linux-kernel - [PATCH] docs: update THP admin guide about non-tmpfs filesystem support

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Message-ID: <20250403103805.173761-1-kernel@pankajraghav.com>
Date: Thu,  3 Apr 2025 12:38:05 +0200
From: "Pankaj Raghav (Samsung)" <kernel@...kajraghav.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
	Jonathan Corbet <corbet@....net>
Cc: linux-kernel@...r.kernel.org,
	willy@...radead.org,
	linux-mm@...ck.org,
	David Hildenbrand <david@...hat.com>,
	da.gomez@...nel.org,
	mcgrof@...nel.org,
	gost.dev@...sung.com,
	linux-doc@...r.kernel.org,
	kernel@...kajraghav.com,
	Pankaj Raghav <p.raghav@...sung.com>
Subject: [PATCH] docs: update THP admin guide about non-tmpfs filesystem support

From: Pankaj Raghav <p.raghav@...sung.com>

THP support for non-tmpfs filesystem has been around for some time now.
Update the admin guide to reflect it.

Signed-off-by: Pankaj Raghav <p.raghav@...sung.com>
---
 Documentation/admin-guide/mm/transhuge.rst | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
index dff8d5985f0f..01b7ce90d693 100644
--- a/Documentation/admin-guide/mm/transhuge.rst
+++ b/Documentation/admin-guide/mm/transhuge.rst
@@ -12,8 +12,8 @@ using huge pages for the backing of virtual memory with huge pages
 that supports the automatic promotion and demotion of page sizes and
 without the shortcomings of hugetlbfs.
 
-Currently THP only works for anonymous memory mappings and tmpfs/shmem.
-But in the future it can expand to other filesystems.
+Currently, THP only works for anonymous memory mappings, tmpfs/shmem and
+filesystems that support large folios.
 
 .. note::
    in the examples below we presume that the basic page size is 4K and
@@ -463,6 +463,10 @@ fields for each mapping. (Note that AnonHugePages only applies to traditional
 PMD-sized THP for historical reasons and should have been called
 AnonHugePmdMapped).
 
+The number of PMD-sized transparent huge pages currently used by
+filesystem data (page cache) is available by reading the FileHugePages field
+in ``/proc/meminfo``.
+
 The number of file transparent huge pages mapped to userspace is available
 by reading ShmemPmdMapped and ShmemHugePages fields in ``/proc/meminfo``.
 To identify what applications are mapping file transparent huge pages, it

base-commit: f0a16f5363325cc8d9382471cdc7b654c53254c9
-- 
2.44.1