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>

diff --git a/mm/shmem.c b/mm/shmem.c
index b3db3779a30a1f1fbe2d5cda71ddc402601926ef..859e8628071f19c51a6eb65d2197809f43044ab1 100644 (file)
--- 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;