When allocating large anonymous folios, we want to maximize our chances of being able to use the highest order we support. Since one of the constraints is that a folio has to be mapped naturally aligned, let's have mmap default to that alignment when user space does not provide a hint. With this in place, an extra 2% of all allocated anonymous memory belongs to a folio of the highest order, when compiling the kernel. Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx> --- mm/mmap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index ff68a67a2a7c..e7652001a32e 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1627,7 +1627,7 @@ generic_get_unmapped_area(struct file *filp, unsigned long addr, info.length = len; info.low_limit = mm->mmap_base; info.high_limit = mmap_end; - info.align_mask = 0; + info.align_mask = BIT(PAGE_SHIFT + ANON_FOLIO_ORDER_MAX) - 1; info.align_offset = 0; return vm_unmapped_area(&info); } @@ -1677,7 +1677,7 @@ generic_get_unmapped_area_topdown(struct file *filp, unsigned long addr, info.length = len; info.low_limit = max(PAGE_SIZE, mmap_min_addr); info.high_limit = arch_get_mmap_base(addr, mm->mmap_base); - info.align_mask = 0; + info.align_mask = BIT(PAGE_SHIFT + ANON_FOLIO_ORDER_MAX) - 1; info.align_offset = 0; addr = vm_unmapped_area(&info); -- 2.25.1
