From nobody Fri Dec 19 17:01:25 2025 Received: from mail-pl1-f169.google.com (mail-pl1-f169.google.com [209.85.214.169]) (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 35A571CDA20 for ; Wed, 4 Sep 2024 08:41:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.169 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725439304; cv=none; b=UZwlrfpp+h1RvwkCMGNd2MfJOSW7ACZM29WJELHdXm7kDn/bpIR5or4CRlwWeJaw5KorALUC0KGYHFjhScpI/Md8bMdRM4z0xfdRHV9sOCviIx2ML7M0h+Pe+pwcljyoeJkpmphRR+P817+7gxucq205hX1QrWA/mlxnX89z0yg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725439304; c=relaxed/simple; bh=hDpOwgBOPPSAVs5qcIYRUt4zcDmO9dDuotmNaP9YlXc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=VlVJMy+/Z9DahPVqv4ydmHKN8bclAlOf8oo5Qi3mGsGBgMJ1rrOqJn0NPdOeEZ6g1x++rulFQTudoIGi/CqyUhZbv0orTp1smour+I9FEE7mWJgCsRaUVQnKWv5ynihUKEXOcCg30cpeUCa3Oi/AcqgH/KYBZ6Q6KtH3GmCtLPM= 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=hub1K39V; arc=none smtp.client-ip=209.85.214.169 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="hub1K39V" Received: by mail-pl1-f169.google.com with SMTP id d9443c01a7336-2068acc8a4fso21204755ad.1 for ; Wed, 04 Sep 2024 01:41:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1725439302; x=1726044102; 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=vHfOyy55HFvG/XxGZW1ra6nqYg449VLN9cHJI9/IEBs=; b=hub1K39VoAw3gViDaM9WmbKAbGh92ejNsayldik9Ype+Cx4Jp9xXs/o3eQGlhn8FuL sm58pkVMVyBBY8gBM3YWbpP/MSf7ZLDVJ8WSQZcWikFkvPWjczx+hJedc5YSqKUcdDp5 w8vlVC99nv2TqZGVa5CEBTgK8xn0F+GqNJWZK34Z81ZZNcGzO9Jg+iRnw8Z54ozqGsc+ xkMVzCP77jzpW1OKnbnXUfhmM/t6mhTgrtu75+1gYjY3gcYF5zSQH7oE7STQRJkwP9TN azaD9CiTkviyv2nxFHE1rAk1ek1dLG/Sh0PG3zsKYCaR95B3fpf7VFQ/aEJ7On3bGwCQ D2Rg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1725439302; x=1726044102; 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=vHfOyy55HFvG/XxGZW1ra6nqYg449VLN9cHJI9/IEBs=; b=XamsjWduUbTYOfxdFKo2uDn7G9Xtmikmie8Hv1iOnjVUcPMXHU72UQkhpS/rjRm5se Ew7qoCJm80PqE27wkiKoihkTCAG28hwv2ONzJ8hOX5ieuLqS+EM+QR1N2C8uVpmyV+mZ T+qXM5j/BH8mPvahCcCknIgf2r0Bv4qugydXq7nL687+jxpY/L4HIXzcElkuMahDzmuS S0wKnDnaKVPggtIbKRCns+B9fiCa9BQhWjHKXxY8QoPoIjBQ7oTyoTnejx0R5tNqGRN3 qgNG5lbbFUMYnlaLhqSTvrSPBLZvcCRNoFTgHQNz47496FmV1DRGkvnJlvp/YIrFm9NI fTSA== X-Gm-Message-State: AOJu0YxcljuXIedvpauvKbMQ7qpYORgQPUuUoL95AtL6Zw8YVeFmPV21 GLBkwh0M0qqpNPzTnRZ1CndsFtC+eFST2OJWo+ae6PXPQpA1zjBOXjWP4lwHRo0= X-Google-Smtp-Source: AGHT+IGlDE+bZkJMe3LtnR3dMefm4RFnOsn/qpiRzdld3O/wCPCkO6r/LjjSl6iGWtDIKmNPthI/eg== X-Received: by 2002:a17:902:b68b:b0:202:4a24:ee with SMTP id d9443c01a7336-2050c45e710mr147539585ad.55.1725439302519; Wed, 04 Sep 2024 01:41:42 -0700 (PDT) Received: from C02DW0BEMD6R.bytedance.net ([139.177.225.242]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-206ae95a51csm9414045ad.117.2024.09.04.01.41.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Sep 2024 01:41:42 -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 v3 09/14] mm: mremap: move_ptes() use pte_offset_map_rw_nolock() Date: Wed, 4 Sep 2024 16:40:17 +0800 Message-Id: <20240904084022.32728-10-zhengqi.arch@bytedance.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: <20240904084022.32728-1-zhengqi.arch@bytedance.com> References: <20240904084022.32728-1-zhengqi.arch@bytedance.com> 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 move_ptes(), we may modify the new_pte after acquiring the new_ptl, so convert it to using pte_offset_map_rw_nolock(). Since we may free the PTE page in retract_page_tables() without holding the read lock of mmap_lock, so we still need to do a pmd_same() check after holding the PTL. Signed-off-by: Qi Zheng --- mm/mremap.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/mm/mremap.c b/mm/mremap.c index 24712f8dbb6b5..16e54151395ad 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -143,6 +143,7 @@ static int move_ptes(struct vm_area_struct *vma, pmd_t = *old_pmd, spinlock_t *old_ptl, *new_ptl; bool force_flush =3D false; unsigned long len =3D old_end - old_addr; + pmd_t pmdval; int err =3D 0; =20 /* @@ -175,14 +176,29 @@ static int move_ptes(struct vm_area_struct *vma, pmd_= t *old_pmd, err =3D -EAGAIN; goto out; } - new_pte =3D pte_offset_map_nolock(mm, new_pmd, new_addr, &new_ptl); + /* + * Since we may free the PTE page in retract_page_tables() without + * holding the read lock of mmap_lock, so we still need to do a + * pmd_same() check after holding the PTL. + */ + new_pte =3D pte_offset_map_rw_nolock(mm, new_pmd, new_addr, &pmdval, + &new_ptl); if (!new_pte) { pte_unmap_unlock(old_pte, old_ptl); err =3D -EAGAIN; goto out; } - if (new_ptl !=3D old_ptl) + if (new_ptl !=3D old_ptl) { spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); + + if (unlikely(!pmd_same(pmdval, pmdp_get_lockless(new_pmd)))) { + pte_unmap_unlock(new_pte, new_ptl); + pte_unmap_unlock(old_pte, old_ptl); + err =3D -EAGAIN; + goto out; + } + } + flush_tlb_batched_pending(vma->vm_mm); arch_enter_lazy_mmu_mode(); =20 --=20 2.20.1