The patch titled
Subject: mm: shmem: control THP support through the kernel command line
has been added to the -mm mm-unstable branch. Its filename is
mm-shmem-control-thp-support-through-the-kernel-command-line.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-shmem-control-thp-support-through-the-kernel-command-line.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: MaÃra Canal <mcanal@xxxxxxxxxx>
Subject: mm: shmem: control THP support through the kernel command line
Date: Fri, 1 Nov 2024 13:54:06 -0300
Patch series "mm: add more kernel parameters to control mTHP", v5.
This series introduces four patches related to the kernel parameters
controlling mTHP and a fifth patch replacing `strcpy()` for `strscpy()` in
the file `mm/huge_memory.c`.
The first patch is a straightforward documentation update, correcting the
format of the kernel parameter ``thp_anon=``.
The second, third, and fourth patches focus on controlling THP support for
shmem via the kernel command line. The second patch introduces a
parameter to control the global default huge page allocation policy for
the internal shmem mount. The third patch moves a piece of code to a
shared header to ease the implementation of the fourth patch. Finally,
the fourth patch implements a parameter similar to ``thp_anon=``, but for
shmem.
The goal of these changes is to simplify the configuration of systems that
rely on mTHP support for shmem. For instance, a platform with a GPU that
benefits from huge pages may want to enable huge pages for shmem. Having
these kernel parameters streamlines the configuration process and ensures
consistency across setups.
This patch (of 4):
Add a new kernel command line to control the hugepage allocation policy
for the internal shmem mount, ``transparent_hugepage_shmem``. The
parameter is similar to ``transparent_hugepage`` and has the following
format:
transparent_hugepage_shmem=<policy>
where ``<policy>`` is one of the seven valid policies available for
shmem.
Configuring the default huge page allocation policy for the internal
shmem mount can be beneficial for DRM GPU drivers. Just as CPU
architectures, GPUs can also take advantage of huge pages, but this is
possible only if DRM GEM objects are backed by huge pages.
Since GEM uses shmem to allocate anonymous pageable memory, having control
over the default huge page allocation policy allows for the exploration of
huge pages use on GPUs that rely on GEM objects backed by shmem.
Link: https://lkml.kernel.org/r/20241101165719.1074234-2-mcanal@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20241101165719.1074234-4-mcanal@xxxxxxxxxx
Signed-off-by: MaÃra Canal <mcanal@xxxxxxxxxx>
Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Barry Song <baohua@xxxxxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: kernel-dev@xxxxxxxxxx
Cc: Lance Yang <ioworker0@xxxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/admin-guide/kernel-parameters.txt | 7 +
Documentation/admin-guide/mm/transhuge.rst | 6 +
mm/shmem.c | 72 +++++++++-----
3 files changed, 62 insertions(+), 23 deletions(-)
--- a/Documentation/admin-guide/kernel-parameters.txt~mm-shmem-control-thp-support-through-the-kernel-command-line
+++ a/Documentation/admin-guide/kernel-parameters.txt
@@ -6926,6 +6926,13 @@
See Documentation/admin-guide/mm/transhuge.rst
for more details.
+ transparent_hugepage_shmem= [KNL]
+ Format: [always|within_size|advise|never|deny|force]
+ Can be used to control the hugepage allocation policy for
+ the internal shmem mount.
+ See Documentation/admin-guide/mm/transhuge.rst
+ for more details.
+
trusted.source= [KEYS]
Format: <string>
This parameter identifies the trust source as a backend
--- a/Documentation/admin-guide/mm/transhuge.rst~mm-shmem-control-thp-support-through-the-kernel-command-line
+++ a/Documentation/admin-guide/mm/transhuge.rst
@@ -326,6 +326,12 @@ PMD_ORDER THP policy will be overridden.
is not defined within a valid ``thp_anon``, its policy will default to
``never``.
+Similarly to ``transparent_hugepage``, you can control the hugepage
+allocation policy for the internal shmem mount by using the kernel parameter
+``transparent_hugepage_shmem=<policy>``, where ``<policy>`` is one of the
+seven valid policies for shmem (``always``, ``within_size``, ``advise``,
+``never``, ``deny``, and ``force``).
