On 2024/10/28 01:36, Maíra Canal wrote:
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. By configuring the default hugepage allocation policy for the internal shmem mount, applications that use shmem, such as the DRM GEM objects, can take advantage of mTHP before it's been configured through sysfs. Signed-off-by: Maíra Canal <mcanal@xxxxxxxxxx> --- .../admin-guide/kernel-parameters.txt | 7 ++++ Documentation/admin-guide/mm/transhuge.rst | 6 +++ mm/shmem.c | 38 ++++++++++++++++++- 3 files changed, 49 insertions(+), 2 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 745055c3dc09..9b5b02c4d1ab 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.cindex 44282a296c33..24cdeafd8260 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -582,7 +582,6 @@ static bool shmem_huge_global_enabled(struct inode *inode, pgoff_t index, } }-#if defined(CONFIG_SYSFS)static int shmem_parse_huge(const char *str) { if (!strcmp(str, "never")) @@ -599,7 +598,6 @@ static int shmem_parse_huge(const char *str) return SHMEM_HUGE_FORCE; return -EINVAL; } -#endif#if defined(CONFIG_SYSFS) || defined(CONFIG_TMPFS)static const char *shmem_format_huge(int huge) @@ -5174,6 +5172,42 @@ 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, ret = 0; + + if (!str) + goto out; + + huge = shmem_parse_huge(str); + if (huge == -EINVAL) + goto out; + + if (!has_transparent_hugepage() && + huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY) { + ret = -EINVAL; + goto out; + } + + /* Do not override huge allocation policy with non-PMD sized mTHP */ + if (huge == SHMEM_HUGE_FORCE && + huge_shmem_orders_inherit != BIT(HPAGE_PMD_ORDER)) { + ret = -EINVAL; + goto out; + } + + shmem_huge = huge;
The code is similar to shmem_enabled_store(). Could you factor out the common parts into a helper function and reuse them?
+ return 1;
+out:
+ pr_warn("transparent_hugepage_shmem= cannot parse, ignored\n");
+ return ret;
+}
+__setup("transparent_hugepage_shmem=", setup_transparent_hugepage_shmem);
+
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
#else /* !CONFIG_SHMEM */
/*
