From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out0-201.mail.aliyun.com (out0-201.mail.aliyun.com [140.205.0.201]) (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 D91B1181CEC for ; Wed, 3 Jul 2024 16:02:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=140.205.0.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720022584; cv=none; b=Og8in3xV26g8S4rCXRhGXXJsOqI3Fknlm3G5f1xM2pD4TW5d9RUFa5lF0znDCVu8Dl8ikyPjlzwn1cBmUqVphdSbA8iwGAwOV+VysEX/xWazKfGG6f8ELxo10A6wVGCekSlClXsEL64mjz6kn3YaacS3aMmTMIJhcpA/oIcF4s4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720022584; c=relaxed/simple; bh=8pFiVaNxNvjH2yFvBrjip4x0kMlOb0M0FLvSnAVGtsU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=rbWR9bVRbKCAIq+FHKIaLc5XhxE6/Ec3xV/f39QKI1FGIMt2DIkfY2QVkHAFKbJkeJPW2PmAOzeGAvY+aisBvjl99qG1jC0xlknI2g5LlJ6SIpJHhlfrql73YdDiHtZL9FZh7/Uoc1FAM7QSd8Z8Z9A0vtn+E7F5FXMMoJVoVdo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=antgroup.com; spf=pass smtp.mailfrom=antgroup.com; dkim=pass (1024-bit key) header.d=antgroup.com header.i=@antgroup.com header.b=GTQiTFVP; arc=none smtp.client-ip=140.205.0.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=antgroup.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=antgroup.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=antgroup.com header.i=@antgroup.com header.b="GTQiTFVP" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=antgroup.com; s=default; t=1720022572; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=u8cIspOx+Kmuer/vpt0eeOp7L8p2EbLDnQLFewuL1rY=; b=GTQiTFVPhZ4VSMNQ0qux/qqWioUv/jUJaCLxUSeW2ljON4saggtZ5BLWkfE4ngS0JQT6Ao3B3Q/qTcObKHLMfkefn1IcNt55PcB3KkKoWckOCb63qCvptffDvjXUIugD8QBBAx41Cdnh1RbygwvBt2SdDER5MjOkMNw9RS+J/lM= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R181e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033040106183;MF=libang.li@antgroup.com;NM=1;PH=DS;RN=10;SR=0;TI=SMTPD_---.YGdjyw9_1720022569; Received: from 30.39.194.34(mailfrom:libang.li@antgroup.com fp:SMTPD_---.YGdjyw9_1720022569) by smtp.aliyun-inc.com; Thu, 04 Jul 2024 00:02:50 +0800 Message-ID: Date: Thu, 04 Jul 2024 00:02:48 +0800 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 v2] mm: thp: support "THPeligible" semantics for mTHP with anonymous shmem To: Ryan Roberts , ughd@google.com, akpm@linux-foundation.org Cc: david@redhat.com, wangkefeng.wang@huawei.com, baolin.wang@linux.alibaba.com, ioworker0@gmail.com, ziy@nvidia.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20240702023401.41553-1-libang.li@antgroup.com> <507da6d0-77c5-46ca-8351-53b405ecb131@arm.com> <8c018e06-74f1-46e9-bc32-b3870342cdc1@antgroup.com> <8d9e501a-0645-4b78-809a-7c9f49f2106d@arm.com> Content-Language: en-US From: "Bang Li" In-Reply-To: <8d9e501a-0645-4b78-809a-7c9f49f2106d@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2024/7/3 18:25, Ryan Roberts wrote: > On 03/07/2024 08:33, Bang Li wrote: >> Hi Ryan, >> >> Thanks for the review! >> >> On 2024/7/2 16:18, Ryan Roberts wrote: >>> On 02/07/2024 03:34, 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 >>>> --- >>>> Changes since v1 [1]: >>>>   - Put anonymous shmem mthp related logic into >>>>     thp_vma_allowable_orders() (per David) >>>> >>>> [1] >>>> https://lore.kernel.org/linux-mm/20240628104926.34209-1-libang.li@antgroup.com/ >>>> --- >>>>   include/linux/huge_mm.h | 11 +++++++++++ >>>>   mm/huge_memory.c        | 13 +++++++++---- >>>>   mm/shmem.c              |  9 +-------- >>>>   3 files changed, 21 insertions(+), 12 deletions(-) >>>> >>>> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h >>>> index 212cca384d7e..f87136f38aa1 100644 >>>> --- a/include/linux/huge_mm.h >>>> +++ b/include/linux/huge_mm.h >>>> @@ -267,6 +267,10 @@ unsigned long thp_vma_allowable_orders(struct >>>> vm_area_struct *vma, >>>>       return __thp_vma_allowable_orders(vma, vm_flags, tva_flags, orders); >>>>   } >>>>   +unsigned long shmem_allowable_huge_orders(struct inode *inode, >>>> +                struct vm_area_struct *vma, pgoff_t index, >>>> +                bool global_huge); >>>> + >>>>   struct thpsize { >>>>       struct kobject kobj; >>>>       struct list_head node; >>>> @@ -460,6 +464,13 @@ static inline unsigned