From: Michel Lespinasse <walken@xxxxxxxxxx>
Introduce a single location where filemap_fault() locks the desired page.
There used to be two such places, depending if the initial find_get_page()
was successful or not.
Signed-off-by: Michel Lespinasse <walken@xxxxxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>
Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>
Reviewed-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Cc: Ying Han <yinghan@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: <linux-arch@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/filemap.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
diff -puN mm/filemap.c~mm-filemap_fault-unique-path-for-locking-page mm/filemap.c
--- a/mm/filemap.c~mm-filemap_fault-unique-path-for-locking-page
+++ a/mm/filemap.c
@@ -1539,25 +1539,27 @@ int filemap_fault(struct vm_area_struct
* waiting for the lock.
*/
do_async_mmap_readahead(vma, ra, file, page, offset);
- lock_page(page);
-
- /* Did it get truncated? */
- if (unlikely(page->mapping != mapping)) {
- unlock_page(page);
- put_page(page);
- goto no_cached_page;
- }
} else {
/* No page in the page cache at all */
do_sync_mmap_readahead(vma, ra, file, offset);
count_vm_event(PGMAJFAULT);
ret = VM_FAULT_MAJOR;
retry_find:
- page = find_lock_page(mapping, offset);
+ page = find_get_page(mapping, offset);
if (!page)
goto no_cached_page;
}
+ lock_page(page);
+
+ /* Did it get truncated? */
+ if (unlikely(page->mapping != mapping)) {
+ unlock_page(page);
+ put_page(page);
+ goto retry_find;
+ }
+ VM_BUG_ON(page->index != offset);
+
/*
* We have a locked page in the page cache, now we need to check
* that it's up-to-date. If not, it is going to be due to an error.
_
--
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