Re: [PATCHv4 18/24] thp, mm: split_huge_page(): caller need to lock page
On Mon, Mar 30, 2015 at 07:40:29PM +0530, Aneesh Kumar K.V wrote: > "Kirill A. Shutemov" writes: > > > We're going to use migration entries instead of compound_lock() to > > stabilize page refcounts. Setup and remove migration entries require > > page to be locked. > > > > Some of split_huge_page() callers already have the page locked. Let's > > require everybody to lock the page before calling split_huge_page(). > > > > Signed-off-by: Kirill A. Shutemov > > Why not have split_huge_page_locked/unlocked, and call the one which > takes lock internally every where ? We could do that, but it's not obvoius for me what is benefit. Couple of lines on caller side? -- Kirill A. Shutemov -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCHv4 18/24] thp, mm: split_huge_page(): caller need to lock page
"Kirill A. Shutemov" writes: > We're going to use migration entries instead of compound_lock() to > stabilize page refcounts. Setup and remove migration entries require > page to be locked. > > Some of split_huge_page() callers already have the page locked. Let's > require everybody to lock the page before calling split_huge_page(). > > Signed-off-by: Kirill A. Shutemov Why not have split_huge_page_locked/unlocked, and call the one which takes lock internally every where ? -aneesh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCHv4 18/24] thp, mm: split_huge_page(): caller need to lock page
Kirill A. Shutemov kirill.shute...@linux.intel.com writes: We're going to use migration entries instead of compound_lock() to stabilize page refcounts. Setup and remove migration entries require page to be locked. Some of split_huge_page() callers already have the page locked. Let's require everybody to lock the page before calling split_huge_page(). Signed-off-by: Kirill A. Shutemov kirill.shute...@linux.intel.com Why not have split_huge_page_locked/unlocked, and call the one which takes lock internally every where ? -aneesh -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCHv4 18/24] thp, mm: split_huge_page(): caller need to lock page
On Mon, Mar 30, 2015 at 07:40:29PM +0530, Aneesh Kumar K.V wrote: Kirill A. Shutemov kirill.shute...@linux.intel.com writes: We're going to use migration entries instead of compound_lock() to stabilize page refcounts. Setup and remove migration entries require page to be locked. Some of split_huge_page() callers already have the page locked. Let's require everybody to lock the page before calling split_huge_page(). Signed-off-by: Kirill A. Shutemov kirill.shute...@linux.intel.com Why not have split_huge_page_locked/unlocked, and call the one which takes lock internally every where ? We could do that, but it's not obvoius for me what is benefit. Couple of lines on caller side? -- Kirill A. Shutemov -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCHv4 18/24] thp, mm: split_huge_page(): caller need to lock page
We're going to use migration entries instead of compound_lock() to
stabilize page refcounts. Setup and remove migration entries require
page to be locked.
Some of split_huge_page() callers already have the page locked. Let's
require everybody to lock the page before calling split_huge_page().
Signed-off-by: Kirill A. Shutemov
---
mm/huge_memory.c| 1 +
mm/ksm.c| 6 --
mm/memory-failure.c | 12 +---
mm/migrate.c| 8 ++--
4 files changed, 20 insertions(+), 7 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 3741f81e423e..f1d88b9059e2 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1846,6 +1846,7 @@ int split_huge_page_to_list(struct page *page, struct
list_head *list)
BUG_ON(is_huge_zero_page(page));
BUG_ON(!PageAnon(page));
+ BUG_ON(!PageLocked(page));
/*
* The caller does not necessarily hold an mmap_sem that would prevent
diff --git a/mm/ksm.c b/mm/ksm.c
index 92182eeba87d..a8a88b0f6f62 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -987,9 +987,11 @@ static int page_trans_compound_anon_split(struct page
*page)
* Recheck we got the reference while the head
* was still anonymous.
*/
- if (PageAnon(transhuge_head))
+ if (PageAnon(transhuge_head)) {
+ lock_page(transhuge_head);
ret = split_huge_page(transhuge_head);
- else
+ unlock_page(transhuge_head);
+ } else
/*
* Retry later if split_huge_page run
* from under us.
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index d487f8dc6d39..74c5aaddae85 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -950,7 +950,10 @@ static int hwpoison_user_mappings(struct page *p, unsigned
long pfn,
* enough * to be safe.
*/
if (!PageHuge(hpage) && PageAnon(hpage)) {
- if (unlikely(split_huge_page(hpage))) {
+ lock_page(hpage);
+ ret = split_huge_page(hpage);
+ unlock_page(hpage);
+ if (unlikely(ret)) {
/*
* FIXME: if splitting THP is failed, it is
* better to stop the following operation rather
@@ -1694,10 +1697,13 @@ int soft_offline_page(struct page *page, int flags)
return -EBUSY;
}
if (!PageHuge(page) && PageTransHuge(hpage)) {
- if (PageAnon(hpage) && unlikely(split_huge_page(hpage))) {
+ lock_page(page);
+ ret = split_huge_page(hpage);
+ unlock_page(page);
+ if (unlikely(ret)) {
pr_info("soft offline: %#lx: failed to split THP\n",
pfn);
- return -EBUSY;
+ return ret;
}
}
diff --git a/mm/migrate.c b/mm/migrate.c
index 01449826b914..91a67029bb18 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -920,9 +920,13 @@ static int unmap_and_move(new_page_t get_new_page,
free_page_t put_new_page,
goto out;
}
- if (unlikely(PageTransHuge(page)))
- if (unlikely(split_huge_page(page)))
+ if (unlikely(PageTransHuge(page))) {
+ lock_page(page);
+ rc = split_huge_page(page);
+ unlock_page(page);
+ if (rc)
goto out;
+ }
rc = __unmap_and_move(page, newpage, force, mode);
--
2.1.4
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[PATCHv4 18/24] thp, mm: split_huge_page(): caller need to lock page
We're going to use migration entries instead of compound_lock() to
stabilize page refcounts. Setup and remove migration entries require
page to be locked.
Some of split_huge_page() callers already have the page locked. Let's
require everybody to lock the page before calling split_huge_page().
Signed-off-by: Kirill A. Shutemov kirill.shute...@linux.intel.com
---
mm/huge_memory.c| 1 +
mm/ksm.c| 6 --
mm/memory-failure.c | 12 +---
mm/migrate.c| 8 ++--
4 files changed, 20 insertions(+), 7 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 3741f81e423e..f1d88b9059e2 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1846,6 +1846,7 @@ int split_huge_page_to_list(struct page *page, struct
list_head *list)
BUG_ON(is_huge_zero_page(page));
BUG_ON(!PageAnon(page));
+ BUG_ON(!PageLocked(page));
/*
* The caller does not necessarily hold an mmap_sem that would prevent
diff --git a/mm/ksm.c b/mm/ksm.c
index 92182eeba87d..a8a88b0f6f62 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -987,9 +987,11 @@ static int page_trans_compound_anon_split(struct page
*page)
* Recheck we got the reference while the head
* was still anonymous.
*/
- if (PageAnon(transhuge_head))
+ if (PageAnon(transhuge_head)) {
+ lock_page(transhuge_head);
ret = split_huge_page(transhuge_head);
- else
+ unlock_page(transhuge_head);
+ } else
/*
* Retry later if split_huge_page run
* from under us.
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index d487f8dc6d39..74c5aaddae85 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -950,7 +950,10 @@ static int hwpoison_user_mappings(struct page *p, unsigned
long pfn,
* enough * to be safe.
*/
if (!PageHuge(hpage) PageAnon(hpage)) {
- if (unlikely(split_huge_page(hpage))) {
+ lock_page(hpage);
+ ret = split_huge_page(hpage);
+ unlock_page(hpage);
+ if (unlikely(ret)) {
/*
* FIXME: if splitting THP is failed, it is
* better to stop the following operation rather
@@ -1694,10 +1697,13 @@ int soft_offline_page(struct page *page, int flags)
return -EBUSY;
}
if (!PageHuge(page) PageTransHuge(hpage)) {
- if (PageAnon(hpage) unlikely(split_huge_page(hpage))) {
+ lock_page(page);
+ ret = split_huge_page(hpage);
+ unlock_page(page);
+ if (unlikely(ret)) {
pr_info(soft offline: %#lx: failed to split THP\n,
pfn);
- return -EBUSY;
+ return ret;
}
}
diff --git a/mm/migrate.c b/mm/migrate.c
index 01449826b914..91a67029bb18 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -920,9 +920,13 @@ static int unmap_and_move(new_page_t get_new_page,
free_page_t put_new_page,
goto out;
}
- if (unlikely(PageTransHuge(page)))
- if (unlikely(split_huge_page(page)))
+ if (unlikely(PageTransHuge(page))) {
+ lock_page(page);
+ rc = split_huge_page(page);
+ unlock_page(page);
+ if (rc)
goto out;
+ }
rc = __unmap_and_move(page, newpage, force, mode);
--
2.1.4
--
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
