Mike Rapoport" <rppt@linux.ibm.com>,
	"Joel Fernandes" <joel@joelfernandes.org>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"Alexander Duyck" <alexander.h.duyck@linux.intel.com>,
	"Pavel Tatashin" <pavel.tatashin@microsoft.com>,
	"David Hildenbrand" <david@redhat.com>,
	"Juergen Gross" <jgross@suse.com>,
	"Anthony Yznaga" <anthony.yznaga@oracle.com>,
	"Johannes Weiner" <hannes@cmpxchg.org>,
	"Darrick J . Wong" <darrick.wong@oracle.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	"Yu Zhao" <yuzhao@google.com>
Subject: [PATCH v3 1/4] mm: remove unnecessary smp_wmb() in collapse_huge_page()
Date: Tue, 24 Sep 2019 17:24:56 -0600	[thread overview]
Message-ID: <20190924232459.214097-1-yuzhao@google.com> (raw)
In-Reply-To: <20190914070518.112954-1-yuzhao@google.com>

__SetPageUptodate() always has a built-in smp_wmb() to make sure
user data copied to a new page appears before set_pmd_at().

Signed-off-by: Yu Zhao <yuzhao@google.com>
---
 mm/khugepaged.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index ccede2425c3f..70ff98e1414d 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1067,13 +1067,6 @@ static void collapse_huge_page(struct mm_struct *mm,
 	_pmd = mk_huge_pmd(new_page, vma->vm_page_prot);
 	_pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
 
-	/*
-	 * spin_lock() below is not the equivalent of smp_wmb(), so
-	 * this is needed to avoid the copy_huge_page writes to become
-	 * visible after the set_pmd_at() write.
-	 */
-	smp_wmb();
-
 	spin_lock(pmd_ptl);
 	BUG_ON(!pmd_none(*pmd));
 	page_add_new_anon_rmap(new_page, vma, address, true);
-- 
2.23.0.351.gc4317032e6-goog


  parent reply	other threads:[~2019-09-24 23:25 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-08 22:56 [PATCH] mm: don't expose page to fast gup before it's ready Yu Zhao
2018-01-09  8:46 ` Michal Hocko
2018-01-09 10:10   ` Yu Zhao
2018-01-31 23:07     ` Andrew Morton
2019-05-14 21:25     ` Andrew Morton
2019-05-14 23:07       ` Yu Zhao
2019-09-14  7:05         ` [PATCH v2] mm: don't expose page to fast gup prematurely Yu Zhao
2019-09-24 11:23           ` Kirill A. Shutemov
2019-09-24 22:05             ` Yu Zhao
2019-09-25 12:17               ` Kirill A. Shutemov
2019-09-26  3:58                 ` Yu Zhao
2019-09-24 23:24           ` Yu Zhao [this message]
2019-09-24 23:24             ` [PATCH v3 2/4] mm: don't expose hugetlb " Yu Zhao
2019-09-24 23:24             ` [PATCH v3 3/4] mm: don't expose non-hugetlb " Yu Zhao
2019-09-25  8:25               ` Peter Zijlstra
2019-09-25 22:26                 ` Yu Zhao
2019-09-26 10:20                   ` Kirill A. Shutemov
2019-09-27  3:26                     ` John Hubbard
2019-09-27 12:33                       ` Michal Hocko
     [not found]                       ` <20190927050648.GA92494@google.com>
     [not found]                         ` <712513fe-f064-c965-d165-80d43cfc606f@nvidia.com>
2019-10-02  0:00                           ` Yu Zhao
2019-09-24 23:24             ` [PATCH v3 4/4] mm: remove unnecessary smp_wmb() in __SetPageUptodate() Yu Zhao
2019-09-24 23:50               ` Matthew Wilcox
2019-09-25 22:03                 ` Yu Zhao

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