On Mon, Jun 24, 2019 at 05:12:41PM -0700, Song Liu wrote: > Currently, filemap_fault() avoids trace condition with truncate by > checking page->mapping == mapping. This does not work for compound > pages. This patch let it check compound_head(page)->mapping instead. > > Acked-by: Rik van Riel <[email protected]> > Signed-off-by: Song Liu <[email protected]> > --- > mm/filemap.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/filemap.c b/mm/filemap.c > index df2006ba0cfa..f5b79a43946d 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -2517,7 +2517,7 @@ vm_fault_t filemap_fault(struct vm_fault *vmf) > goto out_retry; > > /* Did it get truncated? */ > - if (unlikely(page->mapping != mapping)) { > + if (unlikely(compound_head(page)->mapping != mapping)) {
There is another check like these in pagecache_get_page(), which is used by find_lock_page() and thus the truncate code (partial page truncate calls, but this could happen against read-only cache).
