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From: Roman Gushchin To: Andrew Morton Cc: Johannes Weiner , Michal Hocko , Shakeel Butt , Muchun Song , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Roman Gushchin Subject: [PATCH v2 04/14] mm: memcg: move charge migration code to memcontrol-v1.c Date: Mon, 24 Jun 2024 17:58:56 -0700 Message-ID: <20240625005906.106920-5-roman.gushchin@linux.dev> In-Reply-To: <20240625005906.106920-1-roman.gushchin@linux.dev> References: <20240625005906.106920-1-roman.gushchin@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: E2906140011 X-Stat-Signature: y4g1n4xonia9pyt94n5m5ddpot3tpb4q X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1719277176-280587 X-HE-Meta: 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 Cuhlr65M JX0PzOH0nL5Lhzg1/MxQu/BtiOEiFpc3Xyx1yQTJHbTlpqFwP/G3cOoyipgwhyfOw6xOo4lDwO5kR5NF3/A4yoTjKo8O6CGGagmU5+ENFsWN+jK7uKLM91oXTjbnkjDZOFbC1D1OyCQESzpAgPQGBlTQKJn9J17sJBtsioA5AYX/ARqI= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Unlike the legacy cgroup v1 memory controller, cgroup v2 memory controller doesn't support moving charged pages between cgroups. It's a fairly large and complicated code which created a number of problems in the past. Let's move this code into memcontrol-v1.c. It shaves off 1k lines from memcontrol.c. It's also another step towards making the legacy memory controller code optionally compiled. Signed-off-by: Roman Gushchin Acked-by: Michal Hocko --- mm/memcontrol-v1.c | 981 +++++++++++++++++++++++++++++++++++++++++++ mm/memcontrol-v1.h | 30 ++ mm/memcontrol.c | 1004 +------------------------------------------- 3 files changed, 1019 insertions(+), 996 deletions(-) diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c index 68e2f1a718d3..f4c8bec5ae1b 100644 --- a/mm/memcontrol-v1.c +++ b/mm/memcontrol-v1.c @@ -3,7 +3,12 @@ #include #include #include +#include +#include +#include +#include "internal.h" +#include "swap.h" #include "memcontrol-v1.h" /* @@ -30,6 +35,31 @@ static struct mem_cgroup_tree soft_limit_tree __read_mostly; #define MEM_CGROUP_MAX_RECLAIM_LOOPS 100 #define MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS 2 +/* Stuffs for move charges at task migration. */ +/* + * Types of charges to be moved. + */ +#define MOVE_ANON 0x1U +#define MOVE_FILE 0x2U +#define MOVE_MASK (MOVE_ANON | MOVE_FILE) + +/* "mc" and its members are protected by cgroup_mutex */ +static struct move_charge_struct { + spinlock_t lock; /* for from, to */ + struct mm_struct *mm; + struct mem_cgroup *from; + struct mem_cgroup *to; + unsigned long flags; + unsigned long precharge; + unsigned long moved_charge; + unsigned long moved_swap; + struct task_struct *moving_task; /* a task moving charges */ + wait_queue_head_t waitq; /* a waitq for other context */ +} mc = { + .lock = __SPIN_LOCK_UNLOCKED(mc.lock), + .waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq), +}; + static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_node *mz, struct mem_cgroup_tree_per_node *mctz, unsigned long new_usage_in_excess) @@ -325,6 +355,957 @@ unsigned long memcg1_soft_limit_reclaim(pg_data_t *pgdat, int order, return nr_reclaimed; } +/* + * A routine for checking "mem" is under move_account() or not. + * + * Checking a cgroup is mc.from or mc.to or under hierarchy of + * moving cgroups. This is for waiting at high-memory pressure + * caused by "move". + */ +static bool mem_cgroup_under_move(struct mem_cgroup *memcg) +{ + struct mem_cgroup *from; + struct mem_cgroup *to; + bool ret = false; + /* + * Unlike task_move routines, we access mc.to, mc.from not under + * mutual exclusion by cgroup_mutex. Here, we take spinlock instead. + */ + spin_lock(&mc.lock); + from = mc.from; + to = mc.to; + if (!from) + goto unlock; + + ret = mem_cgroup_is_descendant(from, memcg) || + mem_cgroup_is_descendant(to, memcg); +unlock: + spin_unlock(&mc.lock); + return ret; +} + +bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg) +{ + if (mc.moving_task && current != mc.moving_task) { + if (mem_cgroup_under_move(memcg)) { + DEFINE_WAIT(wait); + prepare_to_wait(&mc.waitq, &wait, TASK_INTERRUPTIBLE); + /* moving charge context might have finished. */ + if (mc.moving_task) + schedule(); + finish_wait(&mc.waitq, &wait); + return true; + } + } + return false; +} + +/** + * folio_memcg_lock - Bind a folio to its memcg. + * @folio: The folio. + * + * This function prevents unlocked LRU folios from being moved to + * another cgroup. + * + * It ensures lifetime of the bound memcg. The caller is responsible + * for the lifetime of the folio. + */ +void folio_memcg_lock(struct folio *folio) +{ + struct mem_cgroup *memcg; + unsigned long flags; + + /* + * The RCU lock is held throughout the transaction. The fast + * path can get away without acquiring the memcg->move_lock + * because page moving starts with an RCU grace period. + */ + rcu_read_lock(); + + if (mem_cgroup_disabled()) + return; +again: + memcg = folio_memcg(folio); + if (unlikely(!memcg)) + return; + +#ifdef CONFIG_PROVE_LOCKING + local_irq_save(flags); + might_lock(&memcg->move_lock); + local_irq_restore(flags); +#endif + + if (atomic_read(&memcg->moving_account) <= 0) + return; + + spin_lock_irqsave(&memcg->move_lock, flags); + if (memcg != folio_memcg(folio)) { + spin_unlock_irqrestore(&memcg->move_lock, flags); + goto again; + } + + /* + * When charge migration first begins, we can have multiple + * critical sections holding the fast-path RCU lock and one + * holding the slowpath move_lock. Track the task who has the + * move_lock for folio_memcg_unlock(). + */ + memcg->move_lock_task = current; + memcg->move_lock_flags = flags; +} + +static void __folio_memcg_unlock(struct mem_cgroup *memcg) +{ + if (memcg && memcg->move_lock_task == current) { + unsigned long flags = memcg->move_lock_flags; + + memcg->move_lock_task = NULL; + memcg->move_lock_flags = 0; + + spin_unlock_irqrestore(&memcg->move_lock, flags); + } + + rcu_read_unlock(); +} + +/** + * folio_memcg_unlock - Release the binding between a folio and its memcg. + * @folio: The folio. + * + * This releases the binding created by folio_memcg_lock(). This does + * not change the accounting of this folio to its memcg, but it does + * permit others to change it. + */ +void folio_memcg_unlock(struct folio *folio) +{ + __folio_memcg_unlock(folio_memcg(folio)); +} + +#ifdef CONFIG_SWAP +/** + * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record. + * @entry: swap entry to be moved + * @from: mem_cgroup which the entry is moved from + * @to: mem_cgroup which the entry is moved to + * + * It succeeds only when the swap_cgroup's record for this entry is the same + * as the mem_cgroup's id of @from. + * + * Returns 0 on success, -EINVAL on failure. + * + * The caller must have charged to @to, IOW, called page_counter_charge() about + * both res and memsw, and called css_get(). + */ +static int mem_cgroup_move_swap_account(swp_entry_t entry, + struct mem_cgroup *from, struct mem_cgroup *to) +{ + unsigned short old_id, new_id; + + old_id = mem_cgroup_id(from); + new_id = mem_cgroup_id(to); + + if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) { + mod_memcg_state(from, MEMCG_SWAP, -1); + mod_memcg_state(to, MEMCG_SWAP, 1); + return 0; + } + return -EINVAL; +} +#else +static inline int mem_cgroup_move_swap_account(swp_entry_t entry, + struct mem_cgroup *from, struct mem_cgroup *to) +{ + return -EINVAL; +} +#endif + +u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css, + struct cftype *cft) +{ + return mem_cgroup_from_css(css)->move_charge_at_immigrate; +} + +#ifdef CONFIG_MMU +int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css, + struct cftype *cft, u64 val) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(css); + + pr_warn_once("Cgroup memory moving (move_charge_at_immigrate) is deprecated. " + "Please report your usecase to linux-mm@kvack.org if you " + "depend on this functionality.