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commit 541e06b772c1aaffb3b6a245ccface36d7107af2 upstream. Preallocations are common in the VMA code to avoid allocating under certain locking conditions. The preallocations must also cover the worst-case scenario. Removing the GFP_ZERO flag from the kmem_cache_alloc() (and bulk variant) calls will reduce the amount of time spent zeroing memory that may not be used. Only zero out the necessary area to keep track of the allocations in the maple state. Zero the entire node prior to using it in the tree. This required internal changes to node counting on allocation, so the test code is also updated. This restores some micro-benchmark performance: up to +9% in mmtests mmap1 by my testing +10% to +20% in mmap, mmapaddr, mmapmany tests reported by Red Hat Link: https://bugzilla.redhat.com/show_bug.cgi?id=2149636 Link: https://lkml.kernel.org/r/20230105160427.2988454-1-Liam.Howlett@oracle.com Cc: stable@vger.kernel.org Fixes: 54a611b60590 ("Maple Tree: add new data structure") Signed-off-by: Liam Howlett <Liam.Howlett@oracle.com> Reported-by: Jirka Hladky <jhladky@redhat.com> Suggested-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>