mm: filemap: fix mapping->nrpages double accounting in fuse
Commit 22f2ac51 ("mm: workingset: fix crash in shadow node shrinker caused by replace_page_cache_page()") switched replace_page_cache() from raw radix tree operations to page_cache_tree_insert() but didn't take into account that the latter function, unlike the raw radix tree op, handles mapping->nrpages. As a result, that counter is bumped for each page replacement rather than balanced out even. The mapping->nrpages counter is used to skip needless radix tree walks when invalidating, truncating, syncing inodes without pages, as well as statistics for userspace. Since the error is positive, we'll do more page cache tree walks than necessary; we won't miss a necessary one. And we'll report more buffer pages to userspace than there are. The error is limited to fuse inodes. Fixes: 22f2ac51 ("mm: workingset: fix crash in shadow node shrinker caused by replace_page_cache_page()") Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: stable@vger.kernel.org Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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