\n"); + + if (val & ~MOVE_MASK) + return -EINVAL; + + /* + * No kind of locking is needed in here, because ->can_attach() will + * check this value once in the beginning of the process, and then carry + * on with stale data. This means that changes to this value will only + * affect task migrations starting after the change. + */ + memcg->move_charge_at_immigrate = val; + return 0; +} +#else +int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css, + struct cftype *cft, u64 val) +{ + return -ENOSYS; +} +#endif + +#ifdef CONFIG_MMU +/* Handlers for move charge at task migration. */ +static int mem_cgroup_do_precharge(unsigned long count) +{ + int ret; + + /* Try a single bulk charge without reclaim first, kswapd may wake */ + ret = try_charge(mc.to, GFP_KERNEL & ~__GFP_DIRECT_RECLAIM, count); + if (!ret) { + mc.precharge += count; + return ret; + } + + /* Try charges one by one with reclaim, but do not retry */ + while (count--) { + ret = try_charge(mc.to, GFP_KERNEL | __GFP_NORETRY, 1); + if (ret) + return ret; + mc.precharge++; + cond_resched(); + } + return 0; +} + +union mc_target { + struct folio *folio; + swp_entry_t ent; +}; + +enum mc_target_type { + MC_TARGET_NONE = 0, + MC_TARGET_PAGE, + MC_TARGET_SWAP, + MC_TARGET_DEVICE, +}; + +static struct page *mc_handle_present_pte(struct vm_area_struct *vma, + unsigned long addr, pte_t ptent) +{ + struct page *page = vm_normal_page(vma, addr, ptent); + + if (!page) + return NULL; + if (PageAnon(page)) { + if (!(mc.flags & MOVE_ANON)) + return NULL; + } else { + if (!(mc.flags & MOVE_FILE)) + return NULL; + } + get_page(page); + + return page; +} + +#if defined(CONFIG_SWAP) || defined(CONFIG_DEVICE_PRIVATE) +static struct page *mc_handle_swap_pte(struct vm_area_struct *vma, + pte_t ptent, swp_entry_t *entry) +{ + struct page *page = NULL; + swp_entry_t ent = pte_to_swp_entry(ptent); + + if (!(mc.flags & MOVE_ANON)) + return NULL; + + /* + * Handle device private pages that are not accessible by the CPU, but + * stored as special swap entries in the page table. + */ + if (is_device_private_entry(ent)) { + page = pfn_swap_entry_to_page(ent); + if (!get_page_unless_zero(page)) + return NULL; + return page; + } + + if (non_swap_entry(ent)) + return NULL; + + /* + * Because swap_cache_get_folio() updates some statistics counter, + * we call find_get_page() with swapper_space directly. + */ + page = find_get_page(swap_address_space(ent), swap_cache_index(ent)); + entry->val = ent.val; + + return page; +} +#else +static struct page *mc_handle_swap_pte(struct vm_area_struct *vma, + pte_t ptent, swp_entry_t *entry) +{ + return NULL; +} +#endif + +static struct page *mc_handle_file_pte(struct vm_area_struct *vma, + unsigned long addr, pte_t ptent) +{ + unsigned long index; + struct folio *folio; + + if (!vma->vm_file) /* anonymous vma */ + return NULL; + if (!(mc.flags & MOVE_FILE)) + return NULL; + + /* folio is moved even if it's not RSS of this task(page-faulted). */ + /* shmem/tmpfs may report page out on swap: account for that too. */ + index = linear_page_index(vma, addr); + folio = filemap_get_incore_folio(vma->vm_file->f_mapping, index); + if (IS_ERR(folio)) + return NULL; + return folio_file_page(folio, index); +} + +/** + * mem_cgroup_move_account - move account of the folio + * @folio: The folio. + * @compound: charge the page as compound or small page + * @from: mem_cgroup which the folio is moved from. + * @to: mem_cgroup which the folio is moved to. @from != @to. + * + * The folio must be locked and not on the LRU. + * + * This function doesn't do "charge" to new cgroup and doesn't do "uncharge" + * from old cgroup. + */ +static int mem_cgroup_move_account(struct folio *folio, + bool compound, + struct mem_cgroup *from, + struct mem_cgroup *to) +{ + struct lruvec *from_vec, *to_vec; + struct pglist_data *pgdat; + unsigned int nr_pages = compound ? folio_nr_pages(folio) : 1; + int nid, ret; + + VM_BUG_ON(from == to); + VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); + VM_BUG_ON_FOLIO(folio_test_lru(folio), folio); + VM_BUG_ON(compound && !folio_test_large(folio)); + + ret = -EINVAL; + if (folio_memcg(folio) != from) + goto out; + + pgdat = folio_pgdat(folio); + from_vec = mem_cgroup_lruvec(from, pgdat); + to_vec = mem_cgroup_lruvec(to, pgdat); + + folio_memcg_lock(folio); + + if (folio_test_anon(folio)) { + if (folio_mapped(folio)) { + __mod_lruvec_state(from_vec, NR_ANON_MAPPED, -nr_pages); + __mod_lruvec_state(to_vec, NR_ANON_MAPPED, nr_pages); + if (folio_test_pmd_mappable(folio)) { + __mod_lruvec_state(from_vec, NR_ANON_THPS, + -nr_pages); + __mod_lruvec_state(to_vec, NR_ANON_THPS, + nr_pages); + } + } + } else { + __mod_lruvec_state(from_vec, NR_FILE_PAGES, -nr_pages); + __mod_lruvec_state(to_vec, NR_FILE_PAGES, nr_pages); + + if (folio_test_swapbacked(folio)) { + __mod_lruvec_state(from_vec, NR_SHMEM, -nr_pages); + __mod_lruvec_state(to_vec, NR_SHMEM, nr_pages); + } + + if (folio_mapped(folio)) { + __mod_lruvec_state(from_vec, NR_FILE_MAPPED, -nr_pages); + __mod_lruvec_state(to_vec, NR_FILE_MAPPED, nr_pages); + } + + if (folio_test_dirty(folio)) { + struct address_space *mapping = folio_mapping(folio); + + if (mapping_can_writeback(mapping)) { + __mod_lruvec_state(from_vec, NR_FILE_DIRTY, + -nr_pages); + __mod_lruvec_state(to_vec, NR_FILE_DIRTY, + nr_pages); + } + } + } + +#ifdef CONFIG_SWAP + if (folio_test_swapcache(folio)) { + __mod_lruvec_state(from_vec, NR_SWAPCACHE, -nr_pages); + __mod_lruvec_state(to_vec, NR_SWAPCACHE, nr_pages); + } +#endif + if (folio_test_writeback(folio)) { + __mod_lruvec_state(from_vec, NR_WRITEBACK, -nr_pages); + __mod_lruvec_state(to_vec, NR_WRITEBACK, nr_pages); + } + + /* + * All state has been migrated, let's switch to the new memcg. + * + * It is safe to change page's memcg here because the page + * is referenced, charged, isolated, and locked: we can't race + * with (un)charging, migration, LRU