The patch titled Subject: mm: rename _count, field of the struct page, to _refcount has been removed from the -mm tree. Its filename was mm-rename-_count-field-of-the-struct-page-to-_refcount.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Subject: mm: rename _count, field of the struct page, to _refcount Many developers already know that field for reference count of the struct page is _count and atomic type. They would try to handle it directly and this could break the purpose of page reference count tracepoint. To prevent direct _count modification, this patch rename it to _refcount and add warning message on the code. After that, developer who need to handle reference count will find that field should not be accessed directly. [akpm@xxxxxxxxxxxxxxxxxxxx: fix comments, per Vlastimil] [akpm@xxxxxxxxxxxxxxxxxxxx: Documentation/vm/transhuge.txt too] [sfr@xxxxxxxxxxxxxxxx: sync ethernet driver changes] Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Signed-off-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Johannes Berg <johannes@xxxxxxxxxxxxxxxx> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx> Cc: Sunil Goutham <sgoutham@xxxxxxxxxx> Cc: Chris Metcalf <cmetcalf@xxxxxxxxxxxx> Cc: Manish Chopra <manish.chopra@xxxxxxxxxx> Cc: Yuval Mintz <yuval.mintz@xxxxxxxxxx> Cc: Tariq Toukan <tariqt@xxxxxxxxxxxx> Cc: Saeed Mahameed <saeedm@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- Documentation/vm/transhuge.txt | 10 ++--- arch/tile/mm/init.c | 2 - drivers/block/aoe/aoecmd.c | 2 - drivers/hwtracing/intel_th/msu.c | 2 - drivers/net/ethernet/mellanox/mlx5/core/en_rx.c | 20 +++++----- drivers/net/ethernet/qlogic/qede/qede_main.c | 4 +- fs/proc/page.c | 2 - include/linux/mm.h | 2 - include/linux/mm_types.h | 14 ++++--- include/linux/page_ref.h | 26 +++++++------- include/linux/pagemap.h | 8 ++-- kernel/kexec_core.c | 2 - mm/huge_memory.c | 4 +- mm/internal.h | 2 - mm/page_alloc.c | 4 +- mm/slub.c | 4 +- mm/vmscan.c | 4 +- 17 files changed, 58 insertions(+), 54 deletions(-) diff -puN Documentation/vm/transhuge.txt~mm-rename-_count-field-of-the-struct-page-to-_refcount Documentation/vm/transhuge.txt --- a/Documentation/vm/transhuge.txt~mm-rename-_count-field-of-the-struct-page-to-_refcount +++ a/Documentation/vm/transhuge.txt @@ -394,9 +394,9 @@ hugepage natively. Once finished you can Refcounting on THP is mostly consistent with refcounting on other compound pages: - - get_page()/put_page() and GUP operate in head page's ->_count. + - get_page()/put_page() and GUP operate in head page's ->_refcount. - - ->_count in tail pages is always zero: get_page_unless_zero() never + - ->_refcount in tail pages is always zero: get_page_unless_zero() never succeed on tail pages. - map/unmap of the pages with PTE entry increment/decrement ->_mapcount @@ -426,15 +426,15 @@ requests to split pinned huge page: it e sum of mapcount of all sub-pages plus one (split_huge_page caller must have reference for head page). -split_huge_page uses migration entries to stabilize page->_count and +split_huge_page uses migration entries to stabilize page->_refcount and page->_mapcount. We safe against physical memory scanners too: the only legitimate way scanner can get reference to a page is get_page_unless_zero(). -All tail pages has zero ->_count until atomic_add(). It prevent scanner +All tail pages has zero ->_refcount until atomic_add(). It prevent scanner from geting reference to tail