long >>>> thp_vma_allowable_orders(struct vm_area_struct *vma, >>>>       return 0; >>>>   } >>>>   +static inline unsigned long shmem_allowable_huge_orders(struct inode *inode, >>>> +                struct vm_area_struct *vma, pgoff_t index, >>>> +                bool global_huge) >>>> +{ >>>> +    return 0; >>>> +} >>>> + >>>>   #define transparent_hugepage_flags 0UL >>>>     #define thp_get_unmapped_area    NULL >>>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >>>> index c7ce28f6b7f3..ea377bb4af91 100644 >>>> --- a/mm/huge_memory.c >>>> +++ b/mm/huge_memory.c >>>> @@ -151,10 +151,15 @@ unsigned long __thp_vma_allowable_orders(struct >>>> vm_area_struct *vma, >>>>        * Must be done before hugepage flags check since shmem has its >>>>        * own flags. >>>>        */ >>>> -    if (!in_pf && shmem_file(vma->vm_file)) >>>> -        return shmem_is_huge(file_inode(vma->vm_file), vma->vm_pgoff, >>>> -                     !enforce_sysfs, vma->vm_mm, vm_flags) >>>> -            ? orders : 0; >>>> +    if (!in_pf && shmem_file(vma->vm_file)) { >>>> +        bool global_huge = shmem_is_huge(file_inode(vma->vm_file), >>>> vma->vm_pgoff, >>>> +                            !enforce_sysfs, vma->vm_mm, vm_flags); >>>> + >>>> +        if (!vma_is_anon_shmem(vma)) >>>> +            return global_huge? orders : 0; >>> >>> nit: missing space before '?' >> >> Yes, thanks. >> >>> >>>> +        return shmem_allowable_huge_orders(file_inode(vma->vm_file), >>>> +                            vma, vma->vm_pgoff, global_huge); >>> >>> What's the rationale for splitting these functions into shmem_is_huge() and >>> shmem_allowable_huge_orders()? Why not just have a single >>> shmem_allowable_huge_orders() that tells you the answer? >>> >> >> Currently, shmem_is_huge() is used for all shmem implementations to determine >> whether the conditions for using THP are met. And shmem_allowable_huge_orders() >> is currently mainly used for anonymous shmem's mTHP to obtain all orders that >> meet the conditions. In my opinion, there is no problem in separating these two >> functions. In the future, when mTHP of other shmem types is also implemented, >> will shmem_is_huge() be unnecessary? > > Personally, I consider shmem_is_huge() to be superfluous; If you have one > function, shmem_allowable_huge_orders(), that gives you all the information you > need. If the inode only allows PMD-size, then only return that bit in the field. > IMHO removing shmem_is_huge() would make things more readable. Thank you very much for your opinion. I think there is no big problem in keeping the current interface status quo. In my opinion, when we implement mTHP for all shmems, it may be better to remove shmem_is_huge() and use shmem_allowable_huge_orders() uniformly. I believe that it won't be long before someone proposes a non-anonymous shared mTHP patchset. Anyway, thank you for your suggestion :). Thanks, Bang > > Thanks, > Ryan > >> >> Thanks, >> Bang >> >>>> +    } >>>>         if (!vma_is_anonymous(vma)) { >>>>           /* >>>> diff --git a/mm/shmem.c b/mm/shmem.c >>>> index d495c0701a83..aa85df9c662a 100644 >>>> --- a/mm/shmem.c >>>> +++ b/mm/shmem.c >>>> @@ -1622,7 +1622,7 @@ static gfp_t limit_gfp_mask(gfp_t huge_gfp, gfp_t >>>> limit_gfp) >>>>   } >>>>     #ifdef CONFIG_TRANSPARENT_HUGEPAGE >>>> -static unsigned long shmem_allowable_huge_orders(struct inode *inode, >>>> +unsigned long shmem_allowable_huge_orders(struct inode *inode, >>>>                   struct vm_area_struct *vma, pgoff_t index, >>>>                   bool global_huge) >>>>   { >>>> @@ -1707,13 +1707,6 @@ static unsigned long shmem_suitable_orders(struct >>>> inode *inode, struct vm_fault >>>>       return orders; >>>>   } >>>>   #else >>>> -static unsigned long shmem_allowable_huge_orders(struct inode *inode, >>>> -                struct vm_area_struct *vma, pgoff_t index, >>>> -                bool global_huge) >>>> -{ >>>> -    return 0; >>>> -} >>>> - >>>>   static unsigned long shmem_suitable_orders(struct inode *inode, struct >>>> vm_fault *vmf, >>>>                          struct address_space *mapping, pgoff_t index, >>>>                          unsigned long orders)