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authorMaíra Canal <mcanal@igalia.com>2024-11-01 13:54:06 -0300
committerAndrew Morton <akpm@linux-foundation.org>2024-11-11 13:09:43 -0800
commit949042811117d2f437ef6b529a69d45e2ee2d429 (patch)
tree83060176833f6e8639cd232ec09ac77588919fbd
parente3d37a6f62953962102607fe4491129271510990 (diff)
mm: shmem: control THP support through the kernel command line
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@igalia.com Link: https://lkml.kernel.org/r/20241101165719.1074234-4-mcanal@igalia.com Signed-off-by: Maíra Canal <mcanal@igalia.com> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Barry Song <baohua@kernel.org> Cc: dri-devel@lists.freedesktop.org Cc: Hugh Dickins <hughd@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: kernel-dev@igalia.com Cc: Lance Yang <ioworker0@gmail.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt7
-rw-r--r--Documentation/admin-guide/mm/transhuge.rst6
-rw-r--r--mm/shmem.c72
3 files changed, 62 insertions, 23 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 1666576acc0e..acabb04d0dd4 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/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
diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
index abdf10a1c7db..9c6f6da612c4 100644
--- a/Documentation/admin-guide/mm/transhuge.rst
+++ b/Documentation/admin-guide/mm/transhuge.rst
@@ -326,6 +326,12 @@ PMD_ORDER THP policy will be overridden. If the policy for PMD_ORDER
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
========================
diff --git a/mm/shmem.c b/mm/shmem.c
index 5afc5b1f7ae1..c83675c27190 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -582,24 +582,39 @@ static bool shmem_huge_global_enabled(struct inode *inode, pgoff_t index,
}
}
-#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(struct kobject *kobj,
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_enabled_attr =
__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 */
/*