diff mbox series

[v13,4/6] uprobe: use FOLL_SPLIT_PMD instead of FOLL_SPLIT

Message ID 20190815164525.1848545-5-songliubraving@fb.com (mailing list archive)
State New, archived
Headers show
Series THP aware uprobe | expand

Commit Message

Song Liu Aug. 15, 2019, 4:45 p.m. UTC 
This patch uses 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.

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: Song Liu <songliubraving@fb.com>
---
 kernel/events/uprobes.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 648f47553bff..27b596f14463 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -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;