Commit c1cb20d4 authored Nov 30, 2018 by Yu Zhao Committed by Linus Torvalds Nov 30, 2018

mm: use swp_offset as key in shmem_replace_page()

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: f6ab1f7f ("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>

parent 6ff38bd4

mm/shmem.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -1509,11 +1509,13 @@ 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);

		/*
		@@ -1532,7 +1534,7 @@ 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);

		/*

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