linux-kernel - [PATCH v7 4/4] uprobe: use FOLL_SPLIT_PMD instead of FOLL

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Message-ID: <20190625235325.2096441-5-songliubraving@fb.com>
Date:   Tue, 25 Jun 2019 16:53:25 -0700
From:   Song Liu <songliubraving@...com>
To:     <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>
CC:     <matthew.wilcox@...cle.com>, <kirill.shutemov@...ux.intel.com>,
        <peterz@...radead.org>, <oleg@...hat.com>, <rostedt@...dmis.org>,
        <kernel-team@...com>, <william.kucharski@...cle.com>,
        Song Liu <songliubraving@...com>
Subject: [PATCH v7 4/4] uprobe: use FOLL_SPLIT_PMD instead of FOLL_SPLIT

This patches uses newly added FOLL_SPLIT_PMD in uprobe. This enables easy
regroup of huge pmd after the uprobe is disabled (in next patch).

Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Signed-off-by: Song Liu <songliubraving@...com>
---
 kernel/events/uprobes.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index f7c61a1ef720..a20d7b43a056 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -153,7 +153,7 @@ 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,
 	};
@@ -165,8 +165,6 @@ 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 (!orig) {
 		err = mem_cgroup_try_charge(new_page, vma->vm_mm, GFP_KERNEL,
 					    &memcg, false);
@@ -483,7 +481,7 @@ 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;
 
-- 
2.17.1