Re: [PATCH v4 4/4] mm: introduce MADV_PAGEOUT
From: Minchan Kim <minchan@kernel.org>
Date: 2019-07-12 05:18:39
Also in:
linux-mm, lkml
Subsystem:
memory management, memory mapping - madvise (memory advice), the rest · Maintainers:
Andrew Morton, Liam R. Howlett, Lorenzo Stoakes, David Hildenbrand, Linus Torvalds
Hi Johannes, On Thu, Jul 11, 2019 at 02:42:23PM -0400, Johannes Weiner wrote:
On Thu, Jul 11, 2019 at 10:25:28AM +0900, Minchan Kim wrote:quoted
@@ -480,6 +482,198 @@ 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; + 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); + 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); + } + + 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); + 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 (isolate_lru_page(page)) + continue; + + 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); + 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; +}I know you have briefly talked about code sharing already. While I agree that sharing with MADV_FREE is maybe a stretch, I applied these patches and compared the pageout and the cold page table functions, and they are line for line the same EXCEPT for 2-3 lines at the very end, where one reclaims and the other deactivates. It would be good to share here, it shouldn't be hard or result in fragile code.
Fair enough if we leave MADV_FREE.
Something like int madvise_cold_or_pageout_range(..., bool pageout)?
How about this?
From 41592f23e876ec21e49dc3c76dc89538e2bb16be Mon Sep 17 00:00:00 2001
From: Minchan Kim <minchan@kernel.org> Date: Fri, 12 Jul 2019 14:05:36 +0900 Subject: [PATCH] mm: factor out common parts between MADV_COLD and MADV_PAGEOUT There are many common parts between MADV_COLD and MADV_PAGEOUT. This patch factor them out to save code duplication. Signed-off-by: Minchan Kim <minchan@kernel.org> --- mm/madvise.c | 201 +++++++++++++-------------------------------------- 1 file changed, 52 insertions(+), 149 deletions(-)
diff --git a/mm/madvise.c b/mm/madvise.c
index bc2f0138982e..3d3d14517cc8 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c@@ -30,6 +30,11 @@ #include "internal.h" +struct madvise_walk_private { + struct mmu_gather *tlb; + bool pageout; +}; + /* * Any behaviour which results in changes to the vma->vm_flags needs to * take mmap_sem for writing. Others, which simply traverse vmas, need
@@ -310,16 +315,23 @@ static long madvise_willneed(struct vm_area_struct *vma, return 0; } -static int madvise_cold_pte_range(pmd_t *pmd, unsigned long addr, - unsigned long end, struct mm_walk *walk) +static int madvise_cold_or_pageout_pte_range(pmd_t *pmd, + unsigned long addr, unsigned long end, + struct mm_walk *walk) { - struct mmu_gather *tlb = walk->private; + struct madvise_walk_private *private = walk->private; + struct mmu_gather *tlb = private->tlb; + bool pageout = private->pageout; struct mm_struct *mm = tlb->mm; struct vm_area_struct *vma = walk->vma; pte_t *orig_pte, *pte, ptent; spinlock_t *ptl; - struct page *page; unsigned long next; + struct page *page = NULL; + LIST_HEAD(page_list); + + if (fatal_signal_pending(current)) + return -EINTR; next = pmd_addr_end(addr, end); if (pmd_trans_huge(*pmd)) {
@@ -358,6 +370,12 @@ static int madvise_cold_pte_range(pmd_t *pmd, unsigned long addr, return 0; } + if (pageout) { + if (isolate_lru_page(page)) + goto huge_unlock; + list_add(&page->lru, &page_list); + } + if (pmd_young(orig_pmd)) { pmdp_invalidate(vma, addr, pmd); orig_pmd = pmd_mkold(orig_pmd);
@@ -366,10 +384,14 @@ static int madvise_cold_pte_range(pmd_t *pmd, unsigned long addr, tlb_remove_pmd_tlb_entry(tlb, pmd, addr); } + ClearPageReferenced(page); test_and_clear_page_young(page); - deactivate_page(page); huge_unlock: spin_unlock(ptl); + if (pageout) + reclaim_pages(&page_list); + else + deactivate_page(page); return 0; }
@@ -423,6 +445,12 @@ static int madvise_cold_pte_range(pmd_t *pmd, unsigned long addr, VM_BUG_ON_PAGE(PageTransCompound(page), page); + if (pageout) { + if (isolate_lru_page(page)) + continue; + list_add(&page->lru, &page_list); + } + if (pte_young(ptent)) { ptent = ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm);
@@ -437,12 +465,16 @@ static int madvise_cold_pte_range(pmd_t *pmd, unsigned long addr, * As a side effect, it makes confuse idle-page tracking * because they will miss recent referenced history. */ + ClearPageReferenced(page); test_and_clear_page_young(page); - deactivate_page(page); + if (!pageout) + deactivate_page(page); } arch_enter_lazy_mmu_mode(); pte_unmap_unlock(orig_pte, ptl); + if (pageout) + reclaim_pages(&page_list); cond_resched(); return 0;
@@ -452,10 +484,15 @@ static void madvise_cold_page_range(struct mmu_gather *tlb, struct vm_area_struct *vma, unsigned long addr, unsigned long end) { + struct madvise_walk_private walk_private = { + .tlb = tlb, + .pageout = false, + }; + struct mm_walk cold_walk = { - .pmd_entry = madvise_cold_pte_range, + .pmd_entry = madvise_cold_or_pageout_pte_range, .mm = vma->vm_mm, - .private = tlb, + .private = &walk_private, }; tlb_start_vma(tlb, vma);
@@ -482,153 +519,19 @@ 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; - 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); - 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); - } - - 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); - 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 (isolate_lru_page(page)) - continue; - - 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); - 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 madvise_walk_private walk_private = { + .pageout = true, + .tlb = tlb, + }; + struct mm_walk pageout_walk = { - .pmd_entry = madvise_pageout_pte_range, + .pmd_entry = madvise_cold_or_pageout_pte_range, .mm = vma->vm_mm, - .private = tlb, + .private = &walk_private, }; tlb_start_vma(tlb, vma);
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2.22.0.410.gd8fdbe21b5-goog