mm: swapoff: shmem_find_swap_entries() filter out other types

Swapfile "type" was passed all the way down to shmem_unuse_inode(), but
then forgotten from shmem_find_swap_entries(): with the result that
removing one swapfile would try to free up all the swap from shmem - no
problem when only one swapfile anyway, but counter-productive when more,
causing swapoff to be unnecessarily OOM-killed when it should succeed.

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1904081254470.1523@eggly.anvils
Fixes: b56a2d8af914 ("mm: rid swapoff of quadratic complexity")
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca>
Cc: Vineeth Pillai <vpillai@digitalocean.com>
Cc: Kelley Nielsen <kelleynnn@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Huang Ying <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 9 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index b3db3779a30a..859e8628071f 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1099,10 +1099,11 @@ extern struct swap_info_struct *swap_info[];
 static int shmem_find_swap_entries(struct address_space *mapping,
                                    pgoff_t start, unsigned int nr_entries,
                                    struct page **entries, pgoff_t *indices,
-                                   bool frontswap)
+                                   unsigned int type, bool frontswap)
 {
         XA_STATE(xas, &mapping->i_pages, start);
         struct page *page;
+        swp_entry_t entry;
         unsigned int ret = 0;
 
         if (!nr_entries)
@@ -1116,13 +1117,12 @@ static int shmem_find_swap_entries(struct address_space *mapping,
                 if (!xa_is_value(page))
                         continue;
 
-                if (frontswap) {
-                        swp_entry_t entry = radix_to_swp_entry(page);
-
-                        if (!frontswap_test(swap_info[swp_type(entry)],
-                                            swp_offset(entry)))
-                                continue;
-                }
+                entry = radix_to_swp_entry(page);
+                if (swp_type(entry) != type)
+                        continue;
+                if (frontswap &&
+                    !frontswap_test(swap_info[type], swp_offset(entry)))
+                        continue;
 
                 indices[ret] = xas.xa_index;
                 entries[ret] = page;
@@ -1194,7 +1194,7 @@ static int shmem_unuse_inode(struct inode *inode, unsigned int type,
 
                 pvec.nr = shmem_find_swap_entries(mapping, start, nr_entries,
                                                   pvec.pages, indices,
-                                                  frontswap);
+                                                  type, frontswap);
                 if (pvec.nr == 0) {
                         ret = 0;
                         break;