+
Hugepages in tmpfs/shmem
========================
--- a/mm/shmem.c~mm-shmem-control-thp-support-through-the-kernel-command-line
+++ a/mm/shmem.c
@@ -582,24 +582,39 @@ static bool shmem_huge_global_enabled(st
}
}
-#if defined(CONFIG_SYSFS)
static int shmem_parse_huge(const char *str)
{
+ int huge;
+
+ if (!str)
+ return -EINVAL;
+
if (!strcmp(str, "never"))
- return SHMEM_HUGE_NEVER;
- if (!strcmp(str, "always"))
- return SHMEM_HUGE_ALWAYS;
- if (!strcmp(str, "within_size"))
- return SHMEM_HUGE_WITHIN_SIZE;
- if (!strcmp(str, "advise"))
- return SHMEM_HUGE_ADVISE;
- if (!strcmp(str, "deny"))
- return SHMEM_HUGE_DENY;
- if (!strcmp(str, "force"))
- return SHMEM_HUGE_FORCE;
- return -EINVAL;
+ huge = SHMEM_HUGE_NEVER;
+ else if (!strcmp(str, "always"))
+ huge = SHMEM_HUGE_ALWAYS;
+ else if (!strcmp(str, "within_size"))
+ huge = SHMEM_HUGE_WITHIN_SIZE;
+ else if (!strcmp(str, "advise"))
+ huge = SHMEM_HUGE_ADVISE;
+ else if (!strcmp(str, "deny"))
+ huge = SHMEM_HUGE_DENY;
+ else if (!strcmp(str, "force"))
+ huge = SHMEM_HUGE_FORCE;
+ else
+ return -EINVAL;
+
+ if (!has_transparent_hugepage() &&
+ huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
+ return -EINVAL;
+
+ /* Do not override huge allocation policy with non-PMD sized mTHP */
+ if (huge == SHMEM_HUGE_FORCE &&
+ huge_shmem_orders_inherit != BIT(HPAGE_PMD_ORDER))
+ return -EINVAL;
+
+ return huge;
}
-#endif
#if defined(CONFIG_SYSFS) || defined(CONFIG_TMPFS)
static const char *shmem_format_huge(int huge)
@@ -5065,15 +5080,7 @@ static ssize_t shmem_enabled_store(struc
huge = shmem_parse_huge(tmp);
if (huge == -EINVAL)
- return -EINVAL;
- if (!has_transparent_hugepage() &&
- huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
- return -EINVAL;
-
- /* Do not override huge allocation policy with non-PMD sized mTHP */
- if (huge == SHMEM_HUGE_FORCE &&
- huge_shmem_orders_inherit != BIT(HPAGE_PMD_ORDER))
- return -EINVAL;
+ return huge;
shmem_huge = huge;
if (shmem_huge > SHMEM_HUGE_DENY)
@@ -5170,6 +5177,25 @@ struct kobj_attribute thpsize_shmem_enab
__ATTR(shmem_enabled, 0644, thpsize_shmem_enabled_show, thpsize_shmem_enabled_store);
#endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_SYSFS */
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE)
+
+static int __init setup_transparent_hugepage_shmem(char *str)
+{
+ int huge;
+
+ huge = shmem_parse_huge(str);
+ if (huge == -EINVAL) {
+ pr_warn("transparent_hugepage_shmem= cannot parse, ignored\n");
+ return huge;
+ }
+
+ shmem_huge = huge;
+ return 1;
+}
+__setup("transparent_hugepage_shmem=", setup_transparent_hugepage_shmem);
+
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
#else /* !CONFIG_SHMEM */
/*
_
Patches currently in -mm which might be from mcanal@xxxxxxxxxx are
mm-fix-docs-for-the-kernel-parameter-thp_anon=.patch
mm-shmem-control-thp-support-through-the-kernel-command-line.patch
mm-move-get_order_from_str-to-internalh.patch
mm-shmem-override-mthp-shmem-default-with-a-kernel-parameter.patch
mm-huge_memory-use-strscpy-instead-of-strcpy.patch
