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mm: invalidation check mapping before folio_contains 

Enabling tmpfs "direct IO" exposes it to invalidate_inode_pages2_range(),
which when swapping can hit the VM_BUG_ON_FOLIO(!folio_contains()): the
folio has been moved from page cache to swap cache (with folio->mapping
reset to NULL), but the folio_index() embedded in folio_contains() sees
swapcache, and so returns the swapcache_index() - whereas folio->index
would be the right one to check against the index from mapping's xarray.

There are different ways to fix this, but my preference is just to order
the checks in invalidate_inode_pages2_range() the same way that they are
in __filemap_get_folio() and find_lock_entries() and filemap_fault():
check folio->mapping before folio_contains().

Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Message-Id: <f0b31772-78d7-f198-6482-9f25aab8c13f@google.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Hugh Dickins 2023-08-08 21:36:12 -07:00 committed by Christian Brauner
parent e88e0d366f
commit aa5b9178c0
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1 changed files with 2 additions and 2 deletions
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4
mm/truncate.c
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@ -657,11 +657,11 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
}
folio_lock(folio);
VM_BUG_ON_FOLIO(!folio_contains(folio, indices[i]), folio);
if (folio->mapping != mapping) {
if (unlikely(folio->mapping != mapping)) {
folio_unlock(folio);
continue;
}
VM_BUG_ON_FOLIO(!folio_contains(folio, indices[i]), folio);
folio_wait_writeback(folio);
if (folio_mapped(folio))