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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@fb.com
Signed-off-by: Song Liu <songliubraving@fb.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Song Liu 2019-09-23 15:38:27 -07:00 committed by Linus Torvalds
parent bfe7b00de6
commit 5a52c9df62
1 changed files with 2 additions and 4 deletions
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6
kernel/events/uprobes.c
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@ -155,7 +155,7 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
{
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_struct *vma, unsigned long addr,
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_uprobe *auprobe, struct mm_struct *mm,
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;