Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933314AbcK1OcH (ORCPT ); Mon, 28 Nov 2016 09:32:07 -0500 Received: from mail-wm0-f65.google.com ([74.125.82.65]:35547 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933085AbcK1Obf (ORCPT ); Mon, 28 Nov 2016 09:31:35 -0500 Date: Mon, 28 Nov 2016 15:31:32 +0100 From: Michal Hocko To: Naoya Horiguchi Cc: linux-mm@kvack.org, "Kirill A. Shutemov" , Hugh Dickins , Andrew Morton , Dave Hansen , Andrea Arcangeli , Mel Gorman , Vlastimil Babka , Pavel Emelyanov , Zi Yan , Balbir Singh , linux-kernel@vger.kernel.org, Naoya Horiguchi Subject: Re: [PATCH v2 05/12] mm: thp: add core routines for thp/pmd migration Message-ID: <20161128143132.GN14788@dhcp22.suse.cz> References: <1478561517-4317-1-git-send-email-n-horiguchi@ah.jp.nec.com> <1478561517-4317-6-git-send-email-n-horiguchi@ah.jp.nec.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1478561517-4317-6-git-send-email-n-horiguchi@ah.jp.nec.com> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 11719 Lines: 360 On Tue 08-11-16 08:31:50, Naoya Horiguchi wrote: > This patch prepares thp migration's core code. These code will be open when > unmap_and_move() stops unconditionally splitting thp and get_new_page() starts > to allocate destination thps. this description is underdocumented to say the least. Could you provide a high level documentation here please? > Signed-off-by: Naoya Horiguchi > --- > ChangeLog v1 -> v2: > - support pte-mapped thp, doubly-mapped thp > --- > arch/x86/include/asm/pgtable_64.h | 2 + > include/linux/swapops.h | 61 +++++++++++++++ > mm/huge_memory.c | 154 ++++++++++++++++++++++++++++++++++++++ > mm/migrate.c | 44 ++++++++++- > mm/pgtable-generic.c | 3 +- > 5 files changed, 262 insertions(+), 2 deletions(-) > > diff --git v4.9-rc2-mmotm-2016-10-27-18-27/arch/x86/include/asm/pgtable_64.h v4.9-rc2-mmotm-2016-10-27-18-27_patched/arch/x86/include/asm/pgtable_64.h > index 1cc82ec..3a1b48e 100644 > --- v4.9-rc2-mmotm-2016-10-27-18-27/arch/x86/include/asm/pgtable_64.h > +++ v4.9-rc2-mmotm-2016-10-27-18-27_patched/arch/x86/include/asm/pgtable_64.h > @@ -167,7 +167,9 @@ static inline int pgd_large(pgd_t pgd) { return 0; } > ((type) << (SWP_TYPE_FIRST_BIT)) \ > | ((offset) << SWP_OFFSET_FIRST_BIT) }) > #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val((pte)) }) > +#define __pmd_to_swp_entry(pte) ((swp_entry_t) { pmd_val((pmd)) }) > #define __swp_entry_to_pte(x) ((pte_t) { .pte = (x).val }) > +#define __swp_entry_to_pmd(x) ((pmd_t) { .pmd = (x).val }) > > extern int kern_addr_valid(unsigned long addr); > extern void cleanup_highmap(void); > diff --git v4.9-rc2-mmotm-2016-10-27-18-27/include/linux/swapops.h v4.9-rc2-mmotm-2016-10-27-18-27_patched/include/linux/swapops.h > index 5c3a5f3..b6b22a2 100644 > --- v4.9-rc2-mmotm-2016-10-27-18-27/include/linux/swapops.h > +++ v4.9-rc2-mmotm-2016-10-27-18-27_patched/include/linux/swapops.h > @@ -163,6 +163,67 @@ static inline int is_write_migration_entry(swp_entry_t entry) > > #endif > > +#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION > +extern void