mm: zswap: fix potential memory corruption on duplicate store

While stress-testing zswap a memory corruption was happening when writing
back pages.  __frontswap_store used to check for duplicate entries before
attempting to store a page in zswap, this was because if the store fails
the old entry isn't removed from the tree.  This change removes duplicate
entries in zswap_store before the actual attempt.

[[email protected]: add a warning and a comment, per Johannes]
  Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 42c06a0e8ebe ("mm: kill frontswap")
Signed-off-by: Domenico Cerasuolo <[email protected]>
Acked-by: Johannes Weiner <[email protected]>
Acked-by: Nhat Pham <[email protected]>
Cc: Dan Streetman <[email protected]>
Cc: Domenico Cerasuolo <[email protected]>
Cc: Seth Jennings <[email protected]>
Cc: Vitaly Wool <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions