From: Song Liu <songliubraving@xxxxxx> Subject: uprobe: collapse THP pmd after removing all uprobes After all uprobes are removed from the huge page (with PTE pgtable), it is possible to collapse the pmd and benefit from THP again. This patch does the collapse by calling collapse_pte_mapped_thp(). Link: http://lkml.kernel.org/r/20190815164525.1848545-7-songliubraving@xxxxxx Signed-off-by: Song Liu <songliubraving@xxxxxx> Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Reported-by: kbuild test robot <lkp@xxxxxxxxx> Reviewed-by: Oleg Nesterov <oleg@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/events/uprobes.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/kernel/events/uprobes.c~uprobe-collapse-thp-pmd-after-removing-all-uprobes +++ a/kernel/events/uprobes.c @@ -26,6 +26,7 @@ #include <linux/percpu-rwsem.h> #include <linux/task_work.h> #include <linux/shmem_fs.h> +#include <linux/khugepaged.h> #include <linux/uprobes.h> @@ -472,6 +473,7 @@ int uprobe_write_opcode(struct arch_upro struct page *old_page, *new_page; struct vm_area_struct *vma; int ret, is_register, ref_ctr_updated = 0; + bool orig_page_huge = false; is_register = is_swbp_insn(&opcode); uprobe = container_of(auprobe, struct uprobe, arch); @@ -529,6 +531,9 @@ retry: /* let go new_page */ put_page(new_page); new_page = NULL; + + if (PageCompound(orig_page)) + orig_page_huge = true; } put_page(orig_page); } @@ -547,6 +552,10 @@ put_old: if (ret && is_register && ref_ctr_updated) update_ref_ctr(uprobe, mm, -1); + /* try collapse pmd for compound page */ + if (!ret && orig_page_huge) + collapse_pte_mapped_thp(mm, vaddr); + return ret; } _
