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docs: pagemap: fix flags location, member name and sample code

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The userland visible page flags (KPF_*) were initially moved to
include/linux/kernel-page-flags.h in commit 1a9b5b7fe0 ("mm: export
stable page flags"), and later moved to
include/uapi/linux/kernel-page-flags.h in commit 607ca46e97 ("UAPI:
(Scripted) Disintegrate include/linux").  Update the doc to reflect the
current location of these flags.

The member @walk_end of struct pm_scan_arg {} was wrongly written as
"end_walk".

The first sample code of the PAGEMAP_SCAN ioctl wrongly used the
PM_SCAN_CHECK_WPASYNC flag twice, instead of the PM_SCAN_WP_MATCHING flag.
The second one included the wrong category in the required mask -
PAGE_IS_FILE should be used instead of PAGE_IS_SWAPPED as per the
intention.

Fix them all together.

Signed-off-by: Zenghui Yu <zenghui.yu@linux.dev>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Reviewed-by: SeongJae Park <sj@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <20260626162710.25844-1-zenghui.yu@linux.dev>
This commit is contained in:
Zenghui Yu 2026-06-27 00:27:10 +08:00 committed by Jonathan Corbet
parent d1bb650229
commit 711719631f
1 changed files with 4 additions and 4 deletions
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8
Documentation/admin-guide/mm/pagemap.rst
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@ -67,7 +67,7 @@ number of times a page is mapped.
* ``/proc/kpageflags``. This file contains a 64-bit set of flags for each
page, indexed by PFN.
The flags are (from ``fs/proc/page.c``, above kpageflags_read):
The flags are (from ``include/uapi/linux/kernel-page-flags.h``):
0. LOCKED
1. ERROR
@ -264,7 +264,7 @@ The ``struct pm_scan_arg`` is used as the argument of the IOCTL.
provided or not.
3. The range is specified through ``start`` and ``end``.
4. The walk can abort before visiting the complete range such as the user buffer
can get full etc. The walk ending address is specified in``end_walk``.
can get full etc. The walk ending address is specified in ``walk_end``.
5. The output buffer of ``struct page_region`` array and size is specified in
``vec`` and ``vec_len``.
6. The optional maximum requested pages are specified in the ``max_pages``.
@ -275,7 +275,7 @@ Find pages which have been written and WP them as well::
struct pm_scan_arg arg = {
.size = sizeof(arg),
.flags = PM_SCAN_CHECK_WPASYNC | PM_SCAN_CHECK_WPASYNC,
.flags = PM_SCAN_WP_MATCHING | PM_SCAN_CHECK_WPASYNC,
..
.category_mask = PAGE_IS_WRITTEN,
.return_mask = PAGE_IS_WRITTEN,
@ -288,7 +288,7 @@ present or huge::
.size = sizeof(arg),
.flags = 0,
..
.category_mask = PAGE_IS_WRITTEN | PAGE_IS_SWAPPED,
.category_mask = PAGE_IS_WRITTEN | PAGE_IS_FILE,
.category_inverted = PAGE_IS_SWAPPED,
.category_anyof_mask = PAGE_IS_PRESENT | PAGE_IS_HUGE,
.return_mask = PAGE_IS_WRITTEN | PAGE_IS_SWAPPED |