From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-187.mta1.migadu.com (out-187.mta1.migadu.com [95.215.58.187]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 90AC217BEBF for ; Mon, 15 Sep 2025 04:24:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.187 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757910290; cv=none; b=USTgJLE3C04FBPKD+06nlN6WKx0ib+wgdMsUqzZ1GtHjpRsyOdLIpeg/W+M38dRSTQEb7WtXbUY3S4Fa851CYb41368BJsd18tfOB8l/69H4+aDw9f0MTHqm0oXPEMfjGxsxfLnA1PsKzKyUijUYroMf5N2aSDq08gLSOMgPRaw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757910290; c=relaxed/simple; bh=PASy16iu6y2521ZrmfszjgkkjV83uibEcXOvOHT3GS4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=YwQpknrluM3oIPIniwX4ePI3MQDnh7Wp/KB5ocTfR3atZq5qmzgwTTH8itYghvXOTQH5w1odIaU5VR+7/Z2+LcW6D3dN/Rj7qhme9vp1hpeTt1ajbyzbCbCYllphO+z4krKxxTjglfFq8l19fykVRMVSxzzSxtwUqW6iGi91Qi8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=uER8sLex; arc=none smtp.client-ip=95.215.58.187 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="uER8sLex" Message-ID: <434ecc5a-3aec-4381-8477-8a7d09220051@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1757910284; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ehnEhT9IwpoRpyq7W3B9rNarRzhELO0M7YbeeCPAQMM=; b=uER8sLexksdHO9XbHYOptdkH/NAAPFYOzOUJVgerwDt80blqcBLHvrqWNDz7+G4w8LzTlA GC+tt+uJ0Ivobr6/GHjNDSAKDmfu6l3H7x9psd+Z+emAk+uqhUL/8aSBrVIEJqT0MZ1zCL nTBGcgAtpfaGLLHgFP2UZ8NknmN9Jyk= Date: Mon, 15 Sep 2025 12:24:19 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH mm-new 2/3] mm: clean up and expose is_guard_pte_marker() Content-Language: en-US To: Dev Jain Cc: ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, baohua@kernel.org, ioworker0@gmail.com, lorenzo.stoakes@oracle.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Kairui Song , akpm@linux-foundation.org, david@redhat.com References: <20250914143547.27687-1-lance.yang@linux.dev> <20250914143547.27687-3-lance.yang@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Lance Yang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 2025/9/15 00:38, Dev Jain wrote: > > On 14/09/25 8:05 pm, Lance Yang wrote: >> From: Lance Yang >> >> is_guard_pte_marker() performs a redundant check because it calls both >> is_pte_marker() and is_guard_swp_entry(), both of which internally check >> for a PTE marker. >> >> is_guard_pte_marker() >>   |- is_pte_marker() >>   |   `- is_pte_marker_entry()  // First check >>   `- is_guard_swp_entry() >>       `- is_pte_marker_entry()  // Second, redundant check >> >> While a modern compiler could likely optimize this away, let's have clean >> code and not rely on it ;) >> >> Also, make it available for hugepage collapsing code. > > The movement of the code should be merged with the next patch. Thanks for the suggestion ;) I'd prefer to keep them as separate patches to make them easier to review, if that's okay. Cheers, Lance > >> >> Cc: Kairui Song >> Signed-off-by: Lance Yang >> --- >>   include/linux/swapops.h | 6 ++++++ >>   mm/madvise.c            | 6 ------ >>   2 files changed, 6 insertions(+), 6 deletions(-) >> >> diff --git a/include/linux/swapops.h b/include/linux/swapops.h >> index 59c5889a4d54..7f5684fa043b 100644 >> --- a/include/linux/swapops.h >> +++ b/include/linux/swapops.h >> @@ -469,6 +469,12 @@ static inline int is_guard_swp_entry(swp_entry_t >> entry) >>           (pte_marker_get(entry) & PTE_MARKER_GUARD); >>   } >> +static inline bool is_guard_pte_marker(pte_t ptent) >> +{ >> +    return is_swap_pte(ptent) && >> +           is_guard_swp_entry(pte_to_swp_entry(ptent)); >> +} >> + >>   /* >>    * This is a special version to check pte_none() just to cover the >> case when >>    * the pte is a pte marker.  It existed because in many cases the >> pte marker >> diff --git a/mm/madvise.c b/mm/madvise.c >> index 35ed4ab0d7c5..bd46e6788fac 100644 >> --- a/mm/madvise.c >> +++ b/mm/madvise.c >> @@ -1069,12 +1069,6 @@ static bool is_valid_guard_vma(struct >> vm_area_struct *vma, bool allow_locked) >>       return !(vma->vm_flags & disallowed); >>   } >> -static bool is_guard_pte_marker(pte_t ptent) >> -{ >> -    return is_pte_marker(ptent) && >> -        is_guard_swp_entry(pte_to_swp_entry(ptent)); >> -} >> - >>   static int guard_install_pud_entry(pud_t *pud, unsigned long addr, >>                      unsigned long next, struct mm_walk *walk) >>   {