page up to the point. After the atomic_add() -we don't care about ->_count value. We already known how many references +we don't care about ->_refcount value. We already known how many references with should uncharge from head page. For head page get_page_unless_zero() will succeed and we don't mind. It's diff -puN arch/tile/mm/init.c~mm-rename-_count-field-of-the-struct-page-to-_refcount arch/tile/mm/init.c --- a/arch/tile/mm/init.c~mm-rename-_count-field-of-the-struct-page-to-_refcount +++ a/arch/tile/mm/init.c @@ -679,7 +679,7 @@ static void __init init_free_pfn_range(u * Hacky direct set to avoid unnecessary * lock take/release for EVERY page here. */ - p->_count.counter = 0; + p->_refcount.counter = 0; p->_mapcount.counter = -1; } init_page_count(page); diff -puN drivers/block/aoe/aoecmd.c~mm-rename-_count-field-of-the-struct-page-to-_refcount drivers/block/aoe/aoecmd.c --- a/drivers/block/aoe/aoecmd.c~mm-rename-_count-field-of-the-struct-page-to-_refcount +++ a/drivers/block/aoe/aoecmd.c @@ -861,7 +861,7 @@ rqbiocnt(struct request *r) * discussion. * * We cannot use get_page in the workaround, because it insists on a - * positive page count as a precondition. So we use _count directly. + * positive page count as a precondition. So we use _refcount directly. */ static void bio_pageinc(struct bio *bio) diff -puN drivers/hwtracing/intel_th/msu.c~mm-rename-_count-field-of-the-struct-page-to-_refcount drivers/hwtracing/intel_th/msu.c --- a/drivers/hwtracing/intel_th/msu.c~mm-rename-_count-field-of-the-struct-page-to-_refcount +++ a/drivers/hwtracing/intel_th/msu.c @@ -1164,7 +1164,7 @@ static void msc_mmap_close(struct vm_are if (!atomic_dec_and_mutex_lock(&msc->mmap_count, &msc->buf_mutex)) return; - /* drop page _counts */ + /* drop page _refcounts */ for (pg = 0; pg < msc->nr_pages; pg++) { struct page *page = msc_buffer_get_page(msc, pg); diff -puN drivers/net/ethernet/mellanox/mlx5/core/en_rx.c~mm-rename-_count-field-of-the-struct-page-to-_refcount drivers/net/ethernet/mellanox/mlx5/core/en_rx.c --- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c~mm-rename-_count-field-of-the-struct-page-to-_refcount +++ a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c @@ -433,8 +433,8 @@ static int mlx5e_alloc_rx_fragmented_mpw for (i = 0; i < MLX5_MPWRQ_PAGES_PER_WQE; i++) { if (unlikely(mlx5e_alloc_and_map_page(rq, wi, i))) goto err_unmap; - atomic_add(mlx5e_mpwqe_strides_per_page(rq), - &wi->umr.dma_info[i].page->_count); + page_ref_add(wi->umr.dma_info[i].page, + mlx5e_mpwqe_strides_per_page(rq)); wi->skbs_frags[i] = 0; } @@ -452,8 +452,8 @@ err_unmap: while (--i >= 0) { dma_unmap_page(rq->pdev, wi->umr.dma_info[i].addr, PAGE_SIZE, PCI_DMA_FROMDEVICE); - atomic_sub(mlx5e_mpwqe_strides_per_page(rq), - &wi->umr.dma_info[i].page->_count); + page_ref_sub(wi->umr.dma_info[i].page, + mlx5e_mpwqe_strides_per_page(rq)); put_page(wi->umr.dma_info[i].page); } dma_unmap_single(rq->pdev, wi->umr.mtt_addr, mtt_sz, PCI_DMA_TODEVICE); @@ -477,8 +477,8 @@ void mlx5e_free_rx_fragmented_mpwqe(stru for (i = 0; i < MLX5_MPWRQ_PAGES_PER_WQE; i++) { dma_unmap_page(rq->pdev, wi->umr.dma_info[i].addr, PAGE_SIZE, PCI_DMA_FROMDEVICE); - atomic_sub(mlx5e_mpwqe_strides_per_page(rq) - wi->skbs_frags[i], - &wi->umr.dma_info[i].page->_count); + page_ref_sub(wi->umr.dma_info[i].page, + mlx5e_mpwqe_strides_per_page(rq) - wi->skbs_frags[i]); put_page(wi->umr.dma_info[i].page); } dma_unmap_single(rq->pdev, wi->umr.mtt_addr, mtt_sz, PCI_DMA_TODEVICE); @@ -527,8 +527,8 @@ static int mlx5e_alloc_rx_linear_mpwqe(s */ split_page(wi->dma_info.page, MLX5_MPWRQ_WQE_PAGE_ORDER); for (i = 0; i < MLX5_MPWRQ_PAGES_PER_WQE; i++) { - atomic_add(mlx5e_mpwqe_strides_per_page(rq), - &wi->dma_info.page[i]._count); + page_ref_add(&wi->dma_info.page[i], + mlx5e_mpwqe_strides_per_page(rq)); wi->skbs_frags[i] = 0; } @@ -551,8 +551,8 @@ void mlx5e_free_rx_linear_mpwqe(struct m dma_unmap_page(rq->pdev, wi->dma_info.addr, rq->wqe_sz, PCI_DMA_FROMDEVICE); for (i = 0; i < MLX5_MPWRQ_PAGES_PER_WQE; i++) { - atomic_sub(mlx5e_mpwqe_strides_per_page(rq) - wi->skbs_frags[i], - &wi->dma_info.page[i]._count); + page_ref_sub(&wi->dma_info.page[i], + mlx5e_mpwqe_strides_per_page(rq) - wi->skbs_frags[i]); put_page(&wi->dma_info.page[i]); } } diff -puN drivers/net/ethernet/qlogic/qede/qede_main.c~mm-rename-_count-field-of-the-struct-page-to-_refcount drivers/net/ethernet/qlogic/qede/qede_main.c --- a/drivers/net/ethernet/qlogic/qede/qede_main.c~mm-rename-_count-field-of-the-struct-page-to-_refcount +++ a/drivers/net/ethernet/qlogic/qede/qede_main.c @@ -1036,7 +1036,7 @@ static int qede_fill_frag_skb(struct qed /* Incr page ref count to reuse on allocation failure * so that it doesn't get freed while freeing SKB. */ - atomic_inc(¤t_bd->data->_count); + page_ref_inc(current_bd->data); goto out; } @@ -1487,7 +1487,7 @@ static int qede_rx_int(struct qede_fastp * freeing SKB. */ - atomic_inc(&sw_rx_data->data->_count); + page_ref_inc(sw_rx_data->data); rxq->rx_alloc_errors++; qede_recycle_rx_bd_ring(rxq, edev, fp_cqe->bd_num); diff -puN fs/proc/page.c~mm-rename-_count-field-of-the-struct-page-to-_refcount fs/proc/page.c --- a/fs/proc/page.c~mm-rename-_count-field-of-the-struct-page-to-_refcount +++ a/fs/proc/page.c @@ -142,7 +142,7 @@ u64 stable_page_flags(struct page *page) /* - * Caveats on high order pages: page->_count will only be set + * Caveats on high order pages: page->_refcount will only be set * -1 on the head page; SLUB/SLQB do the same for PG_slab; * SLOB won't set PG_slab at all on compound pages. */ diff -puN include/linux/mm.h~mm-rename-_count-field-of-the-struct-page-to-_refcount include/linux/mm.h --- a/include/linux/mm.h~mm-rename-_count-field-of-the-struct-page-to-_refcount +++ a/include/linux/mm.h @@ -734,7 +734,7 @@ static inline void get_page(struct page page = compound_head(page); /* * Getting a normal page or the head of a compound page - * requires to already have an elevated page->_count. + * requires to already have an elevated page->_refcount. */ VM_BUG_ON_PAGE(page_ref_count(page) <= 0, page); page_ref_inc(page); diff -puN include/linux/mm_types.h~mm-rename-_count-field-of-the-struct-page-to-_refcount include/linux/mm_types.h --- a/include/linux/mm_types.h~mm-rename-_count-field-of-the-struct-page-to-_refcount +++ a/include/linux/mm_types.h @@ -73,9 +73,9 @@ struct page { unsigned long counters; #else /* - * Keep _count separate from slub cmpxchg_double data. - * As the rest of the double word is protected by - * slab_lock but _count is not. + * Keep _refcount separate from slub cmpxchg_double + * data. As the rest of the double word is protected by + * slab_lock but _refcount is not. */ unsigned counters; #endif @@ -97,7 +97,11 @@ struct page { }; int units; /* SLOB */ }; - atomic_t _count; /* Usage count, see below. */ + /* + * Usage count, *USE WRAPPER FUNCTION* + * when manual