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[35.185.212.55]) by smtp.gmail.com with ESMTPSA id w4-20020a63b744000000b003fd4831e6fesm11324352pgt.70.2022.06.21.11.58.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Jun 2022 11:58:37 -0700 (PDT) Date: Tue, 21 Jun 2022 11:58:34 -0700 From: Zach O'Keefe To: Yang Shi Cc: vbabka@suse.cz, kirill.shutemov@linux.intel.com, willy@infradead.org, linmiaohe@huawei.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [v5 PATCH 4/7] mm: thp: kill transparent_hugepage_active() Message-ID: References: <20220616174840.1202070-1-shy828301@gmail.com> <20220616174840.1202070-5-shy828301@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220616174840.1202070-5-shy828301@gmail.com> ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1655837920; a=rsa-sha256; cv=none; b=3wHT75muJrhOwzKM0D3WVHWvFbTAzoRIxrzOXCJBHkEHricTc96Xlhjfkw1Cak+dIbVo5X eVhsbdy2O/N4Uccki3/ibWhYQF/3n8TgNXmXdAVHo83FqpFsa25nJ5mfZhfDkSFPR2soj7 73rGPtb6QpyJSmP1HPcG7DGyaINvNrk= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=lRmo2M0V; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf05.hostedemail.com: domain of zokeefe@google.com designates 209.85.210.182 as permitted sender) smtp.mailfrom=zokeefe@google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1655837920; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=42vsJg2fPvcjlY+3cTeVot4f6HOKgMA3yaicXV9Nn9g=; b=Kvojj3A6FR1+c8QCqqJhAwK/EW7Va30hKJqGX+5DK2gk3Nxqr91ZJL9a0jKaGgFBN46cgy YxcJUJekK+SKLgpXhbMhY0g93LuXMEEa1cPMdtpBLZ3Tbpu7q/IlR/I1K6yMGP4GGkSQJ2 i7RbpANnkjrUkXebxwpVp7jtVlJ++Ro= X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 1DA06100015 X-Stat-Signature: 69yetrpwwectcmnf7r6j7etf93bfiik1 X-Rspam-User: Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=lRmo2M0V; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf05.hostedemail.com: domain of zokeefe@google.com designates 209.85.210.182 as permitted sender) smtp.mailfrom=zokeefe@google.com X-HE-Tag: 1655837919-788966 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: On 16 Jun 10:48, 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(). > > This patch also fixed the wrong behavior for VM_NO_KHUGEPAGED vmas. > > Also move hugepage_vma_check() to huge_memory.c and huge_mm.h since it > is not only for khugepaged anymore. > > Reviewed-by: Zach O'Keefe > Signed-off-by: Yang Shi > --- > fs/proc/task_mmu.c | 2 +- > include/linux/huge_mm.h | 16 +++++++----- > include/linux/khugepaged.h | 2 -- > mm/huge_memory.c | 50 +++++++++++++++++++++++++++++++------- > mm/khugepaged.c | 48 +++--------------------------------- > 5 files changed, 56 insertions(+), 62 deletions(-) > > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c > index 37ccb5c9f4f8..39a40ec181e7 100644 > --- a/fs/proc/task_mmu.c > +++ b/fs/proc/task_mmu.c > @@ -863,7 +863,7 @@ 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 8a5a8bfce0f5..64487bcd0c7b 100644 > --- a/include/linux/huge_mm.h > +++ b/include/linux/huge_mm.h > @@ -202,7 +202,9 @@ 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 & \ > @@ -351,11 +353,6 @@ 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_suitable(struct vm_area_struct *vma, > unsigned long addr) > { > @@ -368,6 +365,13 @@ 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 31ca8a7f78f4..ea5fd4c398f7 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, > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index b530462c4493..a28c6100b491 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -69,21 +69,53 @@ 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) > { > - /* The addr is used to check if the vma size fits */ > - unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE; > + if (!transhuge_vma_enabled(vma, vm_flags)) > + return false; > + During testing my work on top this patch, I found a small bug here. Namely, transhuge_vma_enabled() will check vma->vm_mm->flags (to see if MMF_DISABLE_THP is set); however, for vDSO vmas, vma->vm_mm is NULL. Previously, transparent_hugepage_active() in smaps path would check transhuge_vma_suitable() before checking these flags, which would fail for vDSO vma since we'd take the !vma_is_anonymous() branch and find the vma (most likely) wasn't suitably aligned (by chance ?). Anyways, I think we need to check vma->vm_mm. > + if (vm_flags & VM_NO_KHUGEPAGED) > + return false; > + > + /* Don't run khugepaged against DAX vma */ > + if (vma_is_dax(vma)) > + return false; > > - if (!transhuge_vma_suitable(vma, addr)) > + /* Check alignment for file vma and size for both file and anon vma */ > + if (!transhuge_vma_suitable(vma, (vma->vm_end - HPAGE_PMD_SIZE))) > return false; > - 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; > } > > static bool get_huge_zero_page(void) > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 5baa394e34c8..3afd87f8c0b1 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -437,46 +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; > - > - /* Check alignment for file vma and size for both file and anon vma */ > - if (!transhuge_vma_suitable(vma, (vma->vm_end - HPAGE_PMD_SIZE))) > - 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; > @@ -513,7 +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); > } > } > @@ -958,7 +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; > /* > * Anon VMA expected, the address may be unmapped then > @@ -1448,7 +1408,7 @@ 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() */ > @@ -2143,7 +2103,7 @@ 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 >