set_pmd_migration_entry(struct page *page, > + struct vm_area_struct *vma, unsigned long address); > + > +extern int remove_migration_pmd(struct page *new, pmd_t *pmd, > + struct vm_area_struct *vma, unsigned long addr, void *old); > + > +extern void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd); > + > +static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd) > +{ > + swp_entry_t arch_entry; > + > + arch_entry = __pmd_to_swp_entry(pmd); > + return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry)); > +} > + > +static inline pmd_t swp_entry_to_pmd(swp_entry_t entry) > +{ > + swp_entry_t arch_entry; > + > + arch_entry = __swp_entry(swp_type(entry), swp_offset(entry)); > + return __swp_entry_to_pmd(arch_entry); > +} > + > +static inline int is_pmd_migration_entry(pmd_t pmd) > +{ > + return !pmd_present(pmd) && is_migration_entry(pmd_to_swp_entry(pmd)); > +} > +#else > +static inline void set_pmd_migration_entry(struct page *page, > + struct vm_area_struct *vma, unsigned long address) > +{ > +} > + > +static inline int remove_migration_pmd(struct page *new, pmd_t *pmd, > + struct vm_area_struct *vma, unsigned long addr, void *old) > +{ > + return 0; > +} > + > +static inline void pmd_migration_entry_wait(struct mm_struct *m, pmd_t *p) { } > + > +static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd) > +{ > + return swp_entry(0, 0); > +} > + > +static inline pmd_t swp_entry_to_pmd(swp_entry_t entry) > +{ > + pmd_t pmd = {}; > + > + return pmd; > +} > + > +static inline int is_pmd_migration_entry(pmd_t pmd) > +{ > + return 0; > +} > +#endif > + > #ifdef CONFIG_MEMORY_FAILURE > > extern atomic_long_t num_poisoned_pages __read_mostly; > diff --git v4.9-rc2-mmotm-2016-10-27-18-27/mm/huge_memory.c v4.9-rc2-mmotm-2016-10-27-18-27_patched/mm/huge_memory.c > index 0509d17..b3022b3 100644 > --- v4.9-rc2-mmotm-2016-10-27-18-27/mm/huge_memory.c > +++ v4.9-rc2-mmotm-2016-10-27-18-27_patched/mm/huge_memory.c > @@ -2310,3 +2310,157 @@ static int __init split_huge_pages_debugfs(void) > } > late_initcall(split_huge_pages_debugfs); > #endif > + > +#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION > +void set_pmd_migration_entry(struct page *page, struct vm_area_struct *vma, > + unsigned long addr) > +{ > + struct mm_struct *mm = vma->vm_mm; > + pgd_t *pgd; > + pud_t *pud; > + pmd_t *pmd; > + pmd_t pmdval; > + swp_entry_t entry; > + spinlock_t *ptl; > + > + pgd = pgd_offset(mm, addr); > + if (!pgd_present(*pgd)) > + return; > + pud = pud_offset(pgd, addr); > + if (!pud_present(*pud)) > + return; > + pmd = pmd_offset(pud, addr); > + pmdval = *pmd; > + barrier(); > + if (!pmd_present(pmdval)) > + return; > + > + mmu_notifier_invalidate_range_start(mm, addr, addr + HPAGE_PMD_SIZE); > + if (pmd_trans_huge(pmdval)) { > + pmd_t pmdswp; > + > + ptl = pmd_lock(mm, pmd); > + if (!pmd_present(*pmd)) > + goto unlock_pmd; > + if (unlikely(!pmd_trans_huge(*pmd))) > + goto unlock_pmd; > + if (pmd_page(*pmd) != page) > + goto unlock_pmd; > + > + pmdval = pmdp_huge_get_and_clear(mm, addr, pmd); > + if (pmd_dirty(pmdval)) > + set_page_dirty(page); > + entry = make_migration_entry(page, pmd_write(pmdval)); > + pmdswp = swp_entry_to_pmd(entry); > + pmdswp = pmd_mkhuge(pmdswp); > + set_pmd_at(mm, addr, pmd, pmdswp); > + page_remove_rmap(page, true); > + put_page(page); > +unlock_pmd: > + spin_unlock(ptl); > + } else { /* pte-mapped thp */ > + pte_t *pte; > + pte_t pteval; > + struct page *tmp = compound_head(page); > + unsigned long address = addr & HPAGE_PMD_MASK; > + pte_t swp_pte; > + int i; > + > + pte = pte_offset_map(pmd, address); > + ptl = pte_lockptr(mm, pmd); > + spin_lock(ptl); > + for (i = 0; i < HPAGE_PMD_NR; i++, pte++, tmp++) { > + if (!(pte_present(*pte) && > + page_to_pfn(tmp) == pte_pfn(*pte))) > + continue; > + pteval = ptep_clear_flush(vma, address, pte); > + if (pte_dirty(pteval)) > + set_page_dirty(tmp); > + entry = make_migration_entry(tmp, pte_write(pteval)); > + swp_pte = swp_entry_to_pte(entry); > + set_pte_at(mm, address, pte, swp_pte); > + page_remove_rmap(tmp, false); > + put_page(tmp); > + } > + pte_unmap_unlock(pte, ptl); > + } > + mmu_notifier_invalidate_range_end(mm, addr, addr + HPAGE_PMD_SIZE); > + return; > +} > + > +int remove_migration_pmd(struct page *new, pmd_t *pmd, > + struct vm_area_struct *vma, unsigned long addr, void *old) > +{ > + struct mm_struct *mm = vma->vm_mm; > + spinlock_t *ptl; > + pmd_t pmde; > + swp_entry_t entry; > + > + pmde = *pmd; > + barrier(); > + > + if (!pmd_present(pmde)) { > + if (is_migration_entry(pmd_to_swp_entry(pmde))) { > + unsigned long mmun_start = addr & HPAGE_PMD_MASK; > + unsigned long mmun_end = mmun_start + HPAGE_PMD_SIZE; > + > + ptl = pmd_lock(mm, pmd); > + entry = pmd_to_swp_entry(*pmd); > + if (migration_entry_to_page(entry) != old) > + goto unlock_ptl; > + get_page(new); > + pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot)); > + if (is_write_migration_entry(entry)) > + pmde = maybe_pmd_mkwrite(pmde, vma); > + flush_cache_range(vma, mmun_start, mmun_end); > + page_add_anon_rmap(new, vma, mmun_start, true); > + pmdp_huge_clear_flush_notify(vma, mmun_start, pmd); > + set_pmd_at(mm, mmun_start, pmd, pmde); > + flush_tlb_range(vma, mmun_start, mmun_end); > + if (vma->vm_flags & VM_LOCKED) > + mlock_vma_page(new); > + update_mmu_cache_pmd(vma, addr, pmd); > +unlock_ptl: > + spin_unlock(ptl); > + } > + } else { /* pte-mapped thp */ > + pte_t *ptep; > + pte_t pte; > + int i; > + struct page *tmpnew = compound_head(new); > + struct page *tmpold = compound_head((struct page *)old); > + unsigned long address = addr & HPAGE_PMD_MASK; > + > + ptep = pte_offset_map(pmd, addr); > + ptl = pte_lockptr(mm, pmd); > + spin_lock(ptl); > + > + for (i = 0; i < HPAGE_PMD_NR; > + i++, ptep++, tmpnew++, tmpold++, address += PAGE_SIZE) { > + pte = *ptep; > + if (!is_swap_pte(pte)) > + continue; > + entry = pte_to_swp_entry(pte); > + if (!is_migration_entry(entry) || > + migration_entry_to_page(entry) != tmpold) > + continue; > + get_page(tmpnew); > + pte = pte_mkold(mk_pte(tmpnew, > + READ_ONCE(vma->vm_page_prot))); > + if (pte_swp_soft_dirty(*ptep)) > + pte = pte_mksoft_dirty(pte); > + if (is_write_migration_entry(entry)) > + pte = maybe_mkwrite(pte, vma); > + flush_dcache_page(tmpnew); > + set_pte_at(mm, address, ptep, pte); > + if (PageAnon(new)) > + page_add_anon_rmap(tmpnew, vma, address, false); > + else > + page_add_file_rmap(tmpnew, false); > + update_mmu_cache(vma, address, ptep); > + } > + pte_unmap_unlock(ptep, ptl); > + } > + return SWAP_AGAIN; > +} > +#endif > diff --git v4.9-rc2-mmotm-2016-10-27-18-27/mm/migrate.c v4.9-rc2-mmotm-2016-10-27-18-27_patched/mm/migrate.c > index 66ce6b4..54f2eb6 100644 > --- v4.9-rc2-mmotm-2016-10-27-18-27/mm/migrate.c > +++ v4.9-rc2-mmotm-2016-10-27-18-27_patched/mm/migrate.c > @@ -198,6 +198,8 @@ static int remove_migration_pte(struct page *new, struct vm_area_struct *vma, > { > struct mm_struct *mm = vma->vm_mm; > swp_entry_t entry; > + pgd_t *pgd; > + pud_t *pud; > pmd_t *pmd; > pte_t *ptep, pte; > spinlock_t *ptl; > @@ -208,10 +210,29 @@ static int remove_migration_pte(struct page *new, struct vm_area_struct *vma, > goto out; > ptl = huge_pte_lockptr(hstate_vma(vma), mm, ptep); > } else { > - pmd = mm_find_pmd(mm, addr); > + pmd_t pmde; > + > + pgd = pgd_offset(mm, addr); > + if (!pgd_present(*pgd)) > + goto out; > + pud = pud_offset(pgd, addr); > + if (!pud_present(*pud)) > + goto out; > + pmd = pmd_offset(pud, addr); > if (!pmd) > goto out; > > + if (PageTransCompound(new)) { > + remove_migration_pmd(new, pmd, vma, addr, old); > + goto out; > + } > + > + pmde = *pmd; > + barrier(); > + > + if (!pmd_present(pmde) || pmd_trans_huge(pmde)) > + goto out; > + > ptep = pte_offset_map(pmd, addr); > > /* > @@ -344,6 +365,27 @@ void migration_entry_wait_huge(struct vm_area_struct *vma, > __migration_entry_wait(mm, pte, ptl); > } > > +#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION > +void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd) > +{ > + spinlock_t *ptl; > + struct page *page; > + > + ptl = pmd_lock(mm, pmd); > + if (!is_pmd_migration_entry(*pmd)) > + goto unlock; > + page = migration_entry_to_page(pmd_to_swp_entry(*pmd)); > + if (!get_page_unless_zero(page)) > + goto unlock; > + spin_unlock(ptl); > + wait_on_page_locked(page); > + put_page(page); > + return; > +unlock: > + spin_unlock(ptl); > +} > +#endif > + > #ifdef CONFIG_BLOCK > /* Returns true if all buffers are successfully locked */ > static bool buffer_migrate_lock_buffers(struct buffer_head *head, > diff --git v4.9-rc2-mmotm-2016-10-27-18-27/mm/pgtable-generic.c v4.9-rc2-mmotm-2016-10-27-18-27_patched/mm/pgtable-generic.c > index 71c5f91..6012343 100644 > --- v4.9-rc2-mmotm-2016-10-27-18-27/mm/pgtable-generic.c > +++ v4.9-rc2-mmotm-2016-10-27-18-27_patched/mm/pgtable-generic.c > @@ -118,7 +118,8 @@ pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address, > { > pmd_t pmd; > VM_BUG_ON(address & ~HPAGE_PMD_MASK); > - VM_BUG_ON(!pmd_trans_huge(*pmdp) && !pmd_devmap(*pmdp)); > + VM_BUG_ON(pmd_present(*pmdp) && !pmd_trans_huge(*pmdp) && > + !pmd_devmap(*pmdp)); > pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp); > flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE); > return pmd; > -- > 2.7.0 -- Michal Hocko SUSE Labs