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Shutemov" , Minchan Kim Subject: [PATCH v3 5/5] mm: factor out pmd young/dirty bit handling and THP split Date: Thu, 27 Jun 2019 20:54:05 +0900 Message-Id: <20190627115405.255259-6-minchan@kernel.org> X-Mailer: git-send-email 2.22.0.410.gd8fdbe21b5-goog In-Reply-To: <20190627115405.255259-1-minchan@kernel.org> References: <20190627115405.255259-1-minchan@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Now, there are common part among MADV_COLD|PAGEOUT|FREE to reset access/dirty bit resetting or split the THP page to handle part of subpages in the THP page. This patch factor out the common part. Signed-off-by: Minchan Kim --- include/linux/huge_mm.h | 3 - mm/huge_memory.c | 74 ------------- mm/madvise.c | 234 +++++++++++++++++++++++----------------- 3 files changed, 135 insertions(+), 176 deletions(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 7cd5c150c21d..2667e1aa3ce5 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -29,9 +29,6 @@ extern struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, unsigned long addr, pmd_t *pmd, unsigned int flags); -extern bool madvise_free_huge_pmd(struct mmu_gather *tlb, - struct vm_area_struct *vma, - pmd_t *pmd, unsigned long addr, unsigned long next); extern int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr); diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 93f531b63a45..e4b9a06788f3 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1671,80 +1671,6 @@ vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd) return 0; } -/* - * Return true if we do MADV_FREE successfully on entire pmd page. - * Otherwise, return false. - */ -bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, - pmd_t *pmd, unsigned long addr, unsigned long next) -{ - spinlock_t *ptl; - pmd_t orig_pmd; - struct page *page; - struct mm_struct *mm = tlb->mm; - bool ret = false; - - tlb_change_page_size(tlb, HPAGE_PMD_SIZE); - - ptl = pmd_trans_huge_lock(pmd, vma); - if (!ptl) - goto out_unlocked; - - orig_pmd = *pmd; - if (is_huge_zero_pmd(orig_pmd)) - goto out; - - if (unlikely(!pmd_present(orig_pmd))) { - VM_BUG_ON(thp_migration_supported() && - !is_pmd_migration_entry(orig_pmd)); - goto out; - } - - page = pmd_page(orig_pmd); - /* - * If other processes are mapping this page, we couldn't discard - * the page unless they all do MADV_FREE so let's skip the page. - */ - if (page_mapcount(page) != 1) - goto out; - - if (!trylock_page(page)) - goto out; - - /* - * If user want to discard part-pages of THP, split it so MADV_FREE - * will deactivate only them. - */ - if (next - addr != HPAGE_PMD_SIZE) { - get_page(page); - spin_unlock(ptl); - split_huge_page(page); - unlock_page(page); - put_page(page); - goto out_unlocked; - } - - if (PageDirty(page)) - ClearPageDirty(page); - unlock_page(page); - - if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { - pmdp_invalidate(vma, addr, pmd); - orig_pmd = pmd_mkold(orig_pmd); - orig_pmd = pmd_mkclean(orig_pmd); - - set_pmd_at(mm, addr, pmd, orig_pmd); - tlb_remove_pmd_tlb_entry(tlb, pmd, addr); - } - - mark_page_lazyfree(page); - ret = true; -out: - spin_unlock(ptl); -out_unlocked: - return ret; -} - static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) { pgtable_t pgtable; diff --git a/mm/madvise.c b/mm/madvise.c index ee210473f639..13b06dc8d402 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -310,6 +310,91 @@ static long madvise_willneed(struct vm_area_struct *vma, return 0; } +enum madv_pmdp_reset_t { + MADV_PMDP_RESET, /* pmd