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mm: use swp_offset as key in shmem_replace_page()

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commit c1cb20d43728aa9b5393bd8d489bc85c142949b2 upstream.

We changed the key of swap cache tree from swp_entry_t.val to
swp_offset.  We need to do so in shmem_replace_page() as well.

Hugh said:
 "shmem_replace_page() has been wrong since the day I wrote it: good
  enough to work on swap "type" 0, which is all most people ever use
  (especially those few who need shmem_replace_page() at all), but
  broken once there are any non-0 swp_type bits set in the higher order
  bits"

Link: http://lkml.kernel.org/r/20181121215442.138545-1-yuzhao@google.com
Fixes: f6ab1f7f6b2d ("mm, swap: use offset of swap entry as key of swap cache")
Signed-off-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: Matthew Wilcox <willy@infradead.org>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org>	[4.9+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Yu Zhao 2018-11-30 14:09:03 -08:00 committed by Greg Kroah-Hartman
parent 397dbde614
commit 7c1ba1a1bb
1 changed files with 4 additions and 2 deletions
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6
mm/shmem.c
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@ -1532,11 +1532,13 @@ static int shmem_replace_page(struct page **pagep, gfp_t gfp,
{
struct page *oldpage, *newpage;
struct address_space *swap_mapping;
swp_entry_t entry;
pgoff_t swap_index;
int error;
oldpage = *pagep;
swap_index = page_private(oldpage);
entry.val = page_private(oldpage);
swap_index = swp_offset(entry);
swap_mapping = page_mapping(oldpage);
/*
@ -1555,7 +1557,7 @@ static int shmem_replace_page(struct page **pagep, gfp_t gfp,
__SetPageLocked(newpage);
__SetPageSwapBacked(newpage);
SetPageUptodate(newpage);
set_page_private(newpage, swap_index);
set_page_private(newpage, entry.val);
SetPageSwapCache(newpage);
/*