From:   Chih-En Lin <shiyn.lin@gmail.com>
To:     Andrew Morton <akpm@linux-foundation.org>,
        Qi Zheng <zhengqi.arch@bytedance.com>,
        David Hildenbrand <david@redhat.com>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        John Hubbard <jhubbard@nvidia.com>,
        Nadav Amit <namit@vmware.com>, Barry Song <baohua@kernel.org>
Cc:     Steven Rostedt <rostedt@goodmis.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Yang Shi <shy828301@gmail.com>, Peter Xu <peterx@redhat.com>,
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        Vincenzo Frascino <Vincenzo.Frascino@arm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Andy Lutomirski <luto@kernel.org>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        "Liam R. Howlett" <Liam.Howlett@Oracle.com>,
        Fenghua Yu <fenghua.yu@intel.com>,
        Andrei Vagin <avagin@gmail.com>,
        Barret Rhoden <brho@google.com>,
        Michal Hocko <mhocko@suse.com>,
        "Jason A. Donenfeld" <Jason@zx2c4.com>,
        Alexey Gladkov <legion@kernel.org>,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org,
        linux-perf-users@vger.kernel.org,
        Dinglan Peng <peng301@purdue.edu>,
        Pedro Fonseca <pfonseca@purdue.edu>,
        Jim Huang <jserv@ccns.ncku.edu.tw>,
        Huichun Feng <foxhoundsk.tw@gmail.com>,
        Chih-En Lin <shiyn.lin@gmail.com>
Subject: [PATCH v4 06/14] mm/ksm: Break COW PTE before modify shared PTE
Date:   Tue,  7 Feb 2023 11:51:31 +0800
Message-Id: <20230207035139.272707-7-shiyn.lin@gmail.com>
In-Reply-To: <20230207035139.272707-1-shiyn.lin@gmail.com>
References: <20230207035139.272707-1-shiyn.lin@gmail.com>
MIME-Version: 1.0
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Break COW PTE before merge the page that reside in COW-ed PTE.

Signed-off-by: Chih-En Lin <shiyn.lin@gmail.com>
---
 mm/ksm.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/ksm.c b/mm/ksm.c
index dd02780c387f..ce3887d3b04c 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1045,7 +1045,7 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
 			      pte_t *orig_pte)
 {
 	struct mm_struct *mm = vma->vm_mm;
-	DEFINE_PAGE_VMA_WALK(pvmw, page, vma, 0, 0);
+	DEFINE_PAGE_VMA_WALK(pvmw, page, vma, 0, PVMW_BREAK_COW_PTE);
 	int swapped;
 	int err = -EFAULT;
 	struct mmu_notifier_range range;
@@ -1163,6 +1163,8 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
 	barrier();
 	if (!pmd_present(pmde) || pmd_trans_huge(pmde))
 		goto out;
+	if (break_cow_pte(vma, pmd, addr))
+		goto out;
 
 	mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm, addr,
 				addr + PAGE_SIZE);
-- 
2.34.1