From nobody Mon Feb 9 19:30:24 2026 Received: from mail-oi1-f178.google.com (mail-oi1-f178.google.com [209.85.167.178]) (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 0C1D11885A2 for ; Thu, 22 Aug 2024 07:14:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.178 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724310887; cv=none; b=pkdhGgvLTOJoxRL/h9C67sOVuVVtWPucaOoNcz+jNgIacJBQc3069IBbUvz5PyesBclkHPRkbuieQsxQzx467KG1Bsxy9Ih3ZWA6J81Qj86BWHxg0dB6fKpVvw5UjazK26M0G3lMgpfy17gLfAOySjiSbzEqyY+NU5idtxAk8Ps= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724310887; c=relaxed/simple; bh=NDVt8UFk+zbfrRMfMiJ0eEKdBEzxM75Y5QRnhcSFNmY=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=c4nrUdLEq1WxLgbdwLDAv3RSh6mgp74xIvo1T9D+ScuEC0iXLFy0pprX2dhQHNno+9MUN1+Q98xhYJA59OTOa7BnazwcUQAJJGb4vQTRWnxC+YZBwKU2zjka+/dyWcOZaOHqcAMKLSFvnpdnYb1fSVyDRMXc10GBO8Al0258ESE= 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=BSUNtw57; arc=none smtp.client-ip=209.85.167.178 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="BSUNtw57" Received: by mail-oi1-f178.google.com with SMTP id 5614622812f47-3db2315d7ceso298595b6e.1 for ; Thu, 22 Aug 2024 00:14:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1724310885; x=1724915685; 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=Crbz/R3rJcbpbcovfp9fh4ozsAEMZSaAxrx7zvZfRRw=; b=BSUNtw576jvEjIJoJ9xgAAwGsuSieh8ylg8a5IgnAubAVyCc2jyMnkLhSE+C4uBAow TegzwyVMOSAWIwytdourj9Qu8i4ywKkofc+PPJKX6G89ErjdsjXwlxP1UIO/oBQc0+30 WaOGPr4B9MkyehQJ0A2Zf82WELGkIjjL2rGNQ3VPTa7nTzNdQa9D53poRsiQKn7eEk3R np3iOayYoPW6CJ4KUz2R6EkqQtHCuhn22jIvS9bUt2lALzUxHFu+Kp/HU2o1Wm9VcDE0 Ytx7+jQLbq7T9SfpIvOUHi296FCCM+vsTPdolPwZVJIKAqezQkSF+mDFYHqt4jCpyieL KdiQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1724310885; x=1724915685; 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=Crbz/R3rJcbpbcovfp9fh4ozsAEMZSaAxrx7zvZfRRw=; b=T84h6pXSkv1gNHTxMT87VtbYkkS3R+DixNp60tDLYZ0NPsOiOfmdtx1j9JVMGCrQs5 2Wm9WQkfFD3Cx5w+fi2gPfFLqf8230YXVVlE9+gebxo8bjbpzC2cWZ0exPF7YXW/aCA2 DYL6c9ZCDWInYQxqjWpuJkHzsp2iX5lmny4ju+qop8P3cm+vg8ByuLsb/P9jiE5BjM2B j5aWb61Cwlar4+5ORuhWOqq1R7Jw8Tl3sd6Gvl9RejTrddl/5XZGZ+20m8min68LjeDe sg02Rz4NyQ/JCShB9fVo1rgIt8SW3Rbfrmog8WLZbtjcf94OK0T/FjVIYkWnJRNNzN8D he2A== X-Gm-Message-State: AOJu0YxNMWaMhkBfSB595SF6XEiWF0uVBncwIN4gR3edo8Spx699bPAE MexhO3t9B3YgGphxY51LFbSzGDOI0HW4MOMQbvijahyKe+aVSbB/kGtaNf5V0vo= X-Google-Smtp-Source: AGHT+IF73IAzwqsx0nomJCVJryAV7cndKc0EgZ0+2TYoDy25bfQlq+9JSwXFUBQmZZcxXSkt111lxw== X-Received: by 2002:a05:6808:d46:b0:3d9:29c1:be5c with SMTP id 5614622812f47-3de194fbf2bmr5329807b6e.12.1724310885053; Thu, 22 Aug 2024 00:14:45 -0700 (PDT) Received: from C02DW0BEMD6R.bytedance.net ([240e:473:c90:f96:d029:ea8a:4e6d:d272]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-7cd9ac994a3sm695095a12.16.2024.08.22.00.14.