From nobody Sun Sep 14 08:23:08 2025 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id B1EEE3002BC; Thu, 4 Sep 2025 12:58:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756990737; cv=none; b=LEKBXysrX9Y7H7x5wROdcnsLYyk7oNJ1RiIDNUf8DoFxJaXEnatvcvVnRc0DCTpIGJLmz2v94KxnegP5FVamsYEm0SDiNWwEPPTGW8gRTnesv7ofEaGU67f045dPGS1B8W5JhBHJeH6s79OzSFN2UyKV/rJwFLc6hhhj4MpKpao= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756990737; c=relaxed/simple; bh=eUDKAdZqgvs0HKckrnQ5CW9DnGDWJQkBfjxqaWum9qM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=FoIwUqByaIYQI7asjWB4RD3wXWKo2ujTlxRYImRIDrxIW5Hz0gKX7HpXdfxU9ZCtKEXaxSwy37s34RYAGQ7GGFqYYnRrWHmJIJ9IRUvTSvWcLvW3WRdX/VN+B3+AjUjz0LE6ANYF4/NpKNCCNN5awyDBzlfjqfe92rJkKFE8RvM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A725E2F28; Thu, 4 Sep 2025 05:58:46 -0700 (PDT) Received: from e123572-lin.arm.com (e123572-lin.cambridge.arm.com [10.1.194.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 757883F6A8; Thu, 4 Sep 2025 05:58:50 -0700 (PDT) From: Kevin Brodsky To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , Alexander Gordeev , Andreas Larsson , Andrew Morton , Boris Ostrovsky , Borislav Petkov , Catalin Marinas , Christophe Leroy , Dave Hansen , David Hildenbrand , "David S. Miller" , "H. Peter Anvin" , Ingo Molnar , Jann Horn , Juergen Gross , "Liam R. Howlett" , Lorenzo Stoakes , Madhavan Srinivasan , Michael Ellerman , Michal Hocko , Mike Rapoport , Nicholas Piggin , Peter Zijlstra , Ryan Roberts , Suren Baghdasaryan , Thomas Gleixner , Vlastimil Babka , Will Deacon , linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org, xen-devel@lists.xenproject.org Subject: [PATCH 7/7] mm: update lazy_mmu documentation Date: Thu, 4 Sep 2025 13:57:36 +0100 Message-ID: <20250904125736.3918646-8-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20250904125736.3918646-1-kevin.brodsky@arm.com> References: <20250904125736.3918646-1-kevin.brodsky@arm.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" We now support nested lazy_mmu sections on all architectures implementing the API. Update the API comment accordingly. Signed-off-by: Kevin Brodsky Acked-by: Mike Rapoport (Microsoft) --- include/linux/pgtable.h | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index 6932c8e344ab..be0f059beb4d 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -228,8 +228,18 @@ static inline int pmd_dirty(pmd_t pmd) * of the lazy mode. So the implementation must assume preemption may be e= nabled * and cpu migration is possible; it must take steps to be robust against = this. * (In practice, for user PTE updates, the appropriate page table lock(s) = are - * held, but for kernel PTE updates, no lock is held). Nesting is not perm= itted - * and the mode cannot be used in interrupt context. + * held, but for kernel PTE updates, no lock is held). The mode cannot be = used + * in interrupt context. + * + * Calls may be nested: an arch_{enter,leave}_lazy_mmu_mode() pair may be = called + * while the lazy MMU mode has already been enabled. An implementation sho= uld + * handle this using the state returned by enter() and taken by the matchi= ng + * leave() call; the LAZY_MMU_{DEFAULT,NESTED} flags can be used to indica= te + * whether this enter/leave pair is nested inside another or not. (It is u= p to + * the implementation to track whether the lazy MMU mode is enabled at any= point + * in time.) The expectation is that leave() will flush any batched state + * unconditionally, but only leave the lazy MMU mode if the passed state i= s not + * LAZY_MMU_NESTED. */ #ifndef __HAVE_ARCH_ENTER_LAZY_MMU_MODE typedef int lazy_mmu_state_t; --=20 2.47.0