putback, or anything else + * that would rely on a stable page's memory cgroup. + * + * Note that folio_memcg_lock is a memcg lock, not a page lock, + * to save space. As soon as we switch page's memory cgroup to a + * new memcg that isn't locked, the above state can change + * concurrently again. Make sure we're truly done with it. + */ + smp_mb(); + + css_get(&to->css); + css_put(&from->css); + + folio->memcg_data = (unsigned long)to; + + __folio_memcg_unlock(from); + + ret = 0; + nid = folio_nid(folio); + + local_irq_disable(); + mem_cgroup_charge_statistics(to, nr_pages); + memcg_check_events(to, nid); + mem_cgroup_charge_statistics(from, -nr_pages); + memcg_check_events(from, nid); + local_irq_enable(); +out: + return ret; +} + +/** + * get_mctgt_type - get target type of moving charge + * @vma: the vma the pte to be checked belongs + * @addr: the address corresponding to the pte to be checked + * @ptent: the pte to be checked + * @target: the pointer the target page or swap ent will be stored(can be NULL) + * + * Context: Called with pte lock held. + * Return: + * * MC_TARGET_NONE - If the pte is not a target for move charge. + * * MC_TARGET_PAGE - If the page corresponding to this pte is a target for + * move charge. If @target is not NULL, the folio is stored in target->folio + * with extra refcnt taken (Caller should release it). + * * MC_TARGET_SWAP - If the swap entry corresponding to this pte is a + * target for charge migration. If @target is not NULL, the entry is + * stored in target->ent. + * * MC_TARGET_DEVICE - Like MC_TARGET_PAGE but page is device memory and + * thus not on the lru. For now such page is charged like a regular page + * would be as it is just special memory taking the place of a regular page. + * See Documentations/vm/hmm.txt and include/linux/hmm.h + */ +static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma, + unsigned long addr, pte_t ptent, union mc_target *target) +{ + struct page *page = NULL; + struct folio *folio; + enum mc_target_type ret = MC_TARGET_NONE; + swp_entry_t ent = { .val = 0 }; + + if (pte_present(ptent)) + page = mc_handle_present_pte(vma, addr, ptent); + else if (pte_none_mostly(ptent)) + /* + * PTE markers should be treated as a none pte here, separated + * from other swap handling below. + */ + page = mc_handle_file_pte(vma, addr, ptent); + else if (is_swap_pte(ptent)) + page = mc_handle_swap_pte(vma, ptent, &ent); + + if (page) + folio = page_folio(page); + if (target && page) { + if (!folio_trylock(folio)) { + folio_put(folio); + return ret; + } + /* + * page_mapped() must be stable during the move. This + * pte is locked, so if it's present, the page cannot + * become unmapped. If it isn't, we have only partial + * control over the mapped state: the page lock will + * prevent new faults against pagecache and swapcache, + * so an unmapped page cannot become mapped. However, + * if the page is already mapped elsewhere, it can + * unmap, and there is nothing we can do about it. + * Alas, skip moving the page in this case. + */ + if (!pte_present(ptent) && page_mapped(page)) { + folio_unlock(folio); + folio_put(folio); + return ret; + } + } + + if (!page && !ent.val) + return ret; + if (page) { + /* + * Do only loose check w/o serialization. + * mem_cgroup_move_account() checks the page is valid or + * not under LRU exclusion. + */ + if (folio_memcg(folio) == mc.from) { + ret = MC_TARGET_PAGE; + if (folio_is_device_private(folio) || + folio_is_device_coherent(folio)) + ret = MC_TARGET_DEVICE; + if (target) + target->folio = folio; + } + if (!ret || !target) { + if (target) + folio_unlock(folio); + folio_put(folio); + } + } + /* + * There is a swap entry and a page doesn't exist or isn't charged. + * But we cannot move a tail-page in a THP. + */ + if (ent.val && !ret && (!page || !PageTransCompound(page)) && + mem_cgroup_id(mc.from) == lookup_swap_cgroup_id(ent)) { + ret = MC_TARGET_SWAP; + if (target) + target->ent = ent; + } + return ret; +} + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +/* + * We don't consider PMD mapped swapping or file mapped pages because THP does + * not support them for now. + * Caller should make sure that pmd_trans_huge(pmd) is true. + */ +static enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma, + unsigned long addr, pmd_t pmd, union mc_target *target) +{ + struct page *page = NULL; + struct folio *folio; + enum mc_target_type ret = MC_TARGET_NONE; + + if (unlikely(is_swap_pmd(pmd))) { + VM_BUG_ON(thp_migration_supported() && + !is_pmd_migration_entry(pmd)); + return ret; + } + page = pmd_page(pmd); + VM_BUG_ON_PAGE(!page || !PageHead(page), page); + folio = page_folio(page); + if (!(mc.flags & MOVE_ANON)) + return ret; + if (folio_memcg(folio) == mc.from) { + ret = MC_TARGET_PAGE; + if (target) { + folio_get(folio); + if (!folio_trylock(folio)) { + folio_put(folio); + return MC_TARGET_NONE; + } + target->folio = folio; + } + } + return ret; +} +#else +static inline enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma, + unsigned long addr, pmd_t pmd, union mc_target *target) +{ + return MC_TARGET_NONE; +} +#endif + +static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd, + unsigned long addr, unsigned long end, + struct mm_walk *walk) +{ + struct vm_area_struct *vma = walk->vma; + pte_t *pte; + spinlock_t *ptl; + + ptl = pmd_trans_huge_lock(pmd, vma); + if (ptl) { + /* + * Note their can not be MC_TARGET_DEVICE for now as we do not + * support transparent huge page with MEMORY_DEVICE_PRIVATE but + * this might change. + */ + if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE) + mc.precharge += HPAGE_PMD_NR; + spin_unlock(ptl); + return 0; + } + + pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); + if (!pte) + return 0; + for (; addr != end; pte++, addr += PAGE_SIZE) + if (get_mctgt_type(vma, addr, ptep_get(pte), NULL)) + mc.precharge++; /* increment precharge temporarily */ + pte_unmap_unlock(pte - 1, ptl); + cond_resched(); + + return 0; +} + +static const struct mm_walk_ops precharge_walk_ops = { + .pmd_entry = mem_cgroup_count_precharge_pte_range, + .walk_lock = PGWALK_RDLOCK, +}; + +static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm) +{ + unsigned long precharge; + + mmap_read_lock(mm); + walk_page_range(mm, 0, ULONG_MAX, &precharge_walk_ops, NULL); + mmap_read_unlock(mm); + + precharge = mc.precharge; + mc.precharge = 0; + + return precharge; +} + +static int mem_cgroup_precharge_mc(struct mm_struct *mm) +{ + unsigned long precharge = mem_cgroup_count_precharge(mm); + + VM_BUG_ON(mc.moving_task); + mc.moving_task = current; + return mem_cgroup_do_precharge(precharge); +} + +/* cancels all extra charges on mc.from and mc.to, and wakes up all waiters. */ +static void __mem_cgroup_clear_mc(void) +{ + struct mem_cgroup *from = mc.from; + struct mem_cgroup *to = mc.to; + + /* we must uncharge all the leftover precharges from mc.to */ + if (mc.precharge) { + mem_cgroup_cancel_charge(mc.to, mc.precharge); + mc.precharge = 0; + } + /* + * we didn't uncharge from mc.from at mem_cgroup_move_account(), so + * we must uncharge here. + */ + if (mc.moved_charge) { + mem_cgroup_cancel_charge(mc.from, mc.moved_charge); + mc.moved_charge = 0; + } + /* we must fixup refcnts and charges */ + if (mc.moved_swap) { + /* uncharge swap account from the old cgroup */ + if (!mem_cgroup_is_root(mc.from)) + page_counter_uncharge(&mc.from->memsw, mc.moved_swap); + + mem_cgroup_id_put_many(mc.from, mc.moved_swap); + + /* + * we charged both to->memory and to->memsw, so we + * should uncharge to->memory. + */ + if (!mem_cgroup_is_root(mc.to)) + page_counter_uncharge(&mc.to->memory, mc.moved_swap); + + mc.moved_swap = 0; + } + memcg_oom_recover(from); + memcg_oom_recover(to); + wake_up_all(&mc.waitq); +} + +static void mem_cgroup_clear_mc(void) +{ + struct mm_struct *mm = mc.mm; + + /* + * we must clear moving_task before waking up waiters at the end of + * task migration. + */ + mc.moving_task = NULL; + __mem_cgroup_clear_mc(); + spin_lock(&mc.lock); + mc.from = NULL; + mc.to = NULL; + mc.mm = NULL; + spin_unlock(&mc.lock); + + mmput(mm); +} + +int mem_cgroup_can_attach(struct cgroup_taskset *tset) +{ + struct cgroup_subsys_state *css; + struct mem_cgroup *memcg = NULL; /* unneeded init to make gcc happy */ + struct mem_cgroup *from; + struct task_struct *leader, *p; + struct mm_struct *mm; + unsigned long move_flags; + int ret = 0; + + /* charge immigration isn't supported on the default hierarchy */ + if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) + return 0; + + /* + * Multi-process migrations only happen on the default hierarchy + * where charge immigration is not used. Perform charge + * immigration if @tset contains a leader and whine if there are + * multiple. + */ + p = NULL; + cgroup_taskset_for_each_leader(leader, css, tset) { + WARN_ON_ONCE(p); + p = leader; + memcg = mem_cgroup_from_css(css); + } + if (!p) + return 0; + + /* + * We are now committed to this value whatever it is. Changes in this + * tunable will only affect upcoming migrations, not the current one. + * So we need to save it, and keep it going. + */ + move_flags = READ_ONCE(memcg->move_charge_at_immigrate); + if (!move_flags) + return 0; + + from = mem_cgroup_from_task(p); + + VM_BUG_ON(from == memcg); + + mm = get_task_mm(p); + if (!mm) + return 0; + /* We move charges only when we move a owner of the mm */ + if (mm->owner == p) { + VM_BUG_ON(mc.from); + VM_BUG_ON(mc.to); + VM_BUG_ON(mc.precharge); + VM_BUG_ON(mc.moved_charge); + VM_BUG_ON(mc.moved_swap); + + spin_lock(&mc.lock); + mc.mm = mm; + mc.from = from; + mc.to = memcg; + mc.flags = move_flags; + spin_unlock(&mc.lock); + /* We set mc.moving_task later */ + + ret = mem_cgroup_precharge_mc(mm); + if (ret) + mem_cgroup_clear_mc(); + } else { + mmput(mm); + } + return ret; +} + +void mem_cgroup_cancel_attach(struct cgroup_taskset *tset) +{ + if (mc.to) + mem_cgroup_clear_mc(); +} + +static int mem_cgroup_move_charge_pte_range(pmd_t *pmd, + unsigned long addr, unsigned long end, + struct mm_walk *walk) +{ + int ret = 0; + struct vm_area_struct *vma = walk->vma; + pte_t *pte; + spinlock_t *ptl; + enum mc_target_type target_type; + union mc_target target; + struct folio *folio; + + ptl = pmd_trans_huge_lock(pmd, vma); + if (ptl) { + if (mc.precharge < HPAGE_PMD_NR) { + spin_unlock(ptl); + return 0; + } + target_type = get_mctgt_type_thp(vma, addr, *pmd, &target); + if (target_type == MC_TARGET_PAGE) { + folio = target.folio; + if (folio_isolate_lru(folio)) { + if (!mem_cgroup_move_account(folio, true, + mc.from, mc.to)) { + mc.precharge -= HPAGE_PMD_NR; + mc.moved_charge += HPAGE_PMD_NR; + } + folio_putback_lru(folio); + } + folio_unlock(folio); + folio_put(folio); + } else if (target_type == MC_TARGET_DEVICE) { + folio = target.folio; + if (!mem_cgroup_move_account(folio, true, + mc.from, mc.to)) { + mc.precharge -= HPAGE_PMD_NR; + mc.moved_charge += HPAGE_PMD_NR; + } + folio_unlock(folio); + folio_put(folio); + } + spin_unlock(ptl); + return 0; + } + +retry: + pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); + if (!pte) + return 0; + for (; addr != end; addr += PAGE_SIZE) { + pte_t ptent = ptep_get(pte++); + bool device = false; + swp_entry_t ent; + + if (!mc.precharge) + break; + + switch (get_mctgt_type(vma, addr, ptent, &target)) { + case MC_TARGET_DEVICE: + device = true; + fallthrough; + case MC_TARGET_PAGE: + folio = target.folio; + /* + * We can have a part of the split pmd here. Moving it + * can be done but it would be too convoluted so simply + * ignore such a partial THP and keep it in original + * memcg. There should be somebody mapping the head. + */ + if (folio_test_large(folio)) + goto put; + if (!device && !folio_isolate_lru(folio)) + goto put; + if (!mem_cgroup_move_account(folio, false, + mc.from, mc.to)) { + mc.precharge--; + /* we uncharge from mc.from later. */ + mc.moved_charge++; + } + if (!device) + folio_putback_lru(folio); +put: /* get_mctgt_type() gets & locks the page */ + folio_unlock(folio); + folio_put(folio); + break; + case MC_TARGET_SWAP: + ent = target.ent; + if (!mem_cgroup_move_swap_account(ent, mc.from, mc.to)) { + mc.precharge--; + mem_cgroup_id_get_many(mc.to, 1); + /* we fixup other refcnts and charges later. */ + mc.moved_swap++; + } + break; + default: + break; + } + } + pte_unmap_unlock(pte - 1, ptl); + cond_resched(); + + if (addr != end) { + /* + * We have consumed all precharges we got in can_attach(). + * We try charge one by one, but don't do any additional + * charges to mc.to if we have failed in charge once in attach() + * phase. + */ + ret = mem_cgroup_do_precharge(1); + if (!ret) + goto retry; + } + + return ret; +} + +static const struct mm_walk_ops charge_walk_ops = { + .pmd_entry = mem_cgroup_move_charge_pte_range, + .walk_lock = PGWALK_RDLOCK, +}; + +static void mem_cgroup_move_charge(void) +{ + lru_add_drain_all(); + /* + * Signal folio_memcg_lock() to take the memcg's move_lock + * while we're moving its pages to another memcg. Then wait + * for already started RCU-only updates to finish. + */ + atomic_inc(&mc.from->moving_account); + synchronize_rcu(); +retry: + if (unlikely(!mmap_read_trylock(mc.mm))) { + /* + * Someone who are holding the mmap_lock might be waiting in + * waitq. So we cancel all extra charges, wake up all waiters, + * and retry. Because we cancel precharges, we might not be able + * to move enough charges, but moving charge is a best-effort + * feature anyway, so it wouldn't be a big problem. + */ + __mem_cgroup_clear_mc(); + cond_resched(); + goto retry; + } + /* + * When we have consumed all precharges and failed in doing + * additional charge, the page walk just aborts. + */ + walk_page_range(mc.mm, 0, ULONG_MAX, &charge_walk_ops, NULL); + mmap_read_unlock(mc.mm); + atomic_dec(&mc.from->moving_account); +} + +void mem_cgroup_move_task(void) +{ + if (mc.to) { + mem_cgroup_move_charge(); + mem_cgroup_clear_mc(); + } +} + +#else /* !CONFIG_MMU */ +static int mem_cgroup_can_attach(struct cgroup_taskset *tset) +{ + return 0; +} +static void mem_cgroup_cancel_attach(struct cgroup_taskset *tset) +{ +} +static void mem_cgroup_move_task(void) +{ +} +#endif + static int __init memcg1_init(void) { int node; diff --git a/mm/memcontrol-v1.h b/mm/memcontrol-v1.h index e37bc7e8d955..55e7c4f90c39 100644 --- a/mm/memcontrol-v1.h +++ b/mm/memcontrol-v1.h @@ -11,4 +11,34 @@ static inline void memcg1_soft_limit_reset(struct mem_cgroup *memcg) WRITE_ONCE(memcg->soft_limit, PAGE_COUNTER_MAX); } +void mem_cgroup_charge_statistics(struct mem_cgroup *memcg, int nr_pages); +void memcg_check_events(struct mem_cgroup *memcg, int nid); +void memcg_oom_recover(struct mem_cgroup *memcg); +int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask, + unsigned int nr_pages); + +static inline int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, + unsigned int nr_pages) +{ + if (mem_cgroup_is_root(memcg)) + return 0; + + return try_charge_memcg(memcg, gfp_mask, nr_pages); +} + +void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n); +void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n); + +bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg); +struct cgroup_taskset; +int mem_cgroup_can_attach(struct cgroup_taskset *tset); +void mem_cgroup_cancel_attach(struct cgroup_taskset *tset); +void mem_cgroup_move_task(void); + +struct cftype; +u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css, + struct cftype *cft); +int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css, + struct cftype *cft, u64 val); + #endif /* __MM_MEMCONTROL_V1_H */ diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 3479e1af12d5..3332c89cae2e 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -28,7 +28,6 @@ #include #include #include -#include #include #include #include @@ -45,7 +44,6 @@ #include #include #include -#include #include #include #include @@ -71,7 +69,6 @@ #include #include #include "slab.h" -#include "swap.h" #include "memcontrol-v1.h" #include @@ -158,31 +155,6 @@ struct mem_cgroup_event { static void mem_cgroup_threshold(struct mem_cgroup *memcg); static void mem_cgroup_oom_notify(struct mem_cgroup *memcg); -/* Stuffs for move charges at task migration. */ -/* - * Types of charges to be moved. - */ -#define MOVE_ANON 0x1U -#define MOVE_FILE 0x2U -#define MOVE_MASK (MOVE_ANON | MOVE_FILE) - -/* "mc" and its members are protected by cgroup_mutex */ -static struct move_charge_struct { - spinlock_t lock; /* for from, to */ - struct mm_struct *mm; - struct mem_cgroup *from; - struct mem_cgroup *to; - unsigned long flags; - unsigned long precharge; - unsigned long moved_charge; - unsigned long moved_swap; - struct task_struct *moving_task; /* a task moving charges */ - wait_queue_head_t waitq; /* a waitq for other context */ -} mc = { - .lock = __SPIN_LOCK_UNLOCKED(mc.lock), - .waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq), -}; - /* for encoding cft->private value on file */ enum res_type { _MEM, @@ -955,8 +927,7 @@ static unsigned long memcg_events_local(struct mem_cgroup *memcg, int event) return READ_ONCE(memcg->vmstats->events_local[i]); } -static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg, - int nr_pages) +void mem_cgroup_charge_statistics(struct mem_cgroup *memcg, int nr_pages) { /* pagein of a big page is an event. So, ignore page size */ if (nr_pages > 0) @@ -998,7 +969,7 @@ static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg, * Check events in order. * */ -static void memcg_check_events(struct mem_cgroup *memcg, int nid) +void memcg_check_events(struct mem_cgroup *memcg, int nid) { if (IS_ENABLED(CONFIG_PREEMPT_RT)) return; @@ -1467,51 +1438,6 @@ static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg) return margin; } -/* - * A routine for checking "mem" is under move_account() or not. - * - * Checking a cgroup is mc.from or mc.to or under hierarchy of - * moving cgroups. This is for waiting at high-memory pressure - * caused by "move". - */ -static bool mem_cgroup_under_move(struct mem_cgroup *memcg) -{ - struct mem_cgroup *from; - struct mem_cgroup *to; - bool ret = false; - /* - * Unlike task_move routines, we access mc.to, mc.from not under - * mutual exclusion by cgroup_mutex. Here, we take spinlock instead. - */ - spin_lock(&mc.lock); - from = mc.from; - to = mc.to; - if (!from) - goto unlock; - - ret = mem_cgroup_is_descendant(from, memcg) || - mem_cgroup_is_descendant(to, memcg); -unlock: - spin_unlock(&mc.lock); - return ret; -} - -static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg) -{ - if (mc.moving_task && current != mc.moving_task) { - if (mem_cgroup_under_move(memcg)) { - DEFINE_WAIT(wait); - prepare_to_wait(&mc.waitq, &wait, TASK_INTERRUPTIBLE); - /* moving charge context might have finished. */ - if (mc.moving_task) - schedule(); - finish_wait(&mc.waitq, &wait); - return true; - } - } - return false; -} - struct memory_stat { const char *name; unsigned int idx; @@ -1904,7 +1830,7 @@ static int memcg_oom_wake_function(wait_queue_entry_t *wait, return autoremove_wake_function(wait, mode, sync, arg); } -static void memcg_oom_recover(struct mem_cgroup *memcg) +void memcg_oom_recover(struct mem_cgroup *memcg) { /* * For the following lockless ->under_oom test, the only required @@ -2093,87 +2019,6 @@ void mem_cgroup_print_oom_group(struct mem_cgroup *memcg) pr_cont(" are going to be killed due to memory.oom.group set\n"); } -/** - * folio_memcg_lock - Bind a folio to its memcg. - * @folio: The folio. - * - * This function prevents unlocked LRU folios from being moved to - * another cgroup. - * - * It ensures lifetime of the bound memcg. The caller is responsible - * for the lifetime of the folio. - */ -void folio_memcg_lock(struct folio *folio) -{ - struct mem_cgroup *memcg; - unsigned long flags; - - /* - * The RCU lock is held throughout the transaction. The fast - * path can get away without acquiring the memcg->move_lock - * because page moving starts with an RCU grace period. - */ - rcu_read_lock(); - - if (mem_cgroup_disabled()) - return; -again: - memcg = folio_memcg(folio); - if (unlikely(!memcg)) - return; - -#ifdef CONFIG_PROVE_LOCKING - local_irq_save(flags); - might_lock(&memcg->move_lock); - local_irq_restore(flags); -#endif - - if (atomic_read(&memcg->moving_account) <= 0) - return; - - spin_lock_irqsave(&memcg->move_lock, flags); - if (memcg != folio_memcg(folio)) { - spin_unlock_irqrestore(&memcg->move_lock, flags); - goto again; - } - - /* - * When charge migration first begins, we can have multiple - * critical sections holding the fast-path RCU lock and one - * holding the slowpath move_lock. Track the task who has the - * move_lock for folio_memcg_unlock(). - */ - memcg->move_lock_task = current; - memcg->move_lock_flags = flags; -} - -static void __folio_memcg_unlock(struct mem_cgroup *memcg) -{ - if (memcg && memcg->move_lock_task == current) { - unsigned long flags = memcg->move_lock_flags; - - memcg->move_lock_task = NULL; - memcg->move_lock_flags = 0; - - spin_unlock_irqrestore(&memcg->move_lock, flags); - } - - rcu_read_unlock(); -} - -/** - * folio_memcg_unlock - Release the binding between a folio and its memcg. - * @folio: The folio. - * - * This releases the binding created by folio_memcg_lock(). This does - * not change the accounting of this folio to its memcg, but it does - * permit others to change it. - */ -void folio_memcg_unlock(struct folio *folio) -{ - __folio_memcg_unlock(folio_memcg(folio)); -} - struct memcg_stock_pcp { local_lock_t stock_lock; struct mem_cgroup *cached; /* this never be root cgroup */ @@ -2653,8 +2498,8 @@ void mem_cgroup_handle_over_high(gfp_t gfp_mask) css_put(&memcg->css); } -static int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask, - unsigned int nr_pages) +int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask, + unsigned int nr_pages) { unsigned int batch = max(MEMCG_CHARGE_BATCH, nr_pages); int nr_retries = MAX_RECLAIM_RETRIES; @@ -2849,15 +2694,6 @@ static int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask, return 0; } -static inline int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, - unsigned int nr_pages) -{ - if (mem_cgroup_is_root(memcg)) - return 0; - - return try_charge_memcg(memcg, gfp_mask, nr_pages); -} - /** * mem_cgroup_cancel_charge() - cancel an uncommitted try_charge() call. * @memcg: memcg previously charged. @@ -3595,43 +3431,6 @@ void split_page_memcg(struct page *head, int old_order, int new_order) css_get_many(&memcg->css, old_nr / new_nr - 1); } -#ifdef CONFIG_SWAP -/** - * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record. - * @entry: swap entry to be moved - * @from: mem_cgroup which the entry is moved from - * @to: mem_cgroup which the entry is moved to - * - * It succeeds only when the swap_cgroup's record for this entry is the same - * as the mem_cgroup's id of @from. - * - * Returns 0 on success, -EINVAL on failure. - * - * The caller must have charged to @to, IOW, called page_counter_charge() about - * both res and memsw, and called css_get(). - */ -static int mem_cgroup_move_swap_account(swp_entry_t entry, - struct mem_cgroup *from, struct mem_cgroup *to) -{ - unsigned short old_id, new_id; - - old_id = mem_cgroup_id(from); - new_id = mem_cgroup_id(to); - - if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) { - mod_memcg_state(from, MEMCG_SWAP, -1); - mod_memcg_state(to, MEMCG_SWAP, 1); - return 0; - } - return -EINVAL; -} -#else -static inline int mem_cgroup_move_swap_account(swp_entry_t entry, - struct mem_cgroup *from, struct mem_cgroup *to) -{ - return -EINVAL; -} -#endif static DEFINE_MUTEX(memcg_max_mutex); @@ -4015,42 +3814,6 @@ static ssize_t mem_cgroup_reset(struct kernfs_open_file *of, char *buf, return nbytes; } -static u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css, - struct cftype *cft) -{ - return mem_cgroup_from_css(css)->move_charge_at_immigrate; -} - -#ifdef CONFIG_MMU -static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css, - struct cftype *cft, u64 val) -{ - struct mem_cgroup *memcg = mem_cgroup_from_css(css); - - pr_warn_once("Cgroup memory moving (move_charge_at_immigrate) is deprecated. " - "Please report your usecase to linux-mm@kvack.org if you " - "depend on this functionality.\n"); - - if (val & ~MOVE_MASK) - return -EINVAL; - - /* - * No kind of locking is needed in here, because ->can_attach() will - * check this value once in the beginning of the process, and then carry - * on with stale data. This means that changes to this value will only - * affect task migrations starting after the change. - */ - memcg->move_charge_at_immigrate = val; - return 0; -} -#else -static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css, - struct cftype *cft, u64 val) -{ - return -ENOSYS; -} -#endif - #ifdef CONFIG_NUMA #define LRU_ALL_FILE (BIT(LRU_INACTIVE_FILE) | BIT(LRU_ACTIVE_FILE)) @@ -5261,13 +5024,13 @@ static void mem_cgroup_id_remove(struct mem_cgroup *memcg) } } -static void __maybe_unused mem_cgroup_id_get_many(struct mem_cgroup *memcg, - unsigned int n) +void __maybe_unused mem_cgroup_id_get_many(struct mem_cgroup *memcg, + unsigned int n) { refcount_add(n, &memcg->id.ref); } -static void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n) +void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n) { if (refcount_sub_and_test(n, &memcg->id.ref)) { mem_cgroup_id_remove(memcg); @@ -5747,757 +5510,6 @@ static void mem_cgroup_css_rstat_flush(struct cgroup_subsys_state *css, int cpu) atomic64_set(&memcg->vmstats->stats_updates, 0); } -#ifdef CONFIG_MMU -/* Handlers for move charge at task migration. */ -static int mem_cgroup_do_precharge(unsigned long count) -{ - int ret; - - /* Try a single bulk charge without reclaim first, kswapd may wake */ - ret = try_charge(mc.to, GFP_KERNEL & ~__GFP_DIRECT_RECLAIM, count); - if (!ret) { - mc.precharge += count; - return ret; - } - - /* Try charges one by one with reclaim, but do not retry */ - while (count--) { - ret = try_charge(mc.to, GFP_KERNEL | __GFP_NORETRY, 1); - if (ret) - return ret; - mc.precharge++; - cond_resched(); - } - return 0; -} - -union mc_target { - struct folio *folio; - swp_entry_t ent; -}; - -enum mc_target_type { - MC_TARGET_NONE = 0, - MC_TARGET_PAGE, - MC_TARGET_SWAP, - MC_TARGET_DEVICE, -}; - -static struct page *mc_handle_present_pte(struct vm_area_struct *vma, - unsigned long addr, pte_t ptent) -{ - struct page *page = vm_normal_page(vma, addr, ptent); - - if (!page) - return NULL; - if (PageAnon(page)) { - if (!(mc.flags & MOVE_ANON)) - return NULL; - } else { - if (!(mc.flags & MOVE_FILE)) - return NULL; - } - get_page(page); - - return page; -} - -#if defined(CONFIG_SWAP) || defined(CONFIG_DEVICE_PRIVATE) -static struct page *mc_handle_swap_pte(struct vm_area_struct *vma, - pte_t ptent, swp_entry_t *entry) -{ - struct page *page = NULL; - swp_entry_t ent = pte_to_swp_entry(ptent); - - if (!(mc.flags & MOVE_ANON)) - return NULL; - - /* - * Handle device private pages that are not accessible by the CPU, but - * stored as special swap entries in the page table. - */ - if (is_device_private_entry(ent)) { - page = pfn_swap_entry_to_page(ent); - if (!get_page_unless_zero(page)) - return NULL; - return page; - } - - if (non_swap_entry(ent)) - return NULL; - - /* - * Because swap_cache_get_folio() updates some statistics counter, - * we call find_get_page() with swapper_space directly. - */ - page = find_get_page(swap_address_space(ent), swap_cache_index(ent)); - entry->val = ent.val; - - return page; -} -#else -static struct page *mc_handle_swap_pte(struct vm_area_struct *vma, - pte_t ptent, swp_entry_t *entry) -{ - return NULL; -} -#endif - -static struct page *mc_handle_file_pte(struct vm_area_struct *vma, - unsigned long addr, pte_t ptent) -{ - unsigned long index; - struct folio *folio; - - if (!vma->vm_file) /* anonymous vma */ - return NULL; - if (!