From 23757dccf53d39ef82bdc1ddef7f229726248cc6 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Wed, 25 Sep 2019 16:49:15 -0700 Subject: [PATCH 0795/2944] mm: introduce MADV_PAGEOUT commit 1a4e58cce84ee88129d5d49c064bd2852b481357 upstream When a process expects no accesses to a certain memory range for a long time, it could hint kernel that the pages can be reclaimed instantly but data should be preserved for future use. This could reduce workingset eviction so it ends up increasing performance. This patch introduces the new MADV_PAGEOUT hint to madvise(2) syscall. MADV_PAGEOUT can be used by a process to mark a memory range as not expected to be used for a long time so that kernel reclaims *any LRU* pages instantly. The hint can help kernel in deciding which pages to evict proactively. A note: It doesn't apply SWAP_CLUSTER_MAX LRU page isolation limit intentionally because it's automatically bounded by PMD size. If PMD size(e.g., 256) makes some trouble, we could fix it later by limit it to SWAP_CLUSTER_MAX[1]. - man-page material MADV_PAGEOUT (since Linux x.x) Do not expect access in the near future so pages in the specified regions could be reclaimed instantly regardless of memory pressure. Thus, access in the range after successful operation could cause major page fault but never lose the up-to-date contents unlike MADV_DONTNEED. Pages belonging to a shared mapping are only processed if a write access is allowed for the calling process. MADV_PAGEOUT cannot be applied to locked pages, Huge TLB pages, or VM_PFNMAP pages. [1] https://lore.kernel.org/lkml/20190710194719.GS29695@dhcp22.suse.cz/ [minchan@kernel.org: clear PG_active on MADV_PAGEOUT] Link: http://lkml.kernel.org/r/20190802200643.GA181880@google.com [akpm@linux-foundation.org: resolve conflicts with hmm.git] Link: http://lkml.kernel.org/r/20190726023435.214162-5-minchan@kernel.org Signed-off-by: Minchan Kim Reported-by: kbuild test robot Acked-by: Michal Hocko Cc: James E.J. Bottomley Cc: Richard Henderson Cc: Ralf Baechle Cc: Chris Zankel Cc: Daniel Colascione Cc: Dave Hansen Cc: Hillf Danton Cc: Joel Fernandes (Google) Cc: Johannes Weiner Cc: Kirill A. Shutemov Cc: Oleksandr Natalenko Cc: Shakeel Butt Cc: Sonny Rao Cc: Suren Baghdasaryan Cc: Tim Murray Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Reviewed-by: Yang Shi Signed-off-by: Xunlei Pang --- arch/alpha/include/uapi/asm/mman.h | 1 + arch/mips/include/uapi/asm/mman.h | 1 + arch/parisc/include/uapi/asm/mman.h | 1 + arch/xtensa/include/uapi/asm/mman.h | 1 + include/linux/swap.h | 1 + include/uapi/asm-generic/mman-common.h | 1 + mm/madvise.c | 195 +++++++++++++++++++++++++++++++++ mm/vmscan.c | 56 ++++++++++ 8 files changed, 257 insertions(+) diff --git a/arch/alpha/include/uapi/asm/mman.h b/arch/alpha/include/uapi/asm/mman.h index f33b8af..128d2f2 100644 --- a/arch/alpha/include/uapi/asm/mman.h +++ b/arch/alpha/include/uapi/asm/mman.h @@ -71,6 +71,7 @@ #define MADV_KEEPONFORK 19 /* Undo MADV_WIPEONFORK */ #define MADV_COLD 20 /* deactivate these pages */ +#define MADV_PAGEOUT 21 /* reclaim these pages */ /* compatibility flags */ #define MAP_FILE 0 diff --git a/arch/mips/include/uapi/asm/mman.h b/arch/mips/include/uapi/asm/mman.h index db47689..6bdb40c 100644 --- a/arch/mips/include/uapi/asm/mman.h +++ b/arch/mips/include/uapi/asm/mman.h @@ -98,6 +98,7 @@ #define MADV_KEEPONFORK 19 /* Undo MADV_WIPEONFORK */ #define MADV_COLD 20 /* deactivate these pages */ +#define MADV_PAGEOUT 21 /* reclaim these pages */ /* compatibility flags */ #define MAP_FILE 0 diff --git a/arch/parisc/include/uapi/asm/mman.h b/arch/parisc/include/uapi/asm/mman.h index 64fc4af..bf0d98f 100644 --- a/arch/parisc/include/uapi/asm/mman.h +++ b/arch/parisc/include/uapi/asm/mman.h @@ -51,6 +51,7 @@ #define MADV_DOFORK 11 /* do inherit across fork */ #define MADV_COLD 20 /* deactivate these pages */ +#define MADV_PAGEOUT 21 /* reclaim these pages */ #define MADV_MERGEABLE 65 /* KSM may merge identical pages */ #define MADV_UNMERGEABLE 66 /* KSM may not merge identical pages */ diff --git a/arch/xtensa/include/uapi/asm/mman.h b/arch/xtensa/include/uapi/asm/mman.h index 00719bf..01e53db 100644 --- a/arch/xtensa/include/uapi/asm/mman.h +++ b/arch/xtensa/include/uapi/asm/mman.h @@ -110,6 +110,7 @@ #define MADV_KEEPONFORK 19 /* Undo MADV_WIPEONFORK */ #define MADV_COLD 20 /* deactivate these pages */ +#define MADV_PAGEOUT 21 /* reclaim these pages */ /* compatibility flags */ #define MAP_FILE 0 diff --git a/include/linux/swap.h b/include/linux/swap.h index 88a4884..4ec6168 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -369,6 +369,7 @@ extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem, extern int remove_mapping(struct address_space *mapping, struct page *page); extern unsigned long vm_total_pages; +extern unsigned long reclaim_pages(struct list_head *page_list); #ifdef CONFIG_NUMA extern int node_reclaim_mode; extern int sysctl_min_unmapped_ratio; diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h index 1d2107f..d889962 100644 --- a/include/uapi/asm-generic/mman-common.h +++ b/include/uapi/asm-generic/mman-common.h @@ -67,6 +67,7 @@ #define MADV_KEEPONFORK 19 /* Undo MADV_WIPEONFORK */ #define MADV_COLD 20 /* deactivate these pages */ +#define MADV_PAGEOUT 21 /* reclaim these pages */ /* compatibility flags */ #define MAP_FILE 0 diff --git a/mm/madvise.c b/mm/madvise.c index 4f7d24e..788a131 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -42,6 +42,7 @@ static int madvise_need_mmap_write(int behavior) case MADV_WILLNEED: case MADV_DONTNEED: case MADV_COLD: + case MADV_PAGEOUT: case MADV_FREE: return 0; default: @@ -481,6 +482,197 @@ static long madvise_cold(struct vm_area_struct *vma, return 0; } +static int madvise_pageout_pte_range(pmd_t *pmd, unsigned long addr, + unsigned long end, struct mm_walk *walk) +{ + struct mmu_gather *tlb = walk->private; + struct mm_struct *mm = tlb->mm; + struct vm_area_struct *vma = walk->vma; + pte_t *orig_pte, *pte, ptent; + spinlock_t *ptl; + LIST_HEAD(page_list); + struct page *page; + + if (fatal_signal_pending(current)) + return -EINTR; + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + if (pmd_trans_huge(*pmd)) { + pmd_t orig_pmd; + unsigned long next = pmd_addr_end(addr, end); + + tlb_remove_check_page_size_change(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); + 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_tlb_entry(tlb, pmd, addr); + } + + ClearPageReferenced(page); + test_and_clear_page_young(page); + + if (!isolate_lru_page(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: +#endif + tlb_remove_check_page_size_change(tlb, PAGE_SIZE); + orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); + flush_tlb_batched_pending(mm); + arch_enter_lazy_mmu_mode(); + for (; addr < end; pte++, addr += PAGE_SIZE) { + ptent = *pte; + if (!pte_present(ptent)) + continue; + + page = vm_normal_page(vma, addr, ptent); + if (!page) + continue; + + /* + * creating a THP page is expensive so split it only if we + * are sure it's worth. Split it if we are only owner. + */ + if (PageTransCompound(page)) { + if (page_mapcount(page) != 1) + break; + get_page(page); + if (!trylock_page(page)) { + put_page(page); + break; + } + pte_unmap_unlock(orig_pte, ptl); + if (split_huge_page(page)) { + unlock_page(page); + put_page(page); + pte_offset_map_lock(mm, pmd, addr, &ptl); + break; + } + unlock_page(page); + put_page(page); + pte = pte_offset_map_lock(mm, pmd, addr, &ptl); + pte--; + addr -= PAGE_SIZE; + continue; + } + + VM_BUG_ON_PAGE(PageTransCompound(page), page); + + if (pte_young(ptent)) { + ptent = ptep_get_and_clear_full(mm, addr, pte, + tlb->fullmm); + ptent = pte_mkold(ptent); + set_pte_at(mm, addr, pte, ptent); + tlb_remove_tlb_entry(tlb, pte, addr); + } + ClearPageReferenced(page); + test_and_clear_page_young(page); + + if (!isolate_lru_page(page)) + list_add(&page->lru, &page_list); + } + + arch_leave_lazy_mmu_mode(); + pte_unmap_unlock(orig_pte, ptl); + reclaim_pages(&page_list); + cond_resched(); + + return 0; +} + +static void madvise_pageout_page_range(struct mmu_gather *tlb, + struct vm_area_struct *vma, + unsigned long addr, unsigned long end) +{ + struct mm_walk pageout_walk = { + .pmd_entry = madvise_pageout_pte_range, + .mm = vma->vm_mm, + .private = tlb, + }; + + tlb_start_vma(tlb, vma); + walk_page_range(addr, end, &pageout_walk); + tlb_end_vma(tlb, vma); +} + +static inline bool can_do_pageout(struct vm_area_struct *vma) +{ + if (vma_is_anonymous(vma)) + return true; + if (!vma->vm_file) + return false; + /* + * paging out pagecache only for non-anonymous mappings that correspond + * to the files the calling process could (if tried) open for writing; + * otherwise we'd be including shared non-exclusive mappings, which + * opens a side channel. + */ + return inode_owner_or_capable(file_inode(vma->vm_file)) || + inode_permission(file_inode(vma->vm_file), MAY_WRITE) == 0; +} + +static long madvise_pageout(struct vm_area_struct *vma, + struct vm_area_struct **prev, + unsigned long start_addr, unsigned long end_addr) +{ + struct mm_struct *mm = vma->vm_mm; + struct mmu_gather tlb; + + *prev = vma; + if (!can_madv_lru_vma(vma)) + return -EINVAL; + + if (!can_do_pageout(vma)) + return 0; + + lru_add_drain(); + tlb_gather_mmu(&tlb, mm, start_addr, end_addr); + madvise_pageout_page_range(&tlb, vma, start_addr, end_addr); + tlb_finish_mmu(&tlb, start_addr, end_addr); + + return 0; +} + static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, struct mm_walk *walk) @@ -869,6 +1061,8 @@ static int madvise_inject_error(int behavior, return madvise_willneed(vma, prev, start, end); case MADV_COLD: return madvise_cold(vma, prev, start, end); + case MADV_PAGEOUT: + return madvise_pageout(vma, prev, start, end); case MADV_FREE: case MADV_DONTNEED: return madvise_dontneed_free(vma, prev, start, end, behavior); @@ -891,6 +1085,7 @@ static int madvise_inject_error(int behavior, case MADV_DONTNEED: case MADV_FREE: case MADV_COLD: + case MADV_PAGEOUT: #ifdef CONFIG_KSM case MADV_MERGEABLE: case MADV_UNMERGEABLE: diff --git a/mm/vmscan.c b/mm/vmscan.c index 3313d48..f771b65 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2253,6 +2253,62 @@ static void shrink_active_list(unsigned long nr_to_scan, nr_deactivate, nr_rotated, sc->priority, file); } +unsigned long reclaim_pages(struct list_head *page_list) +{ + int nid = -1; + unsigned long nr_reclaimed = 0; + LIST_HEAD(node_page_list); + struct reclaim_stat dummy_stat; + struct page *page; + struct scan_control sc = { + .gfp_mask = GFP_KERNEL, + .priority = DEF_PRIORITY, + .may_writepage = 1, + .may_unmap = 1, + .may_swap = 1, + }; + + while (!list_empty(page_list)) { + page = lru_to_page(page_list); + if (nid == -1) { + nid = page_to_nid(page); + INIT_LIST_HEAD(&node_page_list); + } + + if (nid == page_to_nid(page)) { + ClearPageActive(page); + list_move(&page->lru, &node_page_list); + continue; + } + + nr_reclaimed += shrink_page_list(&node_page_list, + NODE_DATA(nid), + &sc, 0, + &dummy_stat, false); + while (!list_empty(&node_page_list)) { + page = lru_to_page(&node_page_list); + list_del(&page->lru); + putback_lru_page(page); + } + + nid = -1; + } + + if (!list_empty(&node_page_list)) { + nr_reclaimed += shrink_page_list(&node_page_list, + NODE_DATA(nid), + &sc, 0, + &dummy_stat, false); + while (!list_empty(&node_page_list)) { + page = lru_to_page(&node_page_list); + list_del(&page->lru); + putback_lru_page(page); + } + } + + return nr_reclaimed; +} + /* * The inactive anon list should be small enough that the VM never has * to do too much work. -- 1.8.3.1