lkml.org 
[lkml]   [2019]   [Jul]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/2] uprobe: collapse THP pmd after removing all uprobes
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 <songliubraving@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

\
 
 \ /
  Last update: 2019-07-30 17:02    [W:0.219 / U:0.012 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site