From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8EA1E6453 for ; Tue, 22 Mar 2022 21:42:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 56E32C340F5; Tue, 22 Mar 2022 21:42:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1647985326; bh=Ggz33SJm+G5IlaykbrhNZ7fUyEpBzLe9xRoIA5YhLXc=; h=Date:To:From:In-Reply-To:Subject:From; b=rm9xtmJmEgVCqnlgZnbXdqcvs3ysN86UdsWn6J05jUxTY45VkW5jMEwBY1YTcw3iy K52fASLSV9xfl4n6tCwdBTOCdAarbUYTzAkdu4lt2q0qhqUzK5CCQ4IpUPwTHxuf6r qgGfFa4NmdnYCzL1gIttWPTpfjl/4ii8VoGowC44= Date: Tue, 22 Mar 2022 14:42:05 -0700 To: ziy@nvidia.com,rientjes@google.com,peterx@redhat.com,mike.kravetz@oracle.com,lars.persson@axis.com,kirill.shutemov@linux.intel.com,fam.zheng@bytedance.com,duanxiongchun@bytedance.com,axelrasmussen@google.com,songmuchun@bytedance.com,akpm@linux-foundation.org,patches@lists.linux.dev,linux-mm@kvack.org,mm-commits@vger.kernel.org,torvalds@linux-foundation.org,akpm@linux-foundation.org From: Andrew Morton In-Reply-To: <20220322143803.04a5e59a07e48284f196a2f9@linux-foundation.org> Subject: [patch 070/227] mm: shmem: fix missing cache flush in shmem_mfill_atomic_pte() Message-Id: <20220322214206.56E32C340F5@smtp.kernel.org> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: From: Muchun Song Subject: mm: shmem: fix missing cache flush in shmem_mfill_atomic_pte() userfaultfd calls shmem_mfill_atomic_pte() which does not do any cache flushing for the target page. Then the target page will be mapped to the user space with a different address (user address), which might have an alias issue with the kernel address used to copy the data from the user to. Insert flush_dcache_page() in non-zero-page case. And replace clear_highpage() with clear_user_highpage() which already considers the cache maintenance. Link: https://lkml.kernel.org/r/20220210123058.79206-6-songmuchun@bytedance.com Fixes: 8d1039634206 ("userfaultfd: shmem: add shmem_mfill_zeropage_pte for userfaultfd support") Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support") Signed-off-by: Muchun Song Reviewed-by: Mike Kravetz Cc: Axel Rasmussen Cc: David Rientjes Cc: Fam Zheng Cc: Kirill A. Shutemov Cc: Lars Persson Cc: Peter Xu Cc: Xiongchun Duan Cc: Zi Yan Signed-off-by: Andrew Morton --- mm/shmem.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/mm/shmem.c~mm-shmem-fix-missing-cache-flush-in-shmem_mfill_atomic_pte +++ a/mm/shmem.c @@ -2364,8 +2364,10 @@ int shmem_mfill_atomic_pte(struct mm_str /* don't free the page */ goto out_unacct_blocks; } + + flush_dcache_page(page); } else { /* ZEROPAGE */ - clear_highpage(page); + clear_user_highpage(page, dst_addr); } } else { page = *pagep; _