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authorHugh Dickins <hughd@google.com>2014-03-20 21:52:17 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-03-20 22:09:09 -0700
commit7e09e738afd21ef99f047425fc0b0c9be8b03254 (patch)
tree423cb848a7d6875509b99720d4afcfa208bac078 /mm/rmap.c
parent3fb725c48b93c0a152174b6dbbc1029b5e734c7b (diff)
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mm: fix swapops.h:131 bug if remap_file_pages raced migration
Add remove_linear_migration_ptes_from_nonlinear(), to fix an interesting little include/linux/swapops.h:131 BUG_ON(!PageLocked) found by trinity: indicating that remove_migration_ptes() failed to find one of the migration entries that was temporarily inserted. The problem comes from remap_file_pages()'s switch from vma_interval_tree (good for inserting the migration entry) to i_mmap_nonlinear list (no good for locating it again); but can only be a problem if the remap_file_pages() range does not cover the whole of the vma (zap_pte() clears the range). remove_migration_ptes() needs a file_nonlinear method to go down the i_mmap_nonlinear list, applying linear location to look for migration entries in those vmas too, just in case there was this race. The file_nonlinear method does need rmap_walk_control.arg to do this; but it never needed vma passed in - vma comes from its own iteration. Reported-and-tested-by: Dave Jones <davej@redhat.com> Reported-and-tested-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/rmap.c')
-rw-r--r--mm/rmap.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index d9d42316a99a..8fc049f9a5a6 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1360,8 +1360,9 @@ static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount,
}
static int try_to_unmap_nonlinear(struct page *page,
- struct address_space *mapping, struct vm_area_struct *vma)
+ struct address_space *mapping, void *arg)
{
+ struct vm_area_struct *vma;
int ret = SWAP_AGAIN;
unsigned long cursor;
unsigned long max_nl_cursor = 0;
@@ -1663,7 +1664,7 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc)
if (list_empty(&mapping->i_mmap_nonlinear))
goto done;
- ret = rwc->file_nonlinear(page, mapping, vma);
+ ret = rwc->file_nonlinear(page, mapping, rwc->arg);
done:
mutex_unlock(&mapping->i_mmap_mutex);