From: Song Liu <songliubraving@xxxxxx> Subject: uprobe: use FOLL_SPLIT_PMD instead of FOLL_SPLIT Use the newly added FOLL_SPLIT_PMD in uprobe. This preserves the huge page when the uprobe is enabled. When the uprobe is disabled, newer instances of the same application could still benefit from huge page. For the next step, we will enable khugepaged to regroup the pmd, so that existing instances of the application could also benefit from huge page after the uprobe is disabled. Link: http://lkml.kernel.org/r/20190815164525.1848545-5-songliubraving@xxxxxx Signed-off-by: Song Liu <songliubraving@xxxxxx> Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Reviewed-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx> Reviewed-by: Oleg Nesterov <oleg@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/events/uprobes.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) --- a/kernel/events/uprobes.c~uprobe-use-foll_split_pmd-instead-of-foll_split +++ a/kernel/events/uprobes.c @@ -155,7 +155,7 @@ static int __replace_page(struct vm_area { struct mm_struct *mm = vma->vm_mm; struct page_vma_mapped_walk pvmw = { - .page = old_page, + .page = compound_head(old_page), .vma = vma, .address = addr, }; @@ -166,8 +166,6 @@ static int __replace_page(struct vm_area mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm, addr, addr + PAGE_SIZE); - VM_BUG_ON_PAGE(PageTransHuge(old_page), old_page); - if (new_page) { err = mem_cgroup_try_charge(new_page, vma->vm_mm, GFP_KERNEL, &memcg, false); @@ -481,7 +479,7 @@ int uprobe_write_opcode(struct arch_upro retry: /* Read the page with vaddr into memory */ ret = get_user_pages_remote(NULL, mm, vaddr, 1, - FOLL_FORCE | FOLL_SPLIT, &old_page, &vma, NULL); + FOLL_FORCE | FOLL_SPLIT_PMD, &old_page, &vma, NULL); if (ret <= 0) return ret; _
