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 43B4582C6C for ; Mon, 1 Jul 2024 08:40:37 +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=1719823241; cv=none; b=BSDBeHhLVHwrcemIfYeui+u48Sc//vDoQ1u/ubojpFwhRKBvDnMijYha/4kGEOrsai3YphaM0J2TnAvh8YamHmx9tn/i7NYzg7FbOWwOVw23wANnTpI6jDzGi+OWlty04We/XlEqE9E0Na3wjsvLFIgmnC/xbqiD1cU15+vxat8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719823241; c=relaxed/simple; bh=ZypCh53St70/iDwLmK0LimJkap2qCPTKgx83lJROPDc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=hMygYvCUdqAJqW7BpgzpBN4jcaNkM/4gp+bI6diWCGH8TPOhRTE7+JdtB5xD+Q5liwej0IgXlitmGzKSkjsaG4jveoQC5tMFLPDyYdUtpKWiVSS55otasg73VdTvcHyXNhaOG7qDXw+iFwpuuuE5LupgNehJg3opwVvrbSkDHkY= 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 57C9F339; Mon, 1 Jul 2024 01:41:02 -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 D38A83F766; Mon, 1 Jul 2024 01:40:35 -0700 (PDT) Message-ID: <516aa6b3-617c-4642-b12b-0c5f5b33d1c9@arm.com> Date: Mon, 1 Jul 2024 09:40:34 +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: Baolin Wang , Bang Li , hughd@google.com, akpm@linux-foundation.org Cc: david@redhat.com, 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> From: Ryan Roberts In-Reply-To: <4d54880e-03f4-460a-94b9-e21b8ad13119@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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. > > IIUC, I agree with David's suggestion that the shmem_allowable_huge_orders() > helper function could be used in thp_vma_allowable_orders() to support shmem > mTHP. Something like: I hadn't seen David's suggestion until after I sent my mail. But I think we are both suggesting the same thing. > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index c7ce28f6b7f3..9677fe6cf478 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -151,10 +151,13 @@ 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); > + > +               return shmem_allowable_huge_orders(file_inode(vma->vm_file), > +                                       vma, vma->vm_pgoff, global_huge); > +       } > >         if (!vma_is_anonymous(vma)) { >                 /* > >> Couldn't (shouldn't) thp_vma_allowable_orders() be taught to handle shmem too? >> >>> +    seq_printf(m, "THPeligible:    %8u\n", thp_eligible); >>>         if (arch_pkeys_enabled()) >>>           seq_printf(m, "ProtectionKey:  %8u\n", vma_pkey(vma)); >>> 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/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)