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Sun, 18 May 2025 21:38:58 -0700 (PDT) From: Barry Song <21cnbao@gmail.com> To: ryncsn@gmail.com Cc: akpm@linux-foundation.org, baohua@kernel.org, baolin.wang@linux.alibaba.com, bhe@redhat.com, chrisl@kernel.org, david@redhat.com, hannes@cmpxchg.org, hughd@google.com, kaleshsingh@google.com, kasong@tencent.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, nphamcs@gmail.com, ryan.roberts@arm.com, shikemeng@huaweicloud.com, tim.c.chen@linux.intel.com, willy@infradead.org, ying.huang@linux.alibaba.com, yosryahmed@google.com Subject: [PATCH 05/28] mm, swap: sanitize swap cache lookup convention Date: Mon, 19 May 2025 16:38:47 +1200 Message-Id: <20250519043847.1806-1-21cnbao@gmail.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20250514201729.48420-6-ryncsn@gmail.com> References: <20250514201729.48420-6-ryncsn@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit > From: Kairui Song > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c > index e5a0db7f3331..5b4f01aecf35 100644 > --- a/mm/userfaultfd.c > +++ b/mm/userfaultfd.c > @@ -1409,6 +1409,10 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, > goto retry; > } > } > + if (!folio_swap_contains(src_folio, entry)) { > + err = -EBUSY; > + goto out; > + } It seems we don't need this. In move_swap_pte(), we have been checking pte pages are stable: if (!is_pte_pages_stable(dst_pte, src_pte, orig_dst_pte, orig_src_pte, dst_pmd, dst_pmdval)) { double_pt_unlock(dst_ptl, src_ptl); return -EAGAIN; } Also, -EBUSY is somehow incorrect error code. > err = move_swap_pte(mm, dst_vma, dst_addr, src_addr, dst_pte, src_pte, > orig_dst_pte, orig_src_pte, dst_pmd, dst_pmdval, > dst_ptl, src_ptl, src_folio); > Thanks Barry