(mc.flags & MOVE_FILE)) - return NULL; - - /* folio is moved even if it's not RSS of this task(page-faulted). */ - /* shmem/tmpfs may report page out on swap: account for that too. */ - index = linear_page_index(vma, addr); - folio = filemap_get_incore_folio(vma->vm_file->f_mapping, index); - if (IS_ERR(folio)) - return NULL; - return folio_file_page(folio, index); -} - -/** - * mem_cgroup_move_account - move account of the folio - * @folio: The folio. - * @compound: charge the page as compound or small page - * @from: mem_cgroup which the folio is moved from. - * @to: mem_cgroup which the folio is moved to. @from != @to. - * - * The folio must be locked and not on the LRU. - * - * This function doesn't do "charge" to new cgroup and doesn't do "uncharge" - * from old cgroup. - */ -static int mem_cgroup_move_account(struct folio *folio, - bool compound, - struct mem_cgroup *from, - struct mem_cgroup *to) -{ - struct lruvec *from_vec, *to_vec; - struct pglist_data *pgdat; - unsigned int nr_pages = compound ? folio_nr_pages(folio) : 1; - int nid, ret; - - VM_BUG_ON(from == to); - VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); - VM_BUG_ON_FOLIO(folio_test_lru(folio), folio); - VM_BUG_ON(compound && !folio_test_large(folio)); - - ret = -EINVAL; - if (folio_memcg(folio) != from) - goto out; - - pgdat = folio_pgdat(folio); - from_vec = mem_cgroup_lruvec(from, pgdat); - to_vec = mem_cgroup_lruvec(to, pgdat); - - folio_memcg_lock(folio); - - if (folio_test_anon(folio)) { - if (folio_mapped(folio)) { - __mod_lruvec_state(from_vec, NR_ANON_MAPPED, -nr_pages); - __mod_lruvec_state(to_vec, NR_ANON_MAPPED, nr_pages); - if (folio_test_pmd_mappable(folio)) { - __mod_lruvec_state(from_vec, NR_ANON_THPS, - -nr_pages); - __mod_lruvec_state(to_vec, NR_ANON_THPS, - nr_pages); - } - } - } else { - __mod_lruvec_state(from_vec, NR_FILE_PAGES, -nr_pages); - __mod_lruvec_state(to_vec, NR_FILE_PAGES, nr_pages); - - if (folio_test_swapbacked(folio)) { - __mod_lruvec_state(from_vec, NR_SHMEM, -nr_pages); - __mod_lruvec_state(to_vec, NR_SHMEM, nr_pages); - } - - if (folio_mapped(folio)) { - __mod_lruvec_state(from_vec, NR_FILE_MAPPED, -nr_pages); - __mod_lruvec_state(to_vec, NR_FILE_MAPPED, nr_pages); - } - - if (folio_test_dirty(folio)) { - struct address_space *mapping = folio_mapping(folio); - - if (mapping_can_writeback(mapping)) { - __mod_lruvec_state(from_vec, NR_FILE_DIRTY, - -nr_pages); - __mod_lruvec_state(to_vec, NR_FILE_DIRTY, - nr_pages); - } - } - } - -#ifdef CONFIG_SWAP - if (folio_test_swapcache(folio)) { - __mod_lruvec_state(from_vec, NR_SWAPCACHE, -nr_pages); - __mod_lruvec_state(to_vec, NR_SWAPCACHE, nr_pages); - } -#endif - if (folio_test_writeback(folio)) { - __mod_lruvec_state(from_vec, NR_WRITEBACK, -nr_pages); - __mod_lruvec_state(to_vec, NR_WRITEBACK, nr_pages); - } - - /* - * All state has been migrated, let's switch to the new memcg. - * - * It is safe to change page's memcg here because the page - * is referenced, charged, isolated, and locked: we can't race - * with (un)charging, migration, LRU putback, or anything else - * that would rely on a stable page's memory cgroup. - * - * Note that folio_memcg_lock is a memcg lock, not a page lock, - * to save space. As soon as we switch page's memory cgroup to a - * new memcg that isn't locked, the above state can change - * concurrently again. Make sure we're truly done with it. - */ - smp_mb(); - - css_get(&to->css); - css_put(&from->css); - - folio->memcg_data = (unsigned long)to; - - __folio_memcg_unlock(from); - - ret = 0; - nid = folio_nid(folio); - - local_irq_disable(); - mem_cgroup_charge_statistics(to, nr_pages); - memcg_check_events(to, nid); - mem_cgroup_charge_statistics(from, -nr_pages); - memcg_check_events(from, nid); - local_irq_enable(); -out: - return ret; -} - -/** - * get_mctgt_type - get target type of moving charge - * @vma: the vma the pte to be checked belongs - * @addr: the address corresponding to the pte to be checked - * @ptent: the pte to be checked - * @target: the pointer the target page or swap ent will be stored(can be NULL) - * - * Context: Called with pte lock held. - * Return: - * * MC_TARGET_NONE - If the pte is not a target for move charge. - * * MC_TARGET_PAGE - If the page corresponding to this pte is a target for - * move charge. If @target is not NULL, the folio is stored in target->folio - * with extra refcnt taken (Caller should release it). - * * MC_TARGET_SWAP - If the swap entry corresponding to this pte is a - * target for charge migration. If @target is not NULL, the entry is - * stored in target->ent. - * * MC_TARGET_DEVICE - Like MC_TARGET_PAGE but page is device memory and - * thus not on the lru. For now such page is charged like a regular page - * would be as it is just special memory taking the place of a regular page. - * See Documentations/vm/hmm.txt and include/linux/hmm.h - */ -static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma, - unsigned long addr, pte_t ptent, union mc_target *target) -{ - struct page *page = NULL; - struct folio *folio; - enum mc_target_type ret = MC_TARGET_NONE; - swp_entry_t ent = { .val = 0 }; - - if (pte_present(ptent)) - page = mc_handle_present_pte(vma, addr, ptent); - else if (pte_none_mostly(ptent)) - /* - * PTE markers should be treated as a none pte here, separated - * from other swap handling below. - */ - page = mc_handle_file_pte(vma, addr, ptent); - else if (is_swap_pte(ptent)) - page = mc_handle_swap_pte(vma, ptent, &ent); - - if (page) - folio = page_folio(page); - if (target && page) { - if (!folio_trylock(folio)) { - folio_put(folio); - return ret; - } - /* - * page_mapped() must be stable during the move. This - * pte is locked, so if it's present, the page cannot - * become unmapped. If it isn't, we have only partial - * control over the mapped state: the page lock will - * prevent new faults against pagecache and swapcache, - * so an unmapped page cannot become mapped. However, - * if the page is already mapped elsewhere, it can - * unmap, and there is nothing we can do about it. - * Alas, skip moving the page in this case. - */ - if (!pte_present(ptent) && page_mapped(page)) { - folio_unlock(folio); - folio_put(folio); - return ret; - } - } - - if (!page && !ent.val) - return ret; - if (page) { - /* - * Do only loose check w/o serialization. - * mem_cgroup_move_account() checks the page is valid or - * not under LRU exclusion. - */ - if (folio_memcg(folio) == mc.from) { - ret = MC_TARGET_PAGE; - if (folio_is_device_private(folio) || - folio_is_device_coherent(folio)) - ret = MC_TARGET_DEVICE; - if (target) - target->folio = folio; - } - if (!ret || !target) { - if (target) - folio_unlock(folio); - folio_put(folio); - } - } - /* - * There is a swap entry and a page doesn't exist or isn't charged. - * But we cannot move a tail-page in a THP. - */ - if (ent.val && !ret && (!page || !PageTransCompound(page)) && - mem_cgroup_id(mc.from) == lookup_swap_cgroup_id(ent)) { - ret = MC_TARGET_SWAP; - if (target) - target->ent = ent; - } - return ret; -} - -#ifdef CONFIG_TRANSPARENT_HUGEPAGE -/* - * We don't consider PMD mapped swapping or file mapped pages because THP does - * not support them for now. - * Caller should make sure that pmd_trans_huge(pmd) is true. - */ -static enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma, - unsigned long addr, pmd_t pmd, union mc_target *target) -{ - struct page *page = NULL; - struct folio *folio; - enum mc_target_type ret = MC_TARGET_NONE; - - if (unlikely(is_swap_pmd(pmd))) { - VM_BUG_ON(thp_migration_supported() && - !is_pmd_migration_entry(pmd)); - return ret; - } - page = pmd_page(pmd); - VM_BUG_ON_PAGE(!page || !PageHead(page), page); - folio = page_folio(page); - if (!