was reset successfully */ + MADV_PMDP_SPLIT, /* pmd was split */ + MADV_PMDP_ERROR, +}; + +static enum madv_pmdp_reset_t madvise_pmdp_reset_or_split(struct mm_walk *walk, + pmd_t *pmd, spinlock_t *ptl, + unsigned long addr, unsigned long end, + bool young, bool dirty) +{ + pmd_t orig_pmd; + unsigned long next; + struct page *page; + struct mmu_gather *tlb = walk->private; + struct mm_struct *mm = walk->mm; + struct vm_area_struct *vma = walk->vma; + bool reset_young = false; + bool reset_dirty = false; + enum madv_pmdp_reset_t ret = MADV_PMDP_ERROR; + + orig_pmd = *pmd; + if (is_huge_zero_pmd(orig_pmd)) + return ret; + + if (unlikely(!pmd_present(orig_pmd))) { + VM_BUG_ON(thp_migration_supported() && + !is_pmd_migration_entry(orig_pmd)); + return ret; + } + + next = pmd_addr_end(addr, end); + page = pmd_page(orig_pmd); + if (next - addr != HPAGE_PMD_SIZE) { + /* + * THP collapsing is not cheap so only split the page is + * private to the this process. + */ + if (page_mapcount(page) != 1) + return ret; + get_page(page); + spin_unlock(ptl); + lock_page(page); + if (!split_huge_page(page)) + ret = MADV_PMDP_SPLIT; + unlock_page(page); + put_page(page); + return ret; + } + + if (young && pmd_young(orig_pmd)) + reset_young = true; + if (dirty && pmd_dirty(orig_pmd)) + reset_dirty = true; + + /* + * Other process could rely on the PG_dirty for data consistency, + * not pte_dirty so we could reset PG_dirty only when we are owner + * of the page. + */ + if (reset_dirty) { + if (page_mapcount(page) != 1) + goto out; + if (!trylock_page(page)) + goto out; + if (PageDirty(page)) + ClearPageDirty(page); + unlock_page(page); + } + + ret = MADV_PMDP_RESET; + if (reset_young || reset_dirty) { + tlb_change_page_size(tlb, HPAGE_PMD_SIZE); + pmdp_invalidate(vma, addr, pmd); + if (reset_young) + orig_pmd = pmd_mkold(orig_pmd); + if (reset_dirty) + orig_pmd = pmd_mkclean(orig_pmd); + set_pmd_at(mm, addr, pmd, orig_pmd); + tlb_remove_pmd_tlb_entry(tlb, pmd, addr); + } +out: + return ret; +} + static int madvise_cold_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, struct mm_walk *walk) { @@ -319,64 +404,31 @@ static int madvise_cold_pte_range(pmd_t *pmd, unsigned long addr, pte_t *orig_pte, *pte, ptent; spinlock_t *ptl; struct page *page; - unsigned long next; - next = pmd_addr_end(addr, end); if (pmd_trans_huge(*pmd)) { - pmd_t orig_pmd; - - tlb_change_page_size(tlb, HPAGE_PMD_SIZE); ptl = pmd_trans_huge_lock(pmd, vma); if (!ptl) return 0; - orig_pmd = *pmd; - if (is_huge_zero_pmd(orig_pmd)) - goto huge_unlock; - - if (unlikely(!pmd_present(orig_pmd))) { - VM_BUG_ON(thp_migration_supported() && - !is_pmd_migration_entry(orig_pmd)); - goto huge_unlock; - } - - page = pmd_page(orig_pmd); - if (next - addr != HPAGE_PMD_SIZE) { - int err; - - if (page_mapcount(page) != 1) - goto huge_unlock; - - get_page(page); + switch (madvise_pmdp_reset_or_split(walk, pmd, ptl, addr, end, + true, false)) { + case MADV_PMDP_RESET: spin_unlock(ptl); - lock_page(page); - err = split_huge_page(page); - unlock_page(page); - put_page(page); - if (!err) - goto regular_page; - return 0; - } - - if (pmd_young(orig_pmd)) { - pmdp_invalidate(vma, addr, pmd); - orig_pmd = pmd_mkold(orig_pmd); - - set_pmd_at(mm, addr, pmd, orig_pmd); - tlb_remove_pmd_tlb_entry(tlb, pmd, addr); + page = pmd_page(*pmd); + test_and_clear_page_young(page); + deactivate_page(page); + goto next; + case MADV_PMDP_ERROR: + spin_unlock(ptl); + goto next; + case MADV_PMDP_SPLIT: + ; /* go through */ } - - test_and_clear_page_young(page); - deactivate_page(page); -huge_unlock: - spin_unlock(ptl); - return 0; } if (pmd_trans_unstable(pmd)) return 0; -regular_page: tlb_change_page_size(tlb, PAGE_SIZE); orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); flush_tlb_batched_pending(mm); @@ -443,6 +495,7 @@ static int madvise_cold_pte_range(pmd_t *pmd, unsigned long addr, arch_enter_lazy_mmu_mode(); pte_unmap_unlock(orig_pte, ptl); +next: cond_resched(); return 0; @@ -493,70 +546,38 @@ static int madvise_pageout_pte_range(pmd_t *pmd, unsigned long addr, LIST_HEAD(page_list); struct page *page; int isolated = 0; - unsigned long next; if (fatal_signal_pending(current)) return -EINTR; - next = pmd_addr_end(addr, end); if (pmd_trans_huge(*pmd)) { - pmd_t orig_pmd; - - tlb_change_page_size(tlb, HPAGE_PMD_SIZE); ptl = pmd_trans_huge_lock(pmd, vma); if (!ptl) return 0; - orig_pmd = *pmd; - if (is_huge_zero_pmd(orig_pmd)) - goto huge_unlock; - - if (unlikely(!pmd_present(orig_pmd))) { - VM_BUG_ON(thp_migration_supported() && - !is_pmd_migration_entry(orig_pmd)); - goto huge_unlock; - } - - page = pmd_page(orig_pmd); - if (next - addr != HPAGE_PMD_SIZE) { - int err; - - if (page_mapcount(page) != 1) - goto huge_unlock; - get_page(page); + switch (madvise_pmdp_reset_or_split(walk, pmd, ptl, addr, end, + true, false)) { + case MADV_PMDP_RESET: + page = pmd_page(*pmd); spin_unlock(ptl); - lock_page(page); - err = split_huge_page(page); - unlock_page(page); - put_page(page); - if (!err) - goto regular_page; - return 0; - } - - if (isolate_lru_page(page)) - goto huge_unlock; - - if (pmd_young(orig_pmd)) { - pmdp_invalidate(vma, addr, pmd); - orig_pmd = pmd_mkold(orig_pmd); - - set_pmd_at(mm, addr, pmd, orig_pmd); - tlb_remove_tlb_entry(tlb, pmd, addr); + if (isolate_lru_page(page)) + return 0; + ClearPageReferenced(page); + test_and_clear_page_young(page); + list_add(&page->lru, &page_list); + reclaim_pages(&page_list); + goto next; + case MADV_PMDP_ERROR: + spin_unlock(ptl); + goto next; + case MADV_PMDP_SPLIT: + ; /* go through */ } - - ClearPageReferenced(page); - test_and_clear_page_young(page); - list_add(&page->lru, &page_list); -huge_unlock: - spin_unlock(ptl); - reclaim_pages(&page_list); - return 0; } if (pmd_trans_unstable(pmd)) return 0; -regular_page: + tlb_change_page_size(tlb, PAGE_SIZE); orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); flush_tlb_batched_pending(mm); @@ -631,6 +652,7 @@ static int madvise_pageout_pte_range(pmd_t *pmd, unsigned long addr, arch_leave_lazy_mmu_mode(); pte_unmap_unlock(orig_pte, ptl); reclaim_pages(&page_list); +next: cond_resched(); return 0; @@ -700,12 +722,26 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr, pte_t *orig_pte, *pte, ptent; struct page *page; int nr_swap = 0; - unsigned long next; - next = pmd_addr_end(addr, end); - if (pmd_trans_huge(*pmd)) - if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next)) + if (pmd_trans_huge(*pmd)) { + ptl = pmd_trans_huge_lock(pmd, vma); + if (!ptl) + return 0; + + switch (madvise_pmdp_reset_or_split(walk, pmd, ptl, addr, end, + true, true)) { + case MADV_PMDP_RESET: + page = pmd_page(*pmd); + spin_unlock(ptl); + mark_page_lazyfree(page); goto next; + case MADV_PMDP_ERROR: + spin_unlock(ptl); + goto next; + case MADV_PMDP_SPLIT: + ; /* go through */ + } + } if (pmd_trans_unstable(pmd)) return 0; @@ -817,8 +853,8 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr, } arch_leave_lazy_mmu_mode(); pte_unmap_unlock(orig_pte, ptl); - cond_resched(); next: + cond_resched(); return 0; } -- 2.22.0.410.gd8fdbe21b5-goog