diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 7a3941492856..fee10d744ebd 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -298,6 +298,6 @@ static inline int page_mkclean(struct page *page) #define SWAP_AGAIN 1 #define SWAP_FAIL 2 #define SWAP_MLOCK 3 -#define SWAP_LZFREE 4 +#define SWAP_DIRTY 4 #endif /* _LINUX_RMAP_H */ diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 7309a716b7fc..08501a607b00 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1572,6 +1572,8 @@ bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 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); diff --git a/mm/madvise.c b/mm/madvise.c index cf3021b05b32..d3a6712c3e14 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -413,6 +413,7 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr, set_pte_at(mm, addr, pte, ptent); tlb_remove_tlb_entry(tlb, pte, addr); } + mark_page_lazyfree(page); } out: if (nr_swap) { diff --git a/mm/rmap.c b/mm/rmap.c index b4084d09dbe8..519b7eb723d1 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1288,11 +1288,6 @@ void page_remove_rmap(struct page *page, bool compound) */ } -struct rmap_private { - enum ttu_flags flags; - int lazyfreed; -}; - /* * @arg: enum ttu_flags will be passed to this argument */ @@ -1308,8 +1303,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, pte_t pteval; struct page *subpage; int ret = SWAP_AGAIN; - struct rmap_private *rp = arg; - enum ttu_flags flags = rp->flags; + enum ttu_flags flags = (enum ttu_flags)arg; /* munlock has nothing to gain from examining un-locked vmas */ if ((flags & TTU_MUNLOCK) && !(vma->vm_flags & VM_LOCKED)) @@ -1427,11 +1421,21 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, VM_BUG_ON_PAGE(!PageSwapCache(page) && PageSwapBacked(page), page); - if (!PageDirty(page)) { - /* It's a freeable page by MADV_FREE */ - dec_mm_counter(mm, MM_ANONPAGES); - rp->lazyfreed++; - goto discard; + /* MADV_FREE page check */ + if (!PageSwapBacked(page)) { + if (!PageDirty(page)) { + dec_mm_counter(mm, MM_ANONPAGES); + goto discard; + } + + /* + * If the page was redirtied, it cannot be + * discarded. Remap the page to page table. + */ + set_pte_at(mm, address, pvmw.pte, pteval); + ret = SWAP_DIRTY; + page_vma_mapped_walk_done(&pvmw); + break; } if (swap_duplicate(entry) < 0) { @@ -1499,18 +1503,15 @@ static int page_mapcount_is_zero(struct page *page) * SWAP_AGAIN - we missed a mapping, try again later * SWAP_FAIL - the page is unswappable * SWAP_MLOCK - page is mlocked. + * SWAP_DIRTY - page is dirty MADV_FREE page */ int try_to_unmap(struct page *page, enum ttu_flags flags) { int ret; - struct rmap_private rp = { - .flags = flags, - .lazyfreed = 0, - }; struct rmap_walk_control rwc = { .rmap_one = try_to_unmap_one, - .arg = &rp, + .arg = (void *)flags, .done = page_mapcount_is_zero, .anon_lock = page_lock_anon_vma_read, }; @@ -1531,11 +1532,8 @@ int try_to_unmap(struct page *page, enum ttu_flags flags) else ret = rmap_walk(page, &rwc); - if (ret != SWAP_MLOCK && !page_mapcount(page)) { + if (ret != SWAP_MLOCK && !page_mapcount(page)) ret = SWAP_SUCCESS; - if (rp.lazyfreed && !PageDirty(page)) - ret = SWAP_LZFREE; - } return ret; } @@ -1562,14 +1560,10 @@ static int page_not_mapped(struct page *page) int try_to_munlock(struct page *page) { int ret; - struct rmap_private rp = { - .flags = TTU_MUNLOCK, - .lazyfreed = 0, - }; struct rmap_walk_control rwc = { .rmap_one = try_to_unmap_one, - .arg = &rp, + .arg = (void *)TTU_MUNLOCK, .done = page_not_mapped, .anon_lock = page_lock_anon_vma_read, diff --git a/mm/vmscan.c b/mm/vmscan.c index e5c00f2b98ab..ec4555369e17 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -906,7 +906,8 @@ static void page_check_dirty_writeback(struct page *page, * Anonymous pages are not handled by flushers and must be written * from reclaim context. Do not stall reclaim based on them */ - if (!page_is_file_cache(page)) { + if (!page_is_file_cache(page) || + (PageAnon(page) && !PageSwapBacked(page))) { *dirty = false; *writeback = false; return; @@ -987,7 +988,8 @@ static unsigned long shrink_page_list(struct list_head *page_list, goto keep_locked; /* Double the slab pressure for mapped and swapcache pages */ - if (page_mapped(page) || PageSwapCache(page)) + if ((page_mapped(page) || PageSwapCache(page)) && + !(PageAnon(page) && !PageSwapBacked(page))) sc->nr_scanned++; may_enter_fs = (sc->gfp_mask & __GFP_FS) || @@ -1113,8 +1115,10 @@ static unsigned long shrink_page_list(struct list_head *page_list, /* * Anonymous process memory has backing store? * Try to allocate it some swap space here. + * Lazyfree page could be freed directly */ - if (PageAnon(page) && !PageSwapCache(page)) { + if (PageAnon(page) && PageSwapBacked(page) && + !PageSwapCache(page)) { if (!(sc->gfp_mask & __GFP_IO)) goto keep_locked; if (!add_to_swap(page, page_list)) @@ -1135,9 +1139,12 @@ static unsigned long shrink_page_list(struct list_head *page_list, * The page is mapped into the page tables of one or more * processes. Try to unmap it here. */ - if (page_mapped(page) && mapping) { + if (page_mapped(page)) { switch (ret = try_to_unmap(page, ttu_flags | TTU_BATCH_FLUSH)) { + case SWAP_DIRTY: + SetPageSwapBacked(page); + /* fall through */ case SWAP_FAIL: nr_unmap_fail++; goto activate_locked; @@ -1145,8 +1152,6 @@ static unsigned long shrink_page_list(struct list_head *page_list, goto keep_locked; case SWAP_MLOCK: goto cull_mlocked; - case SWAP_LZFREE: - goto lazyfree; case SWAP_SUCCESS: ; /* try to free the page below */ } @@ -1258,10 +1263,18 @@ static unsigned long shrink_page_list(struct list_head *page_list, } } -lazyfree: - if (!mapping || !__remove_mapping(mapping, page, true)) - goto keep_locked; + if (PageAnon(page) && !PageSwapBacked(page)) { + /* follow __remove_mapping for reference */ + if (!page_ref_freeze(page, 1)) + goto keep_locked; + if (PageDirty(page)) { + page_ref_unfreeze(page, 1); + goto keep_locked; + } + count_vm_event(PGLAZYFREED); + } else if (!mapping || !__remove_mapping(mapping, page, true)) + goto keep_locked; /* * At this point, we have no other references and there is * no way to pick any more up (removed from LRU, removed @@ -1271,9 +1284,6 @@ lazyfree: */ __ClearPageLocked(page); free_it: - if (ret == SWAP_LZFREE) - count_vm_event(PGLAZYFREED); - nr_reclaimed++; /*