From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 2F514155325 for ; Mon, 1 Jul 2024 08:51:03 +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=1719823865; cv=none; b=chpctfWy3DQOXIhl9Q1qDvfEpBU2f0Iuqva0QuP1PA5+7fU+MZXIkTMKbL7JMQGgJzgucaPAMDFBepGgziCFzcieg3uSF+kZ+SEcaAikld9FNQ8ztYVt4soyLOzEM61o8IE7JMvxf7HDAaT/zUqA8xS1aXp72S1cJm2NeRBMIe4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719823865; c=relaxed/simple; bh=ADeFDTrQyuXrodrUXFPne8GrrYXJRrCWVe3GARiGF/o=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=AKS41izJ1gEj3IRrwORNuLRVuarX4WQF9eFO7/j8ctsMwNyI53i6lP0Ef82jFJW4/DxdUhiEP9w98mxsCVeZTCxEasrB5wRDx5uZ52754Mi6EpY5ZL3IiMB1sT5W2giSy2op0RPs1km742+JVU1VwzTMZ/G8FZfEKNlvtUOscH4= 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 9B1B4339; Mon, 1 Jul 2024 01:51:27 -0700 (PDT) Received: from [10.57.72.41] (unknown [10.57.72.41]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 37FAD3F766; Mon, 1 Jul 2024 01:51:01 -0700 (PDT) Message-ID: <6f68fb9d-3039-4e38-bc08-44948a1dae4d@arm.com> Date: Mon, 1 Jul 2024 09:50:59 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] support "THPeligible" semantics for mTHP with anonymous shmem Content-Language: en-GB To: David Hildenbrand , Baolin Wang , Bang Li , hughd@google.com, akpm@linux-foundation.org Cc: wangkefeng.wang@huawei.com, ziy@nvidia.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20240628104926.34209-1-libang.li@antgroup.com> <4b38db15-0716-4ffb-a38b-bd6250eb93da@arm.com> <4d54880e-03f4-460a-94b9-e21b8ad13119@linux.alibaba.com> <516aa6b3-617c-4642-b12b-0c5f5b33d1c9@arm.com> <597ac51e-3f27-4606-8647-395bb4e60df4@redhat.com> From: Ryan Roberts In-Reply-To: <597ac51e-3f27-4606-8647-395bb4e60df4@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 01/07/2024 09:48, David Hildenbrand wrote: > On 01.07.24 10:40, Ryan Roberts wrote: >> On 01/07/2024 09:33, Baolin Wang wrote: >>> >>> >>> On 2024/7/1 15:55, Ryan Roberts wrote: >>>> On 28/06/2024 11:49, Bang Li wrote: >>>>> After the commit 7fb1b252afb5 ("mm: shmem: add mTHP support for >>>>> anonymous shmem"), we can configure different policies through >>>>> the multi-size THP sysfs interface for anonymous shmem. But >>>>> currently "THPeligible" indicates only whether the mapping is >>>>> eligible for allocating THP-pages as well as the THP is PMD >>>>> mappable or not for anonymous shmem, we need to support semantics >>>>> for mTHP with anonymous shmem similar to those for mTHP with >>>>> anonymous memory. >>>>> >>>>> Signed-off-by: Bang Li >>>>> --- >>>>>    fs/proc/task_mmu.c      | 10 +++++++--- >>>>>    include/linux/huge_mm.h | 11 +++++++++++ >>>>>    mm/shmem.c              |  9 +-------- >>>>>    3 files changed, 19 insertions(+), 11 deletions(-) >>>>> >>>>> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c >>>>> index 93fb2c61b154..09b5db356886 100644 >>>>> --- a/fs/proc/task_mmu.c >>>>> +++ b/fs/proc/task_mmu.c >>>>> @@ -870,6 +870,7 @@ static int show_smap(struct seq_file *m, void *v) >>>>>    { >>>>>        struct vm_area_struct *vma = v; >>>>>        struct mem_size_stats mss = {}; >>>>> +    bool thp_eligible; >>>>>          smap_gather_stats(vma, &mss, 0); >>>>>    @@ -882,9 +883,12 @@ static int show_smap(struct seq_file *m, void *v) >>>>>          __show_smap(m, &mss, false); >>>>>    -    seq_printf(m, "THPeligible:    %8u\n", >>>>> -           !!thp_vma_allowable_orders(vma, vma->vm_flags, >>>>> -               TVA_SMAPS | TVA_ENFORCE_SYSFS, THP_ORDERS_ALL)); >>>>> +    thp_eligible = !!thp_vma_allowable_orders(vma, vma->vm_flags, >>>>> +                        TVA_SMAPS | TVA_ENFORCE_SYSFS, THP_ORDERS_ALL); >>>>> +    if (vma_is_anon_shmem(vma)) >>>>> +        thp_eligible = >>>>> !!shmem_allowable_huge_orders(file_inode(vma->vm_file), >>>>> +                            vma, vma->vm_pgoff, thp_eligible); >>>> >>>> Afraid I haven't been following the shmem mTHP support work as much as I would >>>> have liked, but is there a reason why we need a separate function for shmem? >>> >>> Since shmem_allowable_huge_orders() only uses shmem specific logic to determine >>> if huge orders are allowable, there is no need to complicate the >>> thp_vma_allowable_orders() function by adding more shmem related logic, making >>> it more bloated. In my view, providing a dedicated helper >>> shmem_allowable_huge_orders(), specifically for shmem, simplifies the logic. >> >> My point was really that a single interface (thp_vma_allowable_orders) should be >> used to get this information. I have no strong opinon on how the implementation >> of that interface looks. What you suggest below seems perfectly reasonable to me. > > Right. thp_vma_allowable_orders() might require some care as discussed in other > context (cleanly separate dax and shmem handling/orders). But that would be > follow-up cleanups. Are you planning to do that, or do you want me to send a patch?