[RFC v2 06/10] mm: Add a range lock parameter to lock_page_or_retry()

Laurent Dufour
2017-05-24T11:20:47Z

As lock_page_or_retry() may release the mmap_sem, it has to know about
the range applying to the lock when using range locks.

This patch adds a new range parameter to __lock_page_or_retry() and
deals with the callers.

Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
---
include/linux/pagemap.h | 17 +++++++++++++++++
mm/filemap.c | 9 +++++++--
mm/memory.c | 3 ++-
3 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 316a19f6b635..efc62200d527 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -433,8 +433,13 @@ static inline pgoff_t linear_page_index(struct vm_area_struct *vma,

extern void __lock_page(struct page *page);
extern int __lock_page_killable(struct page *page);
+#ifdef CONFIG_MEM_RANGE_LOCK
+extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
+ unsigned int flags, struct range_lock *range);
+#else
extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
unsigned int flags);
+#endif
extern void unlock_page(struct page *page);

static inline int trylock_page(struct page *page)
@@ -473,12 +478,24 @@ static inline int lock_page_killable(struct page *page)
* Return value and mmap_sem implications depend on flags; see
* __lock_page_or_retry().
*/
+#ifdef CONFIG_MEM_RANGE_LOCK
static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm,
+ unsigned int flags,
+ struct range_lock *range)
+{
+ might_sleep();
+ return trylock_page(page) || __lock_page_or_retry(page, mm, flags,
+ range);
+}
+#else
+static inline int _lock_page_or_retry(struct page *page, struct mm_struct *mm,
unsigned int flags)
{
might_sleep();
return trylock_page(page) || __lock_page_or_retry(page, mm, flags);
}
+#define lock_page_or_retry(p, m, f, r) _lock_page_or_retry(p, m, f)
+#endif /* CONFIG_MEM_RANGE_LOCK */

/*
* This is exported only for wait_on_page_locked/wait_on_page_writeback, etc.,
diff --git a/mm/filemap.c b/mm/filemap.c
index 6f1be573a5e6..adb7c15b8aa4 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1053,7 +1053,11 @@ EXPORT_SYMBOL_GPL(__lock_page_killable);
* with the page locked and the mmap_sem unperturbed.
*/
int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
- unsigned int flags)
+ unsigned int flags
+#ifdef CONFIG_MEM_RANGE_LOCK
+ , struct range_lock *range
+#endif
+ )
{
if (flags & FAULT_FLAG_ALLOW_RETRY) {
/*
@@ -2234,7 +2238,8 @@ int filemap_fault(struct vm_fault *vmf)
goto no_cached_page;
}

- if (!lock_page_or_retry(page, vmf->vma->vm_mm, vmf->flags)) {
+ if (!lock_page_or_retry(page, vmf->vma->vm_mm, vmf->flags,
+ vmf->lockrange)) {
put_page(page);
return ret | VM_FAULT_RETRY;
}
diff --git a/mm/memory.c b/mm/memory.c
index aa080e9814d4..99f62156616e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2737,7 +2737,8 @@ int do_swap_page(struct vm_fault *vmf)
}

swapcache = page;
- locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
+ locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags,
+ vmf->lockrange);

delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
if (!locked) {
--
2.7.4