From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DE544C43334 for ; Tue, 14 Jun 2022 19:16:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344564AbiFNTQy (ORCPT ); Tue, 14 Jun 2022 15:16:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57130 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230343AbiFNTQv (ORCPT ); Tue, 14 Jun 2022 15:16:51 -0400 Received: from mail-pj1-x1033.google.com (mail-pj1-x1033.google.com [IPv6:2607:f8b0:4864:20::1033]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1BACE11C0F for ; Tue, 14 Jun 2022 12:16:50 -0700 (PDT) Received: by mail-pj1-x1033.google.com with SMTP id a10so9277421pju.3 for ; Tue, 14 Jun 2022 12:16:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=VbSkMKIaORvzbd33+XhP133adIiO0N/caPCUotYrdxI=; b=qRaBWoSqRpZ1j93EX6kX4XWHreLVThvMHs8UaXH4bdwkmg9WzXzUD+QzcfjGGgisNi ineATZgMUCe+ztfnCYxkW8CECv9SuUBw+x32ku5AcVQKMtJ9zQjciqWKZtW26OxGzLeD TEsaGgBgmwBZvWA9doN5cP4uXE38znFSFp6Ek0zRsyTJPX3f6JuZlwcH8qf8+uRekH6R cyLLtzQfIXrnYFiNq4sxtJSTHJw6YZHPjHXKqqFIezHJ/Ld+bmKYpxCi0D9RyelaSlUB EvQESj0cQxxBh7kJmeY5LT8DL20Gm6pWnCf0MhxVZTDJ1B7TmEIeF98Y4hme/7NJu2yl VKxA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=VbSkMKIaORvzbd33+XhP133adIiO0N/caPCUotYrdxI=; b=z+lTSQ9j3WURxCzztCJ6fRNbIq6sj34GIo5oJjVRc2Z06cA7c1eHdznnxtbd0u+f0D CEZoZEVIyHfqxRJnbKf9M4tESKOoKPwxgSRiOicusyc1FJBBI/lQc4I7DoGWNbP781Y6 RuVrjukVtoo/AiaBmQs8byrf8ZmqrbWy6846V1RZddGEtLewOpq5OIGLTHBCKCkf3k80 yOPiLMDh+E2xuGH6D/h5JDZBYIE3ZDrj43J0JGMu2Ahy/Ts52Rm2PIKrneu6+7k4KTut PfV9JW1CEOJ5K2JPeKYUdbSLcjuA7TFzt16ZJVniRSwIJLs/F2a+R1sUa/ceFelgx8vp ly7Q== X-Gm-Message-State: AJIora+tul049tOiR45ji+3A/3+q33U8VpAjKaXKgI/AG5h53mDig1wa yWbs7fmfPdjKRqq9hm9aanmlj4cwdv2rTTW2B/s= X-Google-Smtp-Source: AGRyM1ug+PPQpVWuIfgSvJB1ZhxNuTHN8ArxO7wGVhr1q4odRIFokOFRdEg/gy13M+v3CVIjoWO8AI+y0MwOy0MxbWU= X-Received: by 2002:a17:902:c40a:b0:163:d38e:3049 with SMTP id k10-20020a170902c40a00b00163d38e3049mr5817297plk.87.1655234209436; Tue, 14 Jun 2022 12:16:49 -0700 (PDT) MIME-Version: 1.0 References: <20220606214414.736109-1-shy828301@gmail.com> <20220606214414.736109-6-shy828301@gmail.com> In-Reply-To: From: Yang Shi Date: Tue, 14 Jun 2022 12:16:36 -0700 Message-ID: Subject: Re: [v3 PATCH 5/7] mm: thp: kill transparent_hugepage_active() To: "Zach O'Keefe" Cc: Vlastimil Babka , "Kirill A. Shutemov" , Matthew Wilcox , Andrew Morton , Linux MM , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 13, 2022 at 8:06 AM Zach O'Keefe wrote: > > On 10 Jun 10:02, Yang Shi wrote: > > On Thu, Jun 9, 2022 at 6:03 PM Zach O'Keefe wrote: > > > > > > On Mon, Jun 6, 2022 at 2:44 PM Yang Shi wrote: > > > > > > > > The transparent_hugepage_active() was introduced to show THP eligibility > > > > bit in smaps in proc, smaps is the only user. But it actually does the > > > > similar check as hugepage_vma_check() which is used by khugepaged. We > > > > definitely don't have to maintain two similar checks, so kill > > > > transparent_hugepage_active(). > > > > > > I never realized smaps was the only user! Great! > > > > > > > Also move hugepage_vma_check() to huge_memory.c and huge_mm.h since it > > > > is not only for khugepaged anymore. > > > > > > > > Signed-off-by: Yang Shi > > > > --- > > > > fs/proc/task_mmu.c | 2 +- > > > > include/linux/huge_mm.h | 16 +++++++----- > > > > include/linux/khugepaged.h | 4 +-- > > > > mm/huge_memory.c | 50 ++++++++++++++++++++++++++++++++----- > > > > mm/khugepaged.c | 51 +++----------------------------------- > > > > 5 files changed, 60 insertions(+), 63 deletions(-) > > > > > > > > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c > > > > index 2dd8c8a66924..fd79566e204c 100644 > > > > --- a/fs/proc/task_mmu.c > > > > +++ b/fs/proc/task_mmu.c > > > > @@ -860,7 +860,7 @@ static int show_smap(struct seq_file *m, void *v) > > > > __show_smap(m, &mss, false); > > > > > > > > seq_printf(m, "THPeligible: %d\n", > > > > - transparent_hugepage_active(vma)); > > > > + hugepage_vma_check(vma, vma->vm_flags, true)); > > > > > > > > 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 79d5919beb83..f561c3e16def 100644 > > > > --- a/include/linux/huge_mm.h > > > > +++ b/include/linux/huge_mm.h > > > > @@ -209,7 +209,9 @@ static inline bool file_thp_enabled(struct vm_area_struct *vma) > > > > !inode_is_open_for_write(inode) && S_ISREG(inode->i_mode); > > > > } > > > > > > > > -bool transparent_hugepage_active(struct vm_area_struct *vma); > > > > +bool hugepage_vma_check(struct vm_area_struct *vma, > > > > + unsigned long vm_flags, > > > > + bool smaps); > > > > > > > > #define transparent_hugepage_use_zero_page() \ > > > > (transparent_hugepage_flags & \ > > > > @@ -358,11 +360,6 @@ static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma) > > > > return false; > > > > } > > > > > > > > -static inline bool transparent_hugepage_active(struct vm_area_struct *vma) > > > > -{ > > > > - return false; > > > > -} > > > > - > > > > static inline bool transhuge_vma_size_ok(struct vm_area_struct *vma) > > > > { > > > > return false; > > > > @@ -380,6 +377,13 @@ static inline bool transhuge_vma_enabled(struct vm_area_struct *vma, > > > > return false; > > > > } > > > > > > > > +static inline bool hugepage_vma_check(struct vm_area_struct *vma, > > > > + unsigned long vm_flags, > > > > + bool smaps) > > > > +{ > > > > + return false; > > > > +} > > > > + > > > > static inline void prep_transhuge_page(struct page *page) {} > > > > > > > > #define transparent_hugepage_flags 0UL > > > > diff --git a/include/linux/khugepaged.h b/include/linux/khugepaged.h > > > > index 392d34c3c59a..8a6452e089ca 100644 > > > > --- a/include/linux/khugepaged.h > > > > +++ b/include/linux/khugepaged.h > > > > @@ -10,8 +10,6 @@ extern struct attribute_group khugepaged_attr_group; > > > > extern int khugepaged_init(void); > > > > extern void khugepaged_destroy(void); > > > > extern int start_stop_khugepaged(void); > > > > -extern bool hugepage_vma_check(struct vm_area_struct *vma, > > > > - unsigned long vm_flags); > > > > extern void __khugepaged_enter(struct mm_struct *mm); > > > > extern void __khugepaged_exit(struct mm_struct *mm); > > > > extern void khugepaged_enter_vma(struct vm_area_struct *vma, > > > > @@ -57,7 +55,7 @@ static inline void khugepaged_enter(struct vm_area_struct *vma, > > > > { > > > > if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) && > > > > khugepaged_enabled()) { > > > > - if (hugepage_vma_check(vma, vm_flags)) > > > > + if (hugepage_vma_check(vma, vm_flags, false)) > > > > __khugepaged_enter(vma->vm_mm); > > > > } > > > > } > > > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > > > > index 36ada544e494..bc8370856e85 100644 > > > > --- a/mm/huge_memory.c > > > > +++ b/mm/huge_memory.c > > > > @@ -69,18 +69,56 @@ static atomic_t huge_zero_refcount; > > > > struct page *huge_zero_page __read_mostly; > > > > unsigned long huge_zero_pfn __read_mostly = ~0UL; > > > > > > > > -bool transparent_hugepage_active(struct vm_area_struct *vma) > > > > +bool hugepage_vma_check(struct vm_area_struct *vma, > > > > + unsigned long vm_flags, > > > > + bool smaps) > > > > { > > > > + if (!transhuge_vma_enabled(vma, vm_flags)) > > > > + return false; > > > > + > > > > + if (vm_flags & VM_NO_KHUGEPAGED) > > > > + return false; > > > > + > > > > + /* Don't run khugepaged against DAX vma */ > > > > + if (vma_is_dax(vma)) > > > > + return false; > > > > + > > > > + if (vma->vm_file && !IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - > > > > + vma->vm_pgoff, HPAGE_PMD_NR)) > > > > + return false; > > > > + > > > > if (!transhuge_vma_size_ok(vma)) > > > > return false; > > I know we just introduced transhuge_vma_size_ok(), but is there a way to > consolidate the above two checks into a single transhuge_vma_suitable(), the > same way it used to be done in transparent_hugepage_active()? I.e. > > transhuge_vma_suitable(vma, vma->vm_end - HPAGE_PMD_SIZE). > > Which checks if the vma can hold an aligned hugepage, as well as centralizes > the (what I think to be) complicated file mapping check. Good point. Thanks for the suggestion. Actually transhuge_vma_size_ok() is just called by hugepage_vma_check(). And hugepage_vma_check() does check the alignment for file vma too, so I think they could be consolidated into one function as you suggested. And this should help keep the THPeligible bit the same throughout the series. > > > > > - if (vma_is_anonymous(vma)) > > > > - return __transparent_hugepage_enabled(vma); > > > > - if (vma_is_shmem(vma)) > > > > + > > > > + /* Enabled via shmem mount options or sysfs settings. */ > > > > + if (shmem_file(vma->vm_file)) > > > > return shmem_huge_enabled(vma); > > > > - if (transhuge_vma_enabled(vma, vma->vm_flags) && file_thp_enabled(vma)) > > > > + > > > > + if (!khugepaged_enabled()) > > > > + return false; > > > > + > > > > + /* THP settings require madvise. */ > > > > + if (!(vm_flags & VM_HUGEPAGE) && !khugepaged_always()) > > > > + return false; > > > > + > > > > + /* Only regular file is valid */ > > > > + if (file_thp_enabled(vma)) > > > > return true; > > > > > > > > - return false; > > > > + if (!vma_is_anonymous(vma)) > > > > + return false; > > > > + > > > > + if (vma_is_temporary_stack(vma)) > > > > + return false; > > > > + > > > > + /* > > > > + * THPeligible bit of smaps should show 1 for proper VMAs even > > > > + * though anon_vma is not initialized yet. > > > > + */ > > > > + if (!vma->anon_vma) > > > > + return smaps; > > > > + > > > > + return true; > > > > } > > > > > > There are a few cases where the return value for smaps will be > > > different from before. I presume this won't be an issue, and that any > > > difference resulting from this change is actually a positive > > > difference, given it more accurately reflects the thp eligibility of > > > the vma? For example, a VM_NO_KHUGEPAGED-marked vma might now show 0 > > > where it otherwise showed 1. > > > > Yes, returning 1 for VM_NO_KHUGEPAGED vmas is wrong. Actually TBH I > > suspect very few people actually use this bit. Anyway I will elaborate > > this in the commit log. > > > > > > > > > static bool get_huge_zero_page(void) > > > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > > > > index ca1754d3a827..aa0769e3b0d9 100644 > > > > --- a/mm/khugepaged.c > > > > +++ b/mm/khugepaged.c > > > > @@ -437,49 +437,6 @@ static inline int khugepaged_test_exit(struct mm_struct *mm) > > > > return atomic_read(&mm->mm_users) == 0; > > > > } > > > > > > > > -bool hugepage_vma_check(struct vm_area_struct *vma, > > > > - unsigned long vm_flags) > > > > -{ > > > > - if (!transhuge_vma_enabled(vma, vm_flags)) > > > > - return false; > > > > - > > > > - if (vm_flags & VM_NO_KHUGEPAGED) > > > > - return false; > > > > - > > > > - /* Don't run khugepaged against DAX vma */ > > > > - if (vma_is_dax(vma)) > > > > - return false; > > > > - > > > > - if (vma->vm_file && !IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - > > > > - vma->vm_pgoff, HPAGE_PMD_NR)) > > > > - return false; > > > > - > > > > - if (!transhuge_vma_size_ok(vma)) > > > > - return false; > > > > - > > > > - /* Enabled via shmem mount options or sysfs settings. */ > > > > - if (shmem_file(vma->vm_file)) > > > > - return shmem_huge_enabled(vma); > > > > - > > > > - if (!khugepaged_enabled()) > > > > - return false; > > > > - > > > > - /* THP settings require madvise. */ > > > > - if (!(vm_flags & VM_HUGEPAGE) && !khugepaged_always()) > > > > - return false; > > > > - > > > > - /* Only regular file is valid */ > > > > - if (file_thp_enabled(vma)) > > > > - return true; > > > > - > > > > - if (!vma->anon_vma || !vma_is_anonymous(vma)) > > > > - return false; > > > > - if (vma_is_temporary_stack(vma)) > > > > - return false; > > > > - > > > > - return true; > > > > -} > > > > - > > > > void __khugepaged_enter(struct mm_struct *mm) > > > > { > > > > struct mm_slot *mm_slot; > > > > @@ -516,7 +473,7 @@ void khugepaged_enter_vma(struct vm_area_struct *vma, > > > > { > > > > if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) && > > > > khugepaged_enabled()) { > > > > - if (hugepage_vma_check(vma, vm_flags)) > > > > + if (hugepage_vma_check(vma, vm_flags, false)) > > > > __khugepaged_enter(vma->vm_mm); > > > > } > > > > } > > > > @@ -961,7 +918,7 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, > > > > > > > > if (!transhuge_vma_suitable(vma, address)) > > > > return SCAN_ADDRESS_RANGE; > > > > - if (!hugepage_vma_check(vma, vma->vm_flags)) > > > > + if (!hugepage_vma_check(vma, vma->vm_flags, false)) > > > > return SCAN_VMA_CHECK; > > > > return 0; > > > > } > > > > @@ -1442,7 +1399,7 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) > > > > * the valid THP. Add extra VM_HUGEPAGE so hugepage_vma_check() > > > > * will not fail the vma for missing VM_HUGEPAGE > > > > */ > > > > - if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE)) > > > > + if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE, false)) > > > > return; > > > > > > > > /* Keep pmd pgtable for uffd-wp; see comment in retract_page_tables() */ > > > > @@ -2132,7 +2089,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, > > > > progress++; > > > > break; > > > > } > > > > - if (!hugepage_vma_check(vma, vma->vm_flags)) { > > > > + if (!hugepage_vma_check(vma, vma->vm_flags, false)) { > > > > skip: > > > > progress++; > > > > continue; > > > > -- > > > > 2.26.3 > > > > > > > >