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 49D47176FD2 for ; Wed, 11 Sep 2024 12:22:26 +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=1726057347; cv=none; b=M/3k4PWLeEr2iJLAn8LtJ0i85bFb4/Dxkm0hu6wBIQqvWQe17KiC0bU8caMOL0MAJEY9WhqmJI9ddLGjFz1UXhFEzk1kMKDCDbckMDsjfixH/1T0c8GReS5ywjmBPZ9oO97BtywjGSOac4I8aeMBi7iWPhneDea0YfjFkWMVZow= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726057347; c=relaxed/simple; bh=v42Sj9D6OaSFuhsPueUxpnxKAyovlkCpVn2GHtI5AkU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=M8QVgjTdL2xxmpeBiTRuPEtYywtCaoSk3RysBYDDxewIm5mTo+2gCNfSMcUMqXCIZvrqJgnNlb+ijgnO317yyh45M53oD2nALMZ9CAaU2aSdIhVyoQS1yp9r97qxVOiqnqRzVmItSVSoMQbdAenFfbF1fKkIQr3BzKWLgVykmXw= 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 3122F1007; Wed, 11 Sep 2024 05:22:55 -0700 (PDT) Received: from [10.162.40.31] (e116581.arm.com [10.162.40.31]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7ABBB3F66E; Wed, 11 Sep 2024 05:22:16 -0700 (PDT) Message-ID: Date: Wed, 11 Sep 2024 17:52:13 +0530 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 v3 1/2] mm: Abstract THP allocation To: Kefeng Wang , akpm@linux-foundation.org, david@redhat.com, willy@infradead.org, kirill.shutemov@linux.intel.com Cc: ryan.roberts@arm.com, anshuman.khandual@arm.com, catalin.marinas@arm.com, cl@gentwo.org, vbabka@suse.cz, mhocko@suse.com, apopple@nvidia.com, dave.hansen@linux.intel.com, will@kernel.org, baohua@kernel.org, jack@suse.cz, mark.rutland@arm.com, hughd@google.com, aneesh.kumar@kernel.org, yang@os.amperecomputing.com, peterx@redhat.com, ioworker0@gmail.com, jglisse@google.com, ziy@nvidia.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20240911065600.1002644-1-dev.jain@arm.com> <20240911065600.1002644-2-dev.jain@arm.com> <170988b0-db8a-4612-a70c-b20ea2d4c020@huawei.com> Content-Language: en-US From: Dev Jain In-Reply-To: <170988b0-db8a-4612-a70c-b20ea2d4c020@huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 9/11/24 16:22, Kefeng Wang wrote: > > > On 2024/9/11 14:55, Dev Jain wrote: >> In preparation for the second patch, abstract away the THP allocation >> logic present in the create_huge_pmd() path, which corresponds to the >> faulting case when no page is present. >> >> There should be no functional change as a result of applying >> this patch. >> >> Signed-off-by: Dev Jain >> --- >>   mm/huge_memory.c | 110 +++++++++++++++++++++++++++++------------------ >>   1 file changed, 67 insertions(+), 43 deletions(-) >> >> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >> index 67c86a5d64a6..b96a1ff2bf40 100644 >> --- a/mm/huge_memory.c >> +++ b/mm/huge_memory.c >> @@ -943,47 +943,88 @@ unsigned long thp_get_unmapped_area(struct file >> *filp, unsigned long addr, >>   } >>   EXPORT_SYMBOL_GPL(thp_get_unmapped_area); >>   -static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, >> -            struct page *page, gfp_t gfp) >> +static struct folio *pmd_thp_fault_alloc(gfp_t gfp, struct >> vm_area_struct *vma, >> +                     unsigned long haddr, unsigned long addr) >>   { >> -    struct vm_area_struct *vma = vmf->vma; >> -    struct folio *folio = page_folio(page); >> -    pgtable_t pgtable; >> -    unsigned long haddr = vmf->address & HPAGE_PMD_MASK; >> -    vm_fault_t ret = 0; >> +    const int order = HPAGE_PMD_ORDER; > > Maybe move vma_thp_gfp_mask() into this function too. That's better, thanks. > >> +    struct folio *folio = vma_alloc_folio(gfp, order, vma, haddr, >> true); >>   -    VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); >> +    if (unlikely(!folio)) { >> +        count_vm_event(THP_FAULT_FALLBACK); >> +        count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK); >> +        goto out; >> +    } >>   +    VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); >>       if (mem_cgroup_charge(folio, vma->vm_mm, gfp)) { >>           folio_put(folio); >>           count_vm_event(THP_FAULT_FALLBACK); >>           count_vm_event(THP_FAULT_FALLBACK_CHARGE); >> -        count_mthp_stat(HPAGE_PMD_ORDER, >> MTHP_STAT_ANON_FAULT_FALLBACK); >> -        count_mthp_stat(HPAGE_PMD_ORDER, >> MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE); >> -        return VM_FAULT_FALLBACK; >> +        count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK); >> +        count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE); >> +        goto out; > > We need to return NULL here as folio not set to null, My bad for assuming that folio_put() also sets folio to NULL. I read through the code path for that and I guess it does not. Thanks. > >>       } >>       folio_throttle_swaprate(folio, gfp); >>   -    pgtable = pte_alloc_one(vma->vm_mm); >> -    if (unlikely(!pgtable)) { >> -        ret = VM_FAULT_OOM; >> -        goto release; >> -    } >> - >> -    folio_zero_user(folio, vmf->address); >> +    folio_zero_user(folio, addr); >>       /* >>        * The memory barrier inside __folio_mark_uptodate makes sure that >>        * folio_zero_user writes become visible before the set_pmd_at() >>        * write. >>        */ >>       __folio_mark_uptodate(folio); >> +out: >> +    return folio; >> +} >> +