accounting. See page_ref.h + */ + atomic_t _refcount; }; unsigned int active; /* SLAB */ }; @@ -248,7 +252,7 @@ struct page_frag_cache { __u32 offset; #endif /* we maintain a pagecount bias, so that we dont dirty cache line - * containing page->_count every time we allocate a fragment. + * containing page->_refcount every time we allocate a fragment. */ unsigned int pagecnt_bias; bool pfmemalloc; diff -puN include/linux/page_ref.h~mm-rename-_count-field-of-the-struct-page-to-_refcount include/linux/page_ref.h --- a/include/linux/page_ref.h~mm-rename-_count-field-of-the-struct-page-to-_refcount +++ a/include/linux/page_ref.h @@ -63,17 +63,17 @@ static inline void __page_ref_unfreeze(s static inline int page_ref_count(struct page *page) { - return atomic_read(&page->_count); + return atomic_read(&page->_refcount); } static inline int page_count(struct page *page) { - return atomic_read(&compound_head(page)->_count); + return atomic_read(&compound_head(page)->_refcount); } static inline void set_page_count(struct page *page, int v) { - atomic_set(&page->_count, v); + atomic_set(&page->_refcount, v); if (page_ref_tracepoint_active(__tracepoint_page_ref_set)) __page_ref_set(page, v); } @@ -89,35 +89,35 @@ static inline void init_page_count(struc static inline void page_ref_add(struct page *page, int nr) { - atomic_add(nr, &page->_count); + atomic_add(nr, &page->_refcount); if (page_ref_tracepoint_active(__tracepoint_page_ref_mod)) __page_ref_mod(page, nr); } static inline void page_ref_sub(struct page *page, int nr) { - atomic_sub(nr, &page->_count); + atomic_sub(nr, &page->_refcount); if (page_ref_tracepoint_active(__tracepoint_page_ref_mod)) __page_ref_mod(page, -nr); } static inline void page_ref_inc(struct page *page) { - atomic_inc(&page->_count); + atomic_inc(&page->_refcount); if (page_ref_tracepoint_active(__tracepoint_page_ref_mod)) __page_ref_mod(page, 1); } static inline void page_ref_dec(struct page *page) { - atomic_dec(&page->_count); + atomic_dec(&page->_refcount); if (page_ref_tracepoint_active(__tracepoint_page_ref_mod)) __page_ref_mod(page, -1); } static inline int page_ref_sub_and_test(struct page *page, int nr) { - int ret = atomic_sub_and_test(nr, &page->_count); + int ret = atomic_sub_and_test(nr, &page->_refcount); if (page_ref_tracepoint_active(__tracepoint_page_ref_mod_and_test)) __page_ref_mod_and_test(page, -nr, ret); @@ -126,7 +126,7 @@ static inline int page_ref_sub_and_test( static inline int page_ref_dec_and_test(struct page *page) { - int ret = atomic_dec_and_test(&page->_count); + int ret = atomic_dec_and_test(&page->_refcount); if (page_ref_tracepoint_active(__tracepoint_page_ref_mod_and_test)) __page_ref_mod_and_test(page, -1, ret); @@ -135,7 +135,7 @@ static inline int page_ref_dec_and_test( static inline int page_ref_dec_return(struct page *page) { - int ret = atomic_dec_return(&page->_count); + int ret = atomic_dec_return(&page->_refcount); if (page_ref_tracepoint_active(__tracepoint_page_ref_mod_and_return)) __page_ref_mod_and_return(page, -1, ret); @@ -144,7 +144,7 @@ static inline int page_ref_dec_return(st static inline int page_ref_add_unless(struct page *page, int nr, int u) { - int ret = atomic_add_unless(&page->_count, nr, u); + int ret = atomic_add_unless(&page->_refcount, nr, u); if (page_ref_tracepoint_active(__tracepoint_page_ref_mod_unless)) __page_ref_mod_unless(page, nr, ret); @@ -153,7 +153,7 @@ static inline int page_ref_add_unless(st static inline int page_ref_freeze(struct page *page, int count) { - int ret = likely(atomic_cmpxchg(&page->_count, count, 0) == count); + int ret = likely(atomic_cmpxchg(&page->_refcount, count, 0) == count); if (page_ref_tracepoint_active(__tracepoint_page_ref_freeze)) __page_ref_freeze(page, count, ret); @@ -165,7 +165,7 @@ static inline void page_ref_unfreeze(str VM_BUG_ON_PAGE(page_count(page) != 0, page); VM_BUG_ON(count == 0); - atomic_set(&page->_count, count); + atomic_set(&page->_refcount, count); if (page_ref_tracepoint_active(__tracepoint_page_ref_unfreeze)) __page_ref_unfreeze(page, count); } diff -puN include/linux/pagemap.h~mm-rename-_count-field-of-the-struct-page-to-_refcount include/linux/pagemap.h --- a/include/linux/pagemap.h~mm-rename-_count-field-of-the-struct-page-to-_refcount +++ a/include/linux/pagemap.h @@ -90,12 +90,12 @@ void release_pages(struct page **pages, /* * speculatively take a reference to a page. - * If the page is free (_count == 0), then _count is untouched, and 0 - * is returned. Otherwise, _count is incremented by 1 and 1 is returned. + * If the page is free (_refcount == 0), then _refcount is untouched, and 0 + * is returned. Otherwise, _refcount is incremented by 1 and 1 is returned. * * This function must be called inside the same rcu_read_lock() section as has * been used to lookup the page in the pagecache radix-tree (or page table): - * this allows allocators to use a synchronize_rcu() to stabilize _count. + * this allows allocators to use a synchronize_rcu() to stabilize _refcount. * * Unless an RCU grace period has passed, the count of all pages coming out * of the allocator must be considered unstable. page_count may return higher @@ -111,7 +111,7 @@ void release_pages(struct page **pages, * 2. conditionally increment refcount * 3. check the page is still in pagecache (if no, goto 1) * - * Remove-side that cares about stability of _count (eg. reclaim) has the + * Remove-side that cares about stability of _refcount (eg. reclaim) has the * following (with tree_lock held for write): * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg) * B. remove page from pagecache diff -puN kernel/kexec_core.c~mm-rename-_count-field-of-the-struct-page-to-_refcount kernel/kexec_core.c --- a/kernel/kexec_core.c~mm-rename-_count-field-of-the-struct-page-to-_refcount +++ a/kernel/kexec_core.c @@ -1410,7 +1410,7 @@ static int __init crash_save_vmcoreinfo_ VMCOREINFO_STRUCT_SIZE(list_head); VMCOREINFO_SIZE(nodemask_t); VMCOREINFO_OFFSET(page, flags); - VMCOREINFO_OFFSET(page, _count); + VMCOREINFO_OFFSET(page, _refcount); VMCOREINFO_OFFSET(page, mapping); VMCOREINFO_OFFSET(page, lru); VMCOREINFO_OFFSET(page, _mapcount); diff -puN mm/huge_memory.c~mm-rename-_count-field-of-the-struct-page-to-_refcount mm/huge_memory.c --- a/mm/huge_memory.c~mm-rename-_count-field-of-the-struct-page-to-_refcount +++ a/mm/huge_memory.c @@ -3113,7 +3113,7 @@ static void __split_huge_page_tail(struc VM_BUG_ON_PAGE(page_ref_count(page_tail) != 0, page_tail); /* - * tail_page->_count is zero and not changing from under us. But + * tail_page->_refcount is zero and not changing from under us. But * get_page_unless_zero() may be running from under us on the * tail_page. If we used atomic_set() below instead of atomic_inc(), we * would then run atomic_set() concurrently with @@ -3340,7 +3340,7 @@ int split_huge_page_to_list(struct page if (mlocked) lru_add_drain(); - /* Prevent