From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Michal Hocko <mhocko@suse.com>, Hugh Dickins <hughd@google.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Ben Hutchings <ben@decadent.org.uk>
Subject: [PATCH 3.18 03/12] mm, thp: Do not make page table dirty unconditionally in touch_p[mu]d()
Date: Mon, 4 Dec 2017 16:59:17 +0100 [thread overview]
Message-ID: <20171204155916.616760251@linuxfoundation.org> (raw)
In-Reply-To: <20171204155916.489136969@linuxfoundation.org>
3.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
commit a8f97366452ed491d13cf1e44241bc0b5740b1f0 upstream.
Currently, we unconditionally make page table dirty in touch_pmd().
It may result in false-positive can_follow_write_pmd().
We may avoid the situation, if we would only make the page table entry
dirty if caller asks for write access -- FOLL_WRITE.
The patch also changes touch_pud() in the same way.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[Salvatore Bonaccorso: backport for 3.16:
- Adjust context
- Drop specific part for PUD-sized transparent hugepages. Support
for PUD-sized transparent hugepages was added in v4.11-rc1
]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
mm/huge_memory.c | 14 ++++----------
1 file changed, 4 insertions(+), 10 deletions(-)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1240,17 +1240,11 @@ struct page *follow_trans_huge_pmd(struc
VM_BUG_ON_PAGE(!PageHead(page), page);
if (flags & FOLL_TOUCH) {
pmd_t _pmd;
- /*
- * We should set the dirty bit only for FOLL_WRITE but
- * for now the dirty bit in the pmd is meaningless.
- * And if the dirty bit will become meaningful and
- * we'll only set it with FOLL_WRITE, an atomic
- * set_bit will be required on the pmd to set the
- * young bit, instead of the current set_pmd_at.
- */
- _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
+ _pmd = pmd_mkyoung(*pmd);
+ if (flags & FOLL_WRITE)
+ _pmd = pmd_mkdirty(_pmd);
if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
- pmd, _pmd, 1))
+ pmd, _pmd, flags & FOLL_WRITE))
update_mmu_cache_pmd(vma, addr, pmd);
}
if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
next prev parent reply other threads:[~2017-12-04 16:44 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-04 15:59 [PATCH 3.18 00/12] 3.18.86-stable review Greg Kroah-Hartman
2017-12-04 15:59 ` [PATCH 3.18 01/12] netlink: add a start callback for starting a netlink dump Greg Kroah-Hartman
2017-12-04 15:59 ` [PATCH 3.18 02/12] ipsec: Fix aborted xfrm policy dump crash Greg Kroah-Hartman
2017-12-04 15:59 ` Greg Kroah-Hartman [this message]
2017-12-04 15:59 ` [PATCH 3.18 04/12] mm/madvise.c: fix madvise() infinite loop under special circumstances Greg Kroah-Hartman
2017-12-04 15:59 ` [PATCH 3.18 05/12] btrfs: clear space cache inode generation always Greg Kroah-Hartman
2017-12-04 15:59 ` [PATCH 3.18 08/12] eeprom: at24: check at24_read/write arguments Greg Kroah-Hartman
2017-12-04 15:59 ` [PATCH 3.18 09/12] drm/panel: simple: Add missing panel_simple_unprepare() calls Greg Kroah-Hartman
2017-12-04 15:59 ` [PATCH 3.18 10/12] NFS: revalidate "." etc correctly on "open" Greg Kroah-Hartman
2017-12-04 20:14 ` [PATCH 3.18 00/12] 3.18.86-stable review Shuah Khan
2017-12-04 23:45 ` Guenter Roeck
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