From d2d243df445a88c26e91eac02b041213c7a32e9e Mon Sep 17 00:00:00 2001 From: Baolin Wang Date: Sun, 22 Sep 2024 12:32:13 +0800 Subject: [PATCH] mm: shmem: fix khugepaged activation policy for shmem Shmem has a separate interface (different from anonymous pages) to control huge page allocation, that means shmem THP can be enabled while anonymous THP is disabled. However, in this case, khugepaged will not start to collapse shmem THP, which is unreasonable. To fix this issue, we should call start_stop_khugepaged() to activate or deactivate the khugepaged thread when setting shmem mTHP interfaces. Moreover, add a new helper shmem_hpage_pmd_enabled() to help to check whether shmem THP is enabled, which will determine if khugepaged should be activated. Link: https://lkml.kernel.org/r/9b9c6cbc4499bf44c6455367fd9e0f6036525680.1726978977.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang Reported-by: Ryan Roberts Reviewed-by: Ryan Roberts Cc: David Hildenbrand Cc: Hugh Dickins Cc: Matthew Wilcox Signed-off-by: Andrew Morton --- include/linux/shmem_fs.h | 6 ++++++ mm/khugepaged.c | 6 +++++- mm/shmem.c | 29 +++++++++++++++++++++++++++-- 3 files changed, 38 insertions(+), 3 deletions(-) diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h index 515a9a6a3c6f8..ee6635052383e 100644 --- a/include/linux/shmem_fs.h +++ b/include/linux/shmem_fs.h @@ -114,6 +114,7 @@ int shmem_unuse(unsigned int type); unsigned long shmem_allowable_huge_orders(struct inode *inode, struct vm_area_struct *vma, pgoff_t index, loff_t write_end, bool shmem_huge_force); +bool shmem_hpage_pmd_enabled(void); #else static inline unsigned long shmem_allowable_huge_orders(struct inode *inode, struct vm_area_struct *vma, pgoff_t index, @@ -121,6 +122,11 @@ static inline unsigned long shmem_allowable_huge_orders(struct inode *inode, { return 0; } + +static inline bool shmem_hpage_pmd_enabled(void) +{ + return false; +} #endif #ifdef CONFIG_SHMEM diff --git a/mm/khugepaged.c b/mm/khugepaged.c index b538c3d48386a..0bd80e134010f 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -416,9 +416,11 @@ static inline int hpage_collapse_test_exit_or_disable(struct mm_struct *mm) static bool hugepage_pmd_enabled(void) { /* - * We cover both the anon and the file-backed case here; file-backed + * We cover the anon, shmem and the file-backed case here; file-backed * hugepages, when configured in, are determined by the global control. * Anon pmd-sized hugepages are determined by the pmd-size control. + * Shmem pmd-sized hugepages are also determined by its pmd-size control, + * except when the global shmem_huge is set to SHMEM_HUGE_DENY. */ if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && hugepage_global_enabled()) @@ -430,6 +432,8 @@ static bool hugepage_pmd_enabled(void) if (test_bit(PMD_ORDER, &huge_anon_orders_inherit) && hugepage_global_enabled()) return true; + if (IS_ENABLED(CONFIG_SHMEM) && shmem_hpage_pmd_enabled()) + return true; return false; } diff --git a/mm/shmem.c b/mm/shmem.c index e87f5d6799a7b..6ad50ba60d8ef 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1655,6 +1655,23 @@ static gfp_t limit_gfp_mask(gfp_t huge_gfp, gfp_t limit_gfp) } #ifdef CONFIG_TRANSPARENT_HUGEPAGE +bool shmem_hpage_pmd_enabled(void) +{ + if (shmem_huge == SHMEM_HUGE_DENY) + return false; + if (test_bit(HPAGE_PMD_ORDER, &huge_shmem_orders_always)) + return true; + if (test_bit(HPAGE_PMD_ORDER, &huge_shmem_orders_madvise)) + return true; + if (test_bit(HPAGE_PMD_ORDER, &huge_shmem_orders_within_size)) + return true; + if (test_bit(HPAGE_PMD_ORDER, &huge_shmem_orders_inherit) && + shmem_huge != SHMEM_HUGE_NEVER) + return true; + + return false; +} + unsigned long shmem_allowable_huge_orders(struct inode *inode, struct vm_area_struct *vma, pgoff_t index, loff_t write_end, bool shmem_huge_force) @@ -5024,7 +5041,7 @@ static ssize_t shmem_enabled_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count) { char tmp[16]; - int huge; + int huge, err; if (count + 1 > sizeof(tmp)) return -EINVAL; @@ -5048,7 +5065,9 @@ static ssize_t shmem_enabled_store(struct kobject *kobj, shmem_huge = huge; if (shmem_huge > SHMEM_HUGE_DENY) SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge; - return count; + + err = start_stop_khugepaged(); + return err ? err : count; } struct kobj_attribute shmem_enabled_attr = __ATTR_RW(shmem_enabled); @@ -5125,6 +5144,12 @@ static ssize_t thpsize_shmem_enabled_store(struct kobject *kobj, ret = -EINVAL; } + if (ret > 0) { + int err = start_stop_khugepaged(); + + if (err) + ret = err; + } return ret; }