From nobody Mon Feb 9 17:25:14 2026 Received: from mail-pf1-f175.google.com (mail-pf1-f175.google.com [209.85.210.175]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B8F3E149DFD for ; Thu, 22 Aug 2024 07:14:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.175 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724310865; cv=none; b=HzJHw5UfSGOBasmfkJH5wDdgWoTKNTq8SEkIoAQtDVsv0oy0+idumCWdUvkTYgfapMI9NE4AQLrCAMJzMgLJdX0fRBiO/wyeD/yTslD29tmOCBqSGYtwkcxLPeBmlPjWhYQEf+Su4vRt2DF1AqnbctpBiu3hxfd1Q5RA7dfE01U= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724310865; c=relaxed/simple; bh=zGFC12VfR2Lu98Id6HwQmHSrNI/SYJwpzP6u5eIGDC8=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=fFwottnYIOPXPQCk/ZwmFewLbvVOFrkDEAX/nSyuvmwUJcZi0WT30CfmsVtKqwfQqCt3Yd7RP0oATBfTjRX9m2BAXJdK5zMcFkXqcARZ1HsaGcUuxvi8xiEmMXXuJQ+gpnrAII5u6jU6uyDmCNYvBinkXfFbc+HJ7xQosJXr+ZA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=bytedance.com; spf=pass smtp.mailfrom=bytedance.com; dkim=pass (2048-bit key) header.d=bytedance.com header.i=@bytedance.com header.b=MUbnGPUw; arc=none smtp.client-ip=209.85.210.175 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=bytedance.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bytedance.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bytedance.com header.i=@bytedance.com header.b="MUbnGPUw" Received: by mail-pf1-f175.google.com with SMTP id d2e1a72fcca58-7142a93ea9cso394349b3a.3 for ; Thu, 22 Aug 2024 00:14:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1724310863; x=1724915663; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=YTJMrM+GLhYLeZwUuiK6dImcBAbTGjqYt196yQPATUA=; b=MUbnGPUwopBF0lbcogAfE1boCRWCwqj/TWznuIZBqg2NBazuHglqRR2JVgKXVS5ZpY 32w7S9cMkQTvyLfprxeMLC23wItX6kNzz+gxVddOu/6vnkqNcJ5Y9efbZLavwCVMPJsC OcuvTHPMbiiAtatCHdJE0NCVe/8aFQ0C4I12dZxJwTSNJmhVCyGqzVqY60Qft1rYUuwz 10exixL6x/rjS/X4mlyzefKDVDjiE3lJsWA/8oTp5+zVSz/2YGix/zEO8/XEUhBGHva9 yNWP6WBHF79+5c2xVMuYt130tmaHj5dT42D5qXYyfoOteDo0Rf961v3slFJm7NYyxxYp noCQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1724310863; x=1724915663; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=YTJMrM+GLhYLeZwUuiK6dImcBAbTGjqYt196yQPATUA=; b=mfstBvW5rnkmOEJAVu6Rwm+FZCJFm4og6BibEHii3QbqnzdT1saaE+W9Hfj5qbmIld jp2F5i+iW8CdI/Qy1BOqHH3isVYJVuxZcHPy+vmis2FacnfIuSvdavG0aSr2sOno59IY UgWhYXvKk2hz1WG2oqi64Pml2nOwFwafNbWjYdM8+7vwPM+xIZuSoZ50yMLfZVYTV/bi bayLfbR4nBQzvf7YzUV9H4afwHXHr4QZuZXJjTp25lYg15RsZh+LGnmBIdFeBXiZWHgM uma6ijfoap/aR1zPWXgwLz6Ns/JBkmKSJ/7cnH0YMnPCoTHqiGDec02OMKxjYAUr+n/F 7hEA== X-Gm-Message-State: AOJu0YxSjOii6sp8wjWHrJg7un6ecur5eHnnW4krc7RRSzYSnfEO/Rsh ahLjZS17oVFugm2OgMgtUvcE8HFDrFwhGeojtHU5e3jrab6xa55gxOTpdkh1R4Y= X-Google-Smtp-Source: AGHT+IEJaUpX6CQIEutPHebqIOZXfyMaKxdLW1UElMR3gb10gY3PgzFG7UEaK+UwdtskMN8KUpfIGw== X-Received: by 2002:a05:6a00:cd4:b0:714:1bce:913a with SMTP id d2e1a72fcca58-7142356e960mr5852557b3a.21.1724310862916; Thu, 22 Aug 2024 00:14:22 -0700 (PDT) Received: from C02DW0BEMD6R.bytedance.net ([240e:473:c90:f96:d029:ea8a:4e6d:d272]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-7cd9ac994a3sm695095a12.16.2024.08.22.00.14.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Aug 2024 00:14:22 -0700 (PDT) From: Qi Zheng To: david@redhat.com, hughd@google.com, willy@infradead.org, muchun.song@linux.dev, vbabka@kernel.org, akpm@linux-foundation.org, rppt@kernel.org, vishal.moola@gmail.com, peterx@redhat.com, ryan.roberts@arm.com, christophe.leroy2@cs-soprasteria.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, Qi Zheng Subject: [PATCH v2 06/14] mm: handle_pte_fault() use pte_offset_map_rw_nolock() Date: Thu, 22 Aug 2024 15:13:21 +0800 Message-Id: <5acabedfae7ded01b075960b4a91f2e15b4d76b5.1724310149.git.zhengqi.arch@bytedance.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" In handle_pte_fault(), we may modify the vmf->pte after acquiring the vmf->ptl, so convert it to using pte_offset_map_rw_nolock(). But since we will do the pte_same() check, so there is no need to get pmdval to do pmd_same() check, just pass a dummy variable to it. Signed-off-by: Qi Zheng Acked-by: David Hildenbrand Reviewed-by: Muchun Song --- mm/memory.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 93c0c25433d02..7b6071a0e21e2 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5499,14 +5499,22 @@ static vm_fault_t handle_pte_fault(struct vm_fault = *vmf) vmf->pte =3D NULL; vmf->flags &=3D ~FAULT_FLAG_ORIG_PTE_VALID; } else { + pmd_t dummy_pmdval; + /* * A regular pmd is established and it can't morph into a huge * pmd by anon khugepaged, since that takes mmap_lock in write * mode; but shmem or file collapse to THP could still morph * it into a huge pmd: just retry later if so. + * + * Use the maywrite version to indicate that vmf->pte will be + * modified, but since we will use pte_same() to detect the + * change of the pte entry, there is no need to get pmdval, so + * just pass a dummy variable to it. */ - vmf->pte =3D pte_offset_map_nolock(vmf->vma->vm_mm, vmf->pmd, - vmf->address, &vmf->ptl); + vmf->pte =3D pte_offset_map_rw_nolock(vmf->vma->vm_mm, vmf->pmd, + vmf->address, &dummy_pmdval, + &vmf->ptl); if (unlikely(!vmf->pte)) return 0; vmf->orig_pte =3D ptep_get_lockless(vmf->pte); --=20 2.20.1