On Sun, Jul 28, 2019 at 10:43:35PM -0700, Song Liu wrote: > 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 khugepaged_add_pte_mapped_thp(). > > Signed-off-by: Song Liu <songliubrav...@fb.com> > --- > kernel/events/uprobes.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c > index 58ab7fc7272a..cc53789fefc6 100644 > --- a/kernel/events/uprobes.c > +++ b/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> > > @@ -470,6 +471,7 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, > struct mm_struct *mm, > 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); > @@ -525,6 +527,9 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, > struct mm_struct *mm, > > /* dec_mm_counter for old_page */ > dec_mm_counter(mm, MM_ANONPAGES); > + > + if (PageCompound(orig_page)) > + orig_page_huge = true; > } > put_page(orig_page); > } > @@ -543,6 +548,10 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, > struct mm_struct *mm, > if (ret && is_register && ref_ctr_updated) > update_ref_ctr(uprobe, mm, -1); > > + /* try collapse pmd for compound page */ > + if (!ret && orig_page_huge) > + khugepaged_add_pte_mapped_thp(mm, vaddr & HPAGE_PMD_MASK); > +
IIUC, here you have all locks taken, so you should be able to call collapse_pte_mapped_thp() directly, shouldn't you? -- Kirill A. Shutemov
