mm/shmem: fix infinite loop when swap in shmem error at swapoff time

When swap in shmem error at swapoff time, there would be a infinite loop
in the while loop in shmem_unuse_inode().  It's because swapin error is
deliberately ignored now and thus info->swapped will never reach 0.  So we
can't escape the loop in shmem_unuse().

In order to fix the issue, swapin_error entry is stored in the mapping
when swapin error occurs.  So the swapcache page can be freed and the user
won't end up with a permanently mounted swap because a sector is bad.  If
the page is accessed later, the user process will be killed so that
corrupted data is never consumed.  On the other hand, if the page is never
accessed, the user won't even notice it.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Miaohe Lin <[email protected]>
Reported-by: Naoya Horiguchi <[email protected]>
Reviewed-by: Naoya Horiguchi <[email protected]>
Cc: Alistair Popple <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Howells <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: NeilBrown <[email protected]>
Cc: Peter Xu <[email protected]>
Cc: Ralph Campbell <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions