| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <1457737157-38573-17-git-send-email-kirill.shutemov@linux.intel.com>
Date: Sat, 12 Mar 2016 01:59:08 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Hugh Dickins <hughd@...gle.com>,
Andrea Arcangeli <aarcange@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: Dave Hansen <dave.hansen@...el.com>,
Vlastimil Babka <vbabka@...e.cz>,
Christoph Lameter <cl@...two.org>,
Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
Jerome Marchand <jmarchan@...hat.com>,
Yang Shi <yang.shi@...aro.org>,
Sasha Levin <sasha.levin@...cle.com>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
linux-fsdevel@...r.kernel.org,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCHv4 16/25] thp, mlock: do not mlock PTE-mapped file huge pages
As with anon THP, we only mlock file huge pages if we can prove that the
page is not mapped with PTE. This way we can avoid mlock leak into
non-mlocked vma on split.
We rely on PageDoubleMap() under lock_page() to check if the the page
may be PTE mapped. PG_double_map is set by page_add_file_rmap() when the
page mapped with PTEs.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
include/linux/page-flags.h | 13 ++++++++++++-
mm/huge_memory.c | 27 ++++++++++++++++++++-------
mm/mmap.c | 6 ++++++
mm/page_alloc.c | 2 ++
mm/rmap.c | 16 ++++++++++++++--
5 files changed, 54 insertions(+), 10 deletions(-)
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index f4ed4f1b0c77..517707ae8cd1 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -544,6 +544,17 @@ static inline int PageDoubleMap(struct page *page)
return PageHead(page) && test_bit(PG_double_map, &page[1].flags);
}
+static inline void SetPageDoubleMap(struct page *page)
+{
+ VM_BUG_ON_PAGE(!PageHead(page), page);
+ set_bit(PG_double_map, &page[1].flags);
+}
+
+static inline void ClearPageDoubleMap(struct page *page)
+{
+ VM_BUG_ON_PAGE(!PageHead(page), page);
+ clear_bit(PG_double_map, &page[1].flags);
+}
static inline int TestSetPageDoubleMap(struct page *page)
{
VM_BUG_ON_PAGE(!PageHead(page), page);
@@ -560,7 +571,7 @@ static inline int TestClearPageDoubleMap(struct page *page)
TESTPAGEFLAG_FALSE(TransHuge)
TESTPAGEFLAG_FALSE(TransCompound)
TESTPAGEFLAG_FALSE(TransTail)
-TESTPAGEFLAG_FALSE(DoubleMap)
+PAGEFLAG_FALSE(DoubleMap)
TESTSETFLAG_FALSE(DoubleMap)
TESTCLEARFLAG_FALSE(DoubleMap)
#endif
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index ba5fdf654f27..a2680b2112e4 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1427,6 +1427,8 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
* We don't mlock() pte-mapped THPs. This way we can avoid
* leaking mlocked pages into non-VM_LOCKED VMAs.
*
+ * For anon THP:
+ *
* In most cases the pmd is the only mapping of the page as we
* break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
* writable private mappings in populate_vma_page_range().
@@ -1434,15 +1436,26 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
* The only scenario when we have the page shared here is if we
* mlocking read-only mapping shared over fork(). We skip
* mlocking such pages.
+ *
+ * For file THP:
+ *
+ * We can expect PageDoubleMap() to be stable under page lock:
+ * for file pages we set it in page_add_file_rmap(), which
+ * requires page to be locked.
*/
- if (compound_mapcount(page) == 1 && !PageDoubleMap(page) &&
- page->mapping && trylock_page(page)) {
- lru_add_drain();
- if (page->mapping)
- mlock_vma_page(page);
- unlock_page(page);
- }
+
+ if (PageAnon(page) && compound_mapcount(page) != 1)
+ goto skip_mlock;
+ if (PageDoubleMap(page) || !page->mapping)
+ goto skip_mlock;
+ if (!trylock_page(page))
+ goto skip_mlock;
+ lru_add_drain();
+ if (page->mapping && !PageDoubleMap(page))
+ mlock_vma_page(page);
+ unlock_page(page);
}
+skip_mlock:
page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
VM_BUG_ON_PAGE(!PageCompound(page), page);
if (flags & FOLL_GET)
diff --git a/mm/mmap.c b/mm/mmap.c
index 94979671b42c..1786d0b0244f 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2576,6 +2576,12 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
/* drop PG_Mlocked flag for over-mapped range */
for (tmp = vma; tmp->vm_start >= start + size;
tmp = tmp->vm_next) {
+ /*
+ * Split pmd and munlock page on the border
+ * of the range.
+ */
+ vma_adjust_trans_huge(tmp, start, start + size, 0);
+
munlock_vma_pages_range(tmp,
max(tmp->vm_start, start),
min(tmp->vm_end, start + size));
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d6f042673e01..bce8b320fcce 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1009,6 +1009,8 @@ static bool free_pages_prepare(struct page *page, unsigned int order)
if (PageAnon(page))
page->mapping = NULL;
+ if (compound)
+ ClearPageDoubleMap(page);
bad += free_pages_check(page);
for (i = 1; i < (1 << order); i++) {
if (compound)
diff --git a/mm/rmap.c b/mm/rmap.c
index 359ec5cff9b0..f48258a78c8a 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1298,6 +1298,12 @@ void page_add_file_rmap(struct page *page, bool compound)
goto out;
__inc_zone_page_state(page, NR_FILE_THP_MAPPED);
} else {
+ if (PageTransCompound(page)) {
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
+ SetPageDoubleMap(compound_head(page));
+ if (PageMlocked(page))
+ clear_page_mlock(compound_head(page));
+ }
if (!atomic_inc_and_test(&page->_mapcount))
goto out;
}
@@ -1472,8 +1478,14 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
*/
if (!(flags & TTU_IGNORE_MLOCK)) {
if (vma->vm_flags & VM_LOCKED) {
- /* Holding pte lock, we do *not* need mmap_sem here */
- mlock_vma_page(page);
+ /* PTE-mapped THP are never mlocked */
+ if (!PageTransCompound(page)) {
+ /*
+ * Holding pte lock, we do *not* need
+ * mmap_sem here
+ */
+ mlock_vma_page(page);
+ }
ret = SWAP_MLOCK;
goto out_unmap;
}
--
2.7.0
Powered by blists - more mailing lists