From: Peter Xu <peterx@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: peterx@redhat.com, "Andrea Arcangeli" <aarcange@redhat.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
"Michal Hocko" <mhocko@suse.com>,
"Zi Yan" <zi.yan@cs.rutgers.edu>,
"Huang Ying" <ying.huang@intel.com>,
"Dan Williams" <dan.j.williams@intel.com>,
"Naoya Horiguchi" <n-horiguchi@ah.jp.nec.com>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
"Konstantin Khlebnikov" <khlebnikov@yandex-team.ru>,
"Souptick Joarder" <jrdr.linux@gmail.com>,
linux-mm@kvack.org
Subject: [PATCH] mm: hugepage: mark splitted page dirty when needed
Date: Tue, 4 Sep 2018 15:55:10 +0800 [thread overview]
Message-ID: <20180904075510.22338-1-peterx@redhat.com> (raw)
When splitting a huge page, we should set all small pages as dirty if
the original huge page has the dirty bit set before. Otherwise we'll
lose the original dirty bit.
CC: Andrea Arcangeli <aarcange@redhat.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
CC: Michal Hocko <mhocko@suse.com>
CC: Zi Yan <zi.yan@cs.rutgers.edu>
CC: Huang Ying <ying.huang@intel.com>
CC: Dan Williams <dan.j.williams@intel.com>
CC: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
CC: "Jérôme Glisse" <jglisse@redhat.com>
CC: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
CC: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
CC: Souptick Joarder <jrdr.linux@gmail.com>
CC: linux-mm@kvack.org
CC: linux-kernel@vger.kernel.org
Signed-off-by: Peter Xu <peterx@redhat.com>
---
To the reviewers: I'm new to the mm world so sorry if this patch is
making silly mistakes, however it did solve a problem for me when
testing with a customized Linux tree mostly based on Andrea's userfault
write-protect work. Without the change, my customized QEMU/tcg tree
will not be able to do correct UFFDIO_WRITEPROTECT and then QEMU will
get a SIGBUS when faulting multiple times. With the change (or of
course disabling THP) then UFFDIO_WRITEPROTECT will be able to correctly
resolve the write protections then it runs well. Any comment would be
welcomed. TIA.
---
mm/huge_memory.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index c3bc7e9c9a2a..0754a16923d5 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2176,6 +2176,8 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
entry = pte_mkold(entry);
if (soft_dirty)
entry = pte_mksoft_dirty(entry);
+ if (dirty)
+ entry = pte_mkdirty(entry);
}
pte = pte_offset_map(&_pmd, addr);
BUG_ON(!pte_none(*pte));
--
2.17.1
next reply other threads:[~2018-09-04 7:55 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-04 7:55 Peter Xu [this message]
2018-09-04 8:01 ` [PATCH] mm: hugepage: mark splitted page dirty when needed Kirill A. Shutemov
2018-09-04 14:00 ` Zi Yan
2018-09-05 7:30 ` Peter Xu
2018-09-05 12:49 ` Zi Yan
2018-09-06 11:43 ` Peter Xu
2018-09-05 12:55 ` Kirill A. Shutemov
2018-09-06 11:39 ` Peter Xu
2018-09-06 14:08 ` Kirill A. Shutemov
2018-09-07 4:35 ` Peter Xu
2018-09-07 17:54 ` Jerome Glisse
2018-09-10 4:07 ` Peter Xu
2018-09-06 14:17 ` Jerome Glisse
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