Re: [PATCH v7] mm: Add PM_THP_MAPPED to /proc/pid/pagemap
From: Matthew Wilcox <willy@infradead.org>
Date: 2021-11-28 04:21:13
Also in:
linux-fsdevel, linux-mm, lkml
On Mon, Nov 22, 2021 at 04:01:02PM -0800, Mina Almasry wrote:
Add PM_THP_MAPPED MAPPING to allow userspace to detect whether a given virt address is currently mapped by a transparent huge page or not. Example use case is a process requesting THPs from the kernel (via a huge tmpfs mount for example), for a performance critical region of memory. The userspace may want to query whether the kernel is actually backing this memory by hugepages or not.
But what is userspace going to _do_ differently if the kernel hasn't backed the memory with huge pages?