From nobody Fri Dec 19 17:01:24 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 291421CDFA3 for ; Wed, 4 Sep 2024 08:41:49 +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=1725439311; cv=none; b=bcq3MGD9rGfCEMgGKgjjLKJKV9TnWf/oo6PaKnqCmgtDJHhY3hUUJJ8WwpwyMqRbGFzDjDZG+n1+ccuqA/ewAwE4wen1MtjdcQ6ny4YlgoGGfPHjqd9viXkh2OIwyGCqEzD3ZqAwVqrNIEQcWgLQWMHBUKnRdtKkZKqvilhgpTs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725439311; c=relaxed/simple; bh=zVU5JZ4/ifmYtzZKes/SHFL4sJ0rbrE0x8fSa2fyEJU=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=oBpnqu+IQM3Z2z1eopTAQpLtAsDvWn2dhSMSHeilL0j8vxOxwE/icZtdhawD+t8kUVMnvQxeGLT0QvvBia6i0beAWS03ibyGTjuVwmUMX8k+sJjIkmkc/u6Jrxhta+isJ7K2FOlZVAri6RTx/21F0+A0gnof6Cg/mZhO0o9eYcI= 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=hAV1l7pp; 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="hAV1l7pp" Received: by mail-pl1-f169.google.com with SMTP id d9443c01a7336-20696938f86so13468105ad.3 for ; Wed, 04 Sep 2024 01:41:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1725439309; x=1726044109; 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=DklgHNcyYpWTok/ex913aKZBAOiPUnESXBkqa0TTMVk=; b=hAV1l7pp5zvXkfO+L/hBkHrbueUVLJOQpusLGWoAtbzlEqSR/zrTtPuEK/1BV0QBWU hc7TfzebAV2FVLT9PmfClLab4s2lYLNsw9O85CSFuBDele81ggwmUqtf/4ma1of+fB8l pEG2COE8DmgYFFXpnWkDIF5JaxLwoidCLQYDKdjd6edQlAS6/RbkfwQ5S6CBBF9T9oOs EF4Gd0tlTTsneGaClQtj4rWILgZm0fPwWbtIx4znj3FUMx4Xr/otVi0qqqqwRz95Cg+A Rdezyxa0uzqlHSdFIaydGwF0OfXGFiytV8Pmowk6R0if7w+JI+Wzi8/l5ppGk4KCA10i rJvw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1725439309; x=1726044109; 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=DklgHNcyYpWTok/ex913aKZBAOiPUnESXBkqa0TTMVk=; b=GeECGDPzsf3ZyANKL4eLkhE607rHUVRf2/wTv8aqph6aasFWt52bMWM+dlQYYkyzez bR3SdkafHiiu2Pr99DcynADKtscBuCCsRyDvxrH8fixeObX5DKmBvZv5N2GK/Psugrfw v3hgz/ed0tKhfBuZhIrxjT5TrPl9ng6wm+wZfPtJ9O+NK3lG7GhcuSgZ5H8SjaFLIUvl wPkGCCUEalGUNCzV5jkGTBKo5Bgz8CRv6mde51IOO1P1rkF28K7FIAAZEVGmD9pqpUpz T/1lyVLUehuty8SbZYJ8p4wr9FxZBksRyCCAfpiMmhPcBOFCSTL1mg59z1L3TdhpIjE/ ptAA== X-Gm-Message-State: AOJu0Yzd6RJj0Ry4FAUV++2rT7tAd4YMJvNsJXq28Nne7eHJq5YuSYCH UzvWu4zCmvE7vSS4hD0Ts7CPeKUlvVq5HeR+Te60qMNgNKfqKCwzLqA2oXA0W2Y= X-Google-Smtp-Source: AGHT+IErn+gfx0jNqN8oYReDzi5ALFGdG/LuObb3FXvUpU+trUkKEzs/YdM2MbdzLHq+FDgFhXw6+A== X-Received: by 2002:a17:902:d50a:b0:205:6c25:fe12 with SMTP id d9443c01a7336-2056c25ffb5mr96453155ad.34.1725439309345; Wed, 04 Sep 2024 01:41:49 -0700 (PDT) Received: from C02DW0BEMD6R.bytedance.net ([139.177.225.242]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-206ae95a51csm9414045ad.117.2024.09.04.01.41.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Sep 2024 01:41:49 -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 10/14] mm: page_vma_mapped_walk: map_pte() use pte_offset_map_rw_nolock() Date: Wed, 4 Sep 2024 16:40:18 +0800 Message-Id: <20240904084022.32728-11-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 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 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