From nobody Tue Dec 23 08:45:47 2025 Received: from mail-yw1-f201.google.com (mail-yw1-f201.google.com [209.85.128.201]) (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 E0DAF28DC1 for ; Tue, 6 Aug 2024 02:21:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722910889; cv=none; b=UM7/5PDn39dNDvnKEe0eIlmRt+MQGxKnsuy4zWZsf1F857tP7AVnW90s+j69VytiCEZENgrgPDMJMjUgAdY1koQK10v+fzBpzc3QZOaKdcFkx6upIXuYZ8tcd0EKPGt4MVqlwLAb77vX103YTbuQykAagfI8pNMiUS+N8ab5JC8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722910889; c=relaxed/simple; bh=gYr+IKanW7SO53Hh0FAwufRCBjhpyVN8/ZLbUUxhUqI=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=nRscTMuCh69NSlx+P29lLFoUI8y7ZJ+U2ZXMTKhr4j05HFCQd2R5s7no3dd0/IyWB9CBObhOw6GSw1okTFgB5vZATQgMEiUdtidKC9ApHxHPRBaIhMxplG3QaCX69dNSq0QoEYEp8Hb4jEox9fT4YQaujbQc+ohSe60vB1rZRtw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--yuzhao.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=KEMtGgpH; arc=none smtp.client-ip=209.85.128.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--yuzhao.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="KEMtGgpH" Received: by mail-yw1-f201.google.com with SMTP id 00721157ae682-65b985bb059so410457b3.2 for ; Mon, 05 Aug 2024 19:21:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1722910887; x=1723515687; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=Dz9+L9Nas5YdR+3aU4+X/tR5OCfJ0AKY3iAQMLv0S5k=; b=KEMtGgpHKPr1kCuqmks0+nESA+I99x+GCEQ8lD6u4tjp9zFJF0U2npuQZi9snCHJ3Y 9gQERoJJ3aL9XixKXAj3FkdCg0zI4di367gU7S6FKMglloK5I1P9iNUpZM4zHq5/xnxb LL49F9HEqzkqkayj9eEKkWckXZHjHHTXLhCWY8UYJ3RLiWP21Lw5N8cx0vThvgsfm99F vx2W5h9MLBkj6WEjQaGWlBehH+duLxDGRa0DGRddILVkNkgF5hM6+wJYw6Bjal9N5YJR HxPaSfn+oLmiWcB4Q+EDzbHcyKV9Aur8jymaYMyoARbILonDOcGtpu0wcz9lb52KQb2+ Gmyg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1722910887; x=1723515687; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Dz9+L9Nas5YdR+3aU4+X/tR5OCfJ0AKY3iAQMLv0S5k=; b=Psrp+2qJBxW3XwMYvsu/l3P885jbIYgDyU9saYHKYNjS5hCa7P/DcuLmelxDjPsRXY /Zrvt7oODj6S/RjY40Rl6Xyv5gCsSuE3PevjZc8080izAzY6mYV2ykget0KfVCJPyRme JrSfzhUzo76XSN4d8aewNxD+1ssHbDY6W2ix9Ys+EJ0LC6KdkcGfAU3JZS2fUb0i7PgV PpcUSKwE50c5GWUVU7KD7gYzZF97ckwzSJZi8xQeS6cL/NN3DBV7mWkZJmyFj8SDTbhN reGmn+aALzLDtzQ/tkEZlNkoHJkUXGe7hxT/dWc6p9mEYAIS9Gug+t3pY3oHT/oj81G4 2jBg== X-Forwarded-Encrypted: i=1; AJvYcCWS1dDW0Hru0TNT1D5nvJPoILbPwQOUUp539mUJ5+l81WyWj/+//SvOY7JFnxnopFy9VAqhpCLW1eMmnNQlCvlPXkNLwKN441p+trQN X-Gm-Message-State: AOJu0Yyf53esu2+/K0WthVzvWhn+XtdIEsEoG7e6z/yZlYeqYy/rJYvr tpgn/I65JXY1BBgSfnu2Sa489B8Ku/nRdtfZBqoZvQFokj+mAQJOriG69URa4ZwLqJsDagB4oa0 TgQ== X-Google-Smtp-Source: AGHT+IE5Ot4MCUehL2BALtzt0Nbbacrl8HCjMPwdvfemN8nL8qevC8oWRD8zmA2efNk4jGDFZ//D943lM9s= X-Received: from yuzhao2.bld.corp.google.com ([2a00:79e0:2e28:6:261c:802b:6b55:e09c]) (user=yuzhao job=sendgmr) by 2002:a05:690c:113:b0:648:3f93:61f2 with SMTP id 00721157ae682-689641a414emr5295867b3.6.1722910886865; Mon, 05 Aug 2024 19:21:26 -0700 (PDT) Date: Mon, 5 Aug 2024 20:21:13 -0600 In-Reply-To: <20240806022114.3320543-1-yuzhao@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240806022114.3320543-1-yuzhao@google.com> X-Mailer: git-send-email 2.46.0.rc2.264.g509ed76dc8-goog Message-ID: <20240806022114.3320543-4-yuzhao@google.com> Subject: [RFC PATCH 3/4] arm64: pause remote CPUs to update vmemmap From: Yu Zhao To: Catalin Marinas , Will Deacon Cc: Andrew Morton , David Rientjes , Douglas Anderson , Frank van der Linden , Mark Rutland , Muchun Song , Nanyong Sun , Yang Shi , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Yu Zhao Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Pause remote CPUs so that the local CPU can follow the proper BBM sequence to safely update the vmemmap mapping `struct page` areas. While updating the vmemmap, it is guaranteed that neither the local CPU nor the remote ones will access the `struct page` area being updated, and therefore they will not trigger kernel PFs. Signed-off-by: Yu Zhao --- arch/arm64/include/asm/pgalloc.h | 55 ++++++++++++++++++++++++++++++++ mm/hugetlb_vmemmap.c | 14 ++++++++ 2 files changed, 69 insertions(+) diff --git a/arch/arm64/include/asm/pgalloc.h b/arch/arm64/include/asm/pgal= loc.h index 8ff5f2a2579e..1af1aa34a351 100644 --- a/arch/arm64/include/asm/pgalloc.h +++ b/arch/arm64/include/asm/pgalloc.h @@ -12,6 +12,7 @@ #include #include #include +#include =20 #define __HAVE_ARCH_PGD_FREE #define __HAVE_ARCH_PUD_FREE @@ -137,4 +138,58 @@ pmd_populate(struct mm_struct *mm, pmd_t *pmdp, pgtabl= e_t ptep) __pmd_populate(pmdp, page_to_phys(ptep), PMD_TYPE_TABLE | PMD_TABLE_PXN); } =20 +#ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP + +#define vmemmap_update_lock vmemmap_update_lock +static inline void vmemmap_update_lock(void) +{ + cpus_read_lock(); +} + +#define vmemmap_update_unlock vmemmap_update_unlock +static inline void vmemmap_update_unlock(void) +{ + cpus_read_unlock(); +} + +#define vmemmap_update_pte vmemmap_update_pte +static inline void vmemmap_update_pte(unsigned long addr, pte_t *ptep, pte= _t pte) +{ + preempt_disable(); + pause_remote_cpus(); + + pte_clear(&init_mm, addr, ptep); + flush_tlb_kernel_range(addr, addr + PAGE_SIZE); + set_pte_at(&init_mm, addr, ptep, pte); + + resume_remote_cpus(); + preempt_enable(); +} + +#define vmemmap_update_pmd vmemmap_update_pmd +static inline void vmemmap_update_pmd(unsigned long addr, pmd_t *pmdp, pte= _t *ptep) +{ + preempt_disable(); + pause_remote_cpus(); + + pmd_clear(pmdp); + flush_tlb_kernel_range(addr, addr + PMD_SIZE); + pmd_populate_kernel(&init_mm, pmdp, ptep); + + resume_remote_cpus(); + preempt_enable(); +} + +#define vmemmap_flush_tlb_all vmemmap_flush_tlb_all +static inline void vmemmap_flush_tlb_all(void) +{ +} + +#define vmemmap_flush_tlb_range vmemmap_flush_tlb_range +static inline void vmemmap_flush_tlb_range(unsigned long start, unsigned l= ong end) +{ +} + +#endif /* CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP */ + #endif diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index 2dd92e58f304..893c73493d9c 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -46,6 +46,18 @@ struct vmemmap_remap_walk { unsigned long flags; }; =20 +#ifndef vmemmap_update_lock +static void vmemmap_update_lock(void) +{ +} +#endif + +#ifndef vmemmap_update_unlock +static void vmemmap_update_unlock(void) +{ +} +#endif + #ifndef vmemmap_update_pmd static inline void vmemmap_update_pmd(unsigned long addr, pmd_t *pmdp, pte_t *ptep) @@ -194,10 +206,12 @@ static int vmemmap_remap_range(unsigned long start, u= nsigned long end, =20 VM_BUG_ON(!PAGE_ALIGNED(start | end)); =20 + vmemmap_update_lock(); mmap_read_lock(&init_mm); ret =3D walk_page_range_novma(&init_mm, start, end, &vmemmap_remap_ops, NULL, walk); mmap_read_unlock(&init_mm); + vmemmap_update_unlock(); if (ret) return ret; =20 --=20 2.46.0.rc2.264.g509ed76dc8-goog