deferred_split_scan() touching ->_count */ + /* Prevent deferred_split_scan() touching ->_refcount */ spin_lock_irqsave(&pgdata->split_queue_lock, flags); count = page_count(head); mapcount = total_mapcount(head); diff -puN mm/internal.h~mm-rename-_count-field-of-the-struct-page-to-_refcount mm/internal.h --- a/mm/internal.h~mm-rename-_count-field-of-the-struct-page-to-_refcount +++ a/mm/internal.h @@ -58,7 +58,7 @@ static inline unsigned long ra_submit(st } /* - * Turn a non-refcounted page (->_count == 0) into refcounted with + * Turn a non-refcounted page (->_refcount == 0) into refcounted with * a count of one. */ static inline void set_page_refcounted(struct page *page) diff -puN mm/page_alloc.c~mm-rename-_count-field-of-the-struct-page-to-_refcount mm/page_alloc.c --- a/mm/page_alloc.c~mm-rename-_count-field-of-the-struct-page-to-_refcount +++ a/mm/page_alloc.c @@ -794,7 +794,7 @@ static inline int free_pages_check(struc if (unlikely(page->mapping != NULL)) bad_reason = "non-NULL mapping"; if (unlikely(page_ref_count(page) != 0)) - bad_reason = "nonzero _count"; + bad_reason = "nonzero _refcount"; if (unlikely(page->flags & PAGE_FLAGS_CHECK_AT_FREE)) { bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set"; bad_flags = PAGE_FLAGS_CHECK_AT_FREE; @@ -6864,7 +6864,7 @@ bool has_unmovable_pages(struct zone *zo * We can't use page_count without pin a page * because another CPU can free compound page. * This check already skips compound tails of THP - * because their page->_count is zero at all time. + * because their page->_refcount is zero at all time. */ if (!page_ref_count(page)) { if (PageBuddy(page)) diff -puN mm/slub.c~mm-rename-_count-field-of-the-struct-page-to-_refcount mm/slub.c --- a/mm/slub.c~mm-rename-_count-field-of-the-struct-page-to-_refcount +++ a/mm/slub.c @@ -329,8 +329,8 @@ static inline void set_page_slub_counter tmp.counters = counters_new; /* * page->counters can cover frozen/inuse/objects as well - * as page->_count. If we assign to ->counters directly - * we run the risk of losing updates to page->_count, so + * as page->_refcount. If we assign to ->counters directly + * we run the risk of losing updates to page->_refcount, so * be careful and only assign to the fields we need. */ page->frozen = tmp.frozen; diff -puN mm/vmscan.c~mm-rename-_count-field-of-the-struct-page-to-_refcount mm/vmscan.c --- a/mm/vmscan.c~mm-rename-_count-field-of-the-struct-page-to-_refcount +++ a/mm/vmscan.c @@ -633,7 +633,7 @@ static int __remove_mapping(struct addre * * Reversing the order of the tests ensures such a situation cannot * escape unnoticed. The smp_rmb is needed to ensure the page->flags - * load is not satisfied before that of page->_count. + * load is not satisfied before that of page->_refcount. * * Note that if SetPageDirty is always performed via set_page_dirty, * and thus under tree_lock, then this ordering is not required. @@ -1720,7 +1720,7 @@ shrink_inactive_list(unsigned long nr_to * It is safe to rely on PG_active against the non-LRU pages in here because * nobody will play with that bit on a non-LRU page. * - * The downside is that we have to touch page->_count against each page. + * The downside is that we have to touch page->_refcount against each page. * But we had to alter page->flags anyway. */ _ Patches currently in -mm which might be from iamjoonsoo.kim@xxxxxxx are -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html