From nobody Sat Feb 7 21:14:49 2026 Received: from mail-pf1-f172.google.com (mail-pf1-f172.google.com [209.85.210.172]) (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 8489E32A3C9 for ; Mon, 29 Dec 2025 14:31:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767018664; cv=none; b=FDgrIWNPMsEQqlfXsnhbjj2Lr0OmR5GZEjG02wegIBVwl5mP41gl1EKEYPPdLGodWG8lBTZTOj1/InOBfMIIKiCWl73YOk9LLtekUP0gofnSVCrgJxNz7GlkmsP8papAqoeRth8RkgNmJjbqjMoJouTgQOfRcfO6mx7GDQh/pxU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767018664; c=relaxed/simple; bh=lC6GEfxIGK/35lvrPF2qw5D86rHWEQ6C/lNcw05H+jI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Wz+D9O0c63a50/xGdRqxaeBZS4irHrozwpEjqFz34zWMl4fs6G0JaFDmSFexFkMYC5Y/hZIUx0OB2A6Gu8mooVI7wiup5mbTdwsEwlU5sBSCOtdQgRt6mY4jpnMGlSFYl6gFBfot5/tyHe1pjgSEHyoOi+52Z/Wf3HTuY7fFAVk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=gmail.com; arc=none smtp.client-ip=209.85.210.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-pf1-f172.google.com with SMTP id d2e1a72fcca58-7b8eff36e3bso14504963b3a.2 for ; Mon, 29 Dec 2025 06:31:02 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1767018662; x=1767623462; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=foHDr6tTVVg2N+oq2ubI3TwM6NJy7Osy+6nFP/DCYQ8=; b=FMwA788qojJwIbFWis6ViQtOhnffZNsIkuFEUFFdKChXxKjtHc5bIcZVvoWptyn/Y2 YxO42bazjfaZx746TyY7I/pIft+gW2Hmz1r0aAy/RcIa0fQ/VqYAfYb7zbHGhtMoShEw 6BEBRzlj2xQ4WgvYphV9kpNRWEz7qrbJiys29rB8FynxRHgW/GIRfsxtwixjWHEhQkNW Lv3H15q4B5HBmseYKVaj87GfukORSiqzfwkavjNygP13bXuC+D32dU/d/FTBw+IM/6i+ /odgNXuqGiMlmkT46M2vW77b9LuMyGtLWTf5ZljwomLfsQ9qAhzmP1WsvTcnJNl1sx67 jajQ== X-Forwarded-Encrypted: i=1; AJvYcCWjwC8+Nck35KeYE/bhLT45hEf0Hlk3i+IDuvaaIKMGmIw0b/es4Al6v9A4dQ7uIulepTAsBarSYgej1BE=@vger.kernel.org X-Gm-Message-State: AOJu0YxaXsUeeLj4A+CU8zNKIcwl+DwLCRZWsAMfIfBqzUf/gKPvK0st Ll2h4w1Nrk3glKKbtKg3lFrK8t7Z5NPNs4ez3PY4RHOVToXYQMLnfimI X-Gm-Gg: AY/fxX7XKdC7p5ppqG/NURbN/8XEj5AQ0sosjGBuQ2/KDyxmiQr35BxYDNUPfyWq8p7 Xpp2CFPZIGmoAkt8fo6vNc2RxeTDHBrsSPS7gl8jflyYcV3N73zgHNq+LtLtuDfXkhcT7pIVWuv tDFL99dh20pivg/7VE4UAmradV4LFOly8jrEKnivvxw4R6rktrpqyZg0+QP68j1Xc42QZdRRPSE RAoUnyKBAfeH62rhWLPxuLGDQBd8v/OHq9PIcuPP/QFU9XNHaaTxhuwlH4gGIzQ8+Ok+5LXj0a3 NN+4NyL9ylIPNOv7EXB3pjliPHm4xkB9WQQxOrH3rYwp6N4KIRu3b+FkewHjJm5kbFhC+39CCBs f7wg+NFjjqX6fzKm6PlLGC5gCVS2kVxEZ2k7CiEACPcES6feJWSreAHy6BRkbW4aiT7AzMDE6Ih erP2c5gjp0TWYz+b5iZu3e X-Google-Smtp-Source: AGHT+IEcRpszq5Kq79VNLMGams7x9wFNNmMmBbYeukt6SbJFbwCYZtO3VxeJZmswaHVyyAPRvGA8Bg== X-Received: by 2002:a05:6a00:4514:b0:7f7:4a39:55cd with SMTP id d2e1a72fcca58-7ff6178be74mr27982951b3a.0.1767018661690; Mon, 29 Dec 2025 06:31:01 -0800 (PST) Received: from EBJ9932692.tcent.cn ([103.88.46.167]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7ff7dfac28fsm29705159b3a.32.2025.12.29.06.30.52 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 29 Dec 2025 06:31:01 -0800 (PST) From: Lance Yang To: akpm@linux-foundation.org Cc: will@kernel.org, aneesh.kumar@kernel.org, npiggin@gmail.com, peterz@infradead.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, arnd@arndb.de, david@kernel.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, ioworker0@gmail.com, shy828301@gmail.com, riel@surriel.com, jannh@google.com, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Lance Yang Subject: [PATCH RESEND v1 1/3] mm/tlb: allow architectures to skip redundant TLB sync IPIs Date: Mon, 29 Dec 2025 22:30:31 +0800 Message-ID: <20251229143038.73315-2-lance.yang@linux.dev> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20251229143038.73315-1-lance.yang@linux.dev> References: <20251229143038.73315-1-lance.yang@linux.dev> 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" From: Lance Yang When unsharing hugetlb PMD page tables, we currently send two IPIs: one for TLB invalidation, and another to synchronize with concurrent GUP-fast walkers. However, if the TLB flush already reaches all CPUs, the second IPI is redundant. GUP-fast runs with IRQs disabled, so when the TLB flush IPI completes, any concurrent GUP-fast must have finished. Add tlb_table_flush_implies_ipi_broadcast() to let architectures indicate their TLB flush provides full synchronization, enabling the redundant IPI to be skipped. Suggested-by: David Hildenbrand (Red Hat) Signed-off-by: Lance Yang --- include/asm-generic/tlb.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h index 4d679d2a206b..e8d99b5e831f 100644 --- a/include/asm-generic/tlb.h +++ b/include/asm-generic/tlb.h @@ -261,6 +261,20 @@ static inline void tlb_remove_table_sync_one(void) { } =20 #endif /* CONFIG_MMU_GATHER_RCU_TABLE_FREE */ =20 +/* + * Architectures can override if their TLB flush already broadcasts IPIs t= o all + * CPUs when freeing or unsharing page tables. + * + * Return true only when the flush guarantees: + * - IPIs reach all CPUs with potentially stale paging-structure cache ent= ries + * - Synchronization with IRQ-disabled code like GUP-fast + */ +#ifndef tlb_table_flush_implies_ipi_broadcast +static inline bool tlb_table_flush_implies_ipi_broadcast(void) +{ + return false; +} +#endif =20 #ifndef CONFIG_MMU_GATHER_NO_GATHER /* --=20 2.49.0