(mc.flags & MOVE_ANON)) - return ret; - if (folio_memcg(folio) == mc.from) { - ret = MC_TARGET_PAGE; - if (target) { - folio_get(folio); - if (!folio_trylock(folio)) { - folio_put(folio); - return MC_TARGET_NONE; - } - target->folio = folio; - } - } - return ret; -} -#else -static inline enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma, - unsigned long addr, pmd_t pmd, union mc_target *target) -{ - return MC_TARGET_NONE; -} -#endif - -static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd, - unsigned long addr, unsigned long end, - struct mm_walk *walk) -{ - struct vm_area_struct *vma = walk->vma; - pte_t *pte; - spinlock_t *ptl; - - ptl = pmd_trans_huge_lock(pmd, vma); - if (ptl) { - /* - * Note their can not be MC_TARGET_DEVICE for now as we do not - * support transparent huge page with MEMORY_DEVICE_PRIVATE but - * this might change. - */ - if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE) - mc.precharge += HPAGE_PMD_NR; - spin_unlock(ptl); - return 0; - } - - pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); - if (!pte) - return 0; - for (; addr != end; pte++, addr += PAGE_SIZE) - if (get_mctgt_type(vma, addr, ptep_get(pte), NULL)) - mc.precharge++; /* increment precharge temporarily */ - pte_unmap_unlock(pte - 1, ptl); - cond_resched(); - - return 0; -} - -static const struct mm_walk_ops precharge_walk_ops = { - .pmd_entry = mem_cgroup_count_precharge_pte_range, - .walk_lock = PGWALK_RDLOCK, -}; - -static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm) -{ - unsigned long precharge; - - mmap_read_lock(mm); - walk_page_range(mm, 0, ULONG_MAX, &precharge_walk_ops, NULL); - mmap_read_unlock(mm); - - precharge = mc.precharge; - mc.precharge = 0; - - return precharge; -} - -static int mem_cgroup_precharge_mc(struct mm_struct *mm) -{ - unsigned long precharge = mem_cgroup_count_precharge(mm); - - VM_BUG_ON(mc.moving_task); - mc.moving_task = current; - return mem_cgroup_do_precharge(precharge); -} - -/* cancels all extra charges on mc.from and mc.to, and wakes up all waiters. */ -static void __mem_cgroup_clear_mc(void) -{ - struct mem_cgroup *from = mc.from; - struct mem_cgroup *to = mc.to; - - /* we must uncharge all the leftover precharges from mc.to */ - if (mc.precharge) { - mem_cgroup_cancel_charge(mc.to, mc.precharge); - mc.precharge = 0; - } - /* - * we didn't uncharge from mc.from at mem_cgroup_move_account(), so - * we must uncharge here. - */ - if (mc.moved_charge) { - mem_cgroup_cancel_charge(mc.from, mc.moved_charge); - mc.moved_charge = 0; - } - /* we must fixup refcnts and charges */ - if (mc.moved_swap) { - /* uncharge swap account from the old cgroup */ - if (!mem_cgroup_is_root(mc.from)) - page_counter_uncharge(&mc.from->memsw, mc.moved_swap); - - mem_cgroup_id_put_many(mc.from, mc.moved_swap); - - /* - * we charged both to->memory and to->memsw, so we - * should uncharge to->memory. - */ - if (!mem_cgroup_is_root(mc.to)) - page_counter_uncharge(&mc.to->memory, mc.moved_swap); - - mc.moved_swap = 0; - } - memcg_oom_recover(from); - memcg_oom_recover(to); - wake_up_all(&mc.waitq); -} - -static void mem_cgroup_clear_mc(void) -{ - struct mm_struct *mm = mc.mm; - - /* - * we must clear moving_task before waking up waiters at the end of - * task migration. - */ - mc.moving_task = NULL; - __mem_cgroup_clear_mc(); - spin_lock(&mc.lock); - mc.from = NULL; - mc.to = NULL; - mc.mm = NULL; - spin_unlock(&mc.lock); - - mmput(mm); -} - -static int mem_cgroup_can_attach(struct cgroup_taskset *tset) -{ - struct cgroup_subsys_state *css; - struct mem_cgroup *memcg = NULL; /* unneeded init to make gcc happy */ - struct mem_cgroup *from; - struct task_struct *leader, *p; - struct mm_struct *mm; - unsigned long move_flags; - int ret = 0; - - /* charge immigration isn't supported on the default hierarchy */ - if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) - return 0; - - /* - * Multi-process migrations only happen on the default hierarchy - * where charge immigration is not used. Perform charge - * immigration if @tset contains a leader and whine if there are - * multiple. - */ - p = NULL; - cgroup_taskset_for_each_leader(leader, css, tset) { - WARN_ON_ONCE(p); - p = leader; - memcg = mem_cgroup_from_css(css); - } - if (!p) - return 0; - - /* - * We are now committed to this value whatever it is. Changes in this - * tunable will only affect upcoming migrations, not the current one. - * So we need to save it, and keep it going. - */ - move_flags = READ_ONCE(memcg->move_charge_at_immigrate); - if (!move_flags) - return 0; - - from = mem_cgroup_from_task(p); - - VM_BUG_ON(from == memcg); - - mm = get_task_mm(p); - if (!mm) - return 0; - /* We move charges only when we move a owner of the mm */ - if (mm->owner == p) { - VM_BUG_ON(mc.from); - VM_BUG_ON(mc.to); - VM_BUG_ON(mc.precharge); - VM_BUG_ON(mc.moved_charge); - VM_BUG_ON(mc.moved_swap); - - spin_lock(&mc.lock); - mc.mm = mm; - mc.from = from; - mc.to = memcg; - mc.flags = move_flags; - spin_unlock(&mc.lock); - /* We set mc.moving_task later */ - - ret = mem_cgroup_precharge_mc(mm); - if (ret) - mem_cgroup_clear_mc(); - } else { - mmput(mm); - } - return ret; -} - -static void mem_cgroup_cancel_attach(struct cgroup_taskset *tset) -{ - if (mc.to) - mem_cgroup_clear_mc(); -} - -static int mem_cgroup_move_charge_pte_range(pmd_t *pmd, - unsigned long addr, unsigned long end, - struct mm_walk *walk) -{ - int ret = 0; - struct vm_area_struct *vma = walk->vma; - pte_t *pte; - spinlock_t *ptl; - enum mc_target_type target_type; - union mc_target target; - struct folio *folio; - - ptl = pmd_trans_huge_lock(pmd, vma); - if (ptl) { - if (mc.precharge < HPAGE_PMD_NR) { - spin_unlock(ptl); - return 0; - } - target_type = get_mctgt_type_thp(vma, addr, *pmd, &target); - if (target_type == MC_TARGET_PAGE) { - folio = target.folio; - if (folio_isolate_lru(folio)) { - if (!mem_cgroup_move_account(folio, true, - mc.from, mc.to)) