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s=arc-20220608; d=hostedemail.com; t=1719823842; a=rsa-sha256; cv=none; b=jI/JFyhi/Wl9HQc4JFisunIOaipd1wyxWLUdXSy31FGmJXrh6PuwtH6kspWfnGzho8N7aW 5QaCDFHFOoC+XgtUDP4h7ZWCvVk5Ys+NucHRYZ7s7iou/jJVI8S+Lg4h3RWrreVk8Ih9x9 Z+JIZx7J57gvdHWFRCauH7C7EnFspAk= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=none; spf=pass (imf06.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com; dmarc=pass (policy=none) header.from=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 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 X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 555EF180014 X-Stat-Signature: kps1cx55iwfweq76rgihkcshkrkcuqoe X-HE-Tag: 1719823863-756386 X-HE-Meta: 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 iRrK7WF/ 1YfZnJYWuBRhcFBGWmqIL03OeTeqhVEWUf1jTwbflvwmnodK+ZQufQ+25+uAa4cNBbdlxaocqeCrPTPCVn4MN+ZnsWMXZljKqeKDbxulXxjDppOLnRHjN6qteTnZovmirScpzu/yiuIVojIMJ9d4HVCI/sZTijiv8c5/jx81XE+JhvC1sigPZ3+Prtg/IV6cS3Z8bH+tGMRdLDWHx+1jnkSHP9EU8fTlj1n79 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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?