From 20ca87f22b82d5fbf1938e1668ac4f55d749fb8f Mon Sep 17 00:00:00 2001 From: Li Xinhai Date: Wed, 1 Apr 2020 21:10:52 -0700 Subject: mm/mempolicy: check hugepage migration is supported by arch in vma_migratable() vma_migratable() is called to check if pages in vma can be migrated before go ahead to further actions. Currently it is used in below code path: - task_numa_work - mbind - move_pages For hugetlb mapping, whether vma is migratable or not is determined by: - CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION - arch_hugetlb_migration_supported Issue: current code only checks for CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION alone, and no code should use it directly. (note that current code in vma_migratable don't cause failure or bug because unmap_and_move_huge_page() will catch unsupported hugepage and handle it properly) This patch checks the two factors by hugepage_migration_supported for impoving code logic and robustness. It will enable early bail out of hugepage migration procedure, but because currently all architecture supporting hugepage migration is able to support all page size, we would not see performance gain with this patch applied. vma_migratable() is moved to mm/mempolicy.c, because of the circular reference of mempolicy.h and hugetlb.h cause defining it as inline not feasible. Signed-off-by: Li Xinhai Signed-off-by: Andrew Morton Reviewed-by: Mike Kravetz Acked-by: Michal Hocko Cc: Anshuman Khandual Cc: Naoya Horiguchi Link: http://lkml.kernel.org/r/1579786179-30633-1-git-send-email-lixinhai.lxh@gmail.com Signed-off-by: Linus Torvalds --- mm/mempolicy.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) (limited to 'mm') diff --git a/mm/mempolicy.c b/mm/mempolicy.c index b190cd456ace..58e3dfa2f83a 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1743,6 +1743,34 @@ COMPAT_SYSCALL_DEFINE4(migrate_pages, compat_pid_t, pid, #endif /* CONFIG_COMPAT */ +bool vma_migratable(struct vm_area_struct *vma) +{ + if (vma->vm_flags & (VM_IO | VM_PFNMAP)) + return false; + + /* + * DAX device mappings require predictable access latency, so avoid + * incurring periodic faults. + */ + if (vma_is_dax(vma)) + return false; + + if (is_vm_hugetlb_page(vma) && + !hugepage_migration_supported(hstate_vma(vma))) + return false; + + /* + * Migration allocates pages in the highest zone. If we cannot + * do so then migration (at least from node to node) is not + * possible. + */ + if (vma->vm_file && + gfp_zone(mapping_gfp_mask(vma->vm_file->f_mapping)) + < policy_zone) + return false; + return true; +} + struct mempolicy *__get_vma_policy(struct vm_area_struct *vma, unsigned long addr) { -- cgit v1.2.3