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Aug 2024 00:14:44 -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 10/14] mm: page_vma_mapped_walk: map_pte() use pte_offset_map_rw_nolock() Date: Thu, 22 Aug 2024 15:13:25 +0800 Message-Id: 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 the caller of map_pte(), we may modify the pvmw->pte after acquiring the pvmw->ptl, so convert it to using pte_offset_map_rw_nolock(). At this time, the write lock of mmap_lock is not held, and the pte_same() check is not performed after the pvmw->ptl held, so we should get pmdval and do pmd_same() check to ensure the stability of pvmw->pmd. Signed-off-by: Qi Zheng --- mm/page_vma_mapped.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c index ae5cc42aa2087..f1d73fd448708 100644 --- a/mm/page_vma_mapped.c +++ b/mm/page_vma_mapped.c @@ -13,9 +13,11 @@ static inline bool not_found(struct page_vma_mapped_walk= *pvmw) return false; } =20 -static bool map_pte(struct page_vma_mapped_walk *pvmw, spinlock_t **ptlp) +static bool map_pte(struct page_vma_mapped_walk *pvmw, pmd_t *pmdvalp, + spinlock_t **ptlp) { pte_t ptent; + pmd_t pmdval; =20 if (pvmw->flags & PVMW_SYNC) { /* Use the stricter lookup */ @@ -25,6 +27,7 @@ static bool map_pte(struct page_vma_mapped_walk *pvmw, sp= inlock_t **ptlp) return !!pvmw->pte; } =20 +again: /* * It is important to return the ptl corresponding to pte, * in case *pvmw->pmd changes underneath us; so we need to @@ -32,10 +35,11 @@ static bool map_pte(struct page_vma_mapped_walk *pvmw, = spinlock_t **ptlp) * proceeds to loop over next ptes, and finds a match later. * Though, in most cases, page lock already protects this. */ - pvmw->pte =3D pte_offset_map_nolock(pvmw->vma->vm_mm, pvmw->pmd, - pvmw->address, ptlp); + pvmw->pte =3D pte_offset_map_rw_nolock(pvmw->vma->vm_mm, pvmw->pmd, + pvmw->address, &pmdval, ptlp); if (!pvmw->pte) return false; + *pmdvalp =3D pmdval; =20 ptent =3D ptep_get(pvmw->pte); =20 @@ -69,6 +73,12 @@ static bool map_pte(struct page_vma_mapped_walk *pvmw, s= pinlock_t **ptlp) } pvmw->ptl =3D *ptlp; spin_lock(pvmw->ptl); + + if (unlikely(!pmd_same(pmdval, pmdp_get_lockless(pvmw->pmd)))) { + spin_unlock(pvmw->ptl); + goto again; + } + return true; } =20 @@ -278,7 +288,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *= pvmw) step_forward(pvmw, PMD_SIZE); continue; } - if (!map_pte(pvmw, &ptl)) { + if (!map_pte(pvmw, &pmde, &ptl)) { if (!pvmw->pte) goto restart; goto next_pte; @@ -307,6 +317,12 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk = *pvmw) if (!pvmw->ptl) { pvmw->ptl =3D ptl; spin_lock(pvmw->ptl); + if (unlikely(!pmd_same(pmde, pmdp_get_lockless(pvmw->pmd)))) { + pte_unmap_unlock(pvmw->pte, pvmw->ptl); + pvmw->ptl =3D NULL; + pvmw->pte =3D NULL; + goto restart; + } } goto this_pte; } while (pvmw->address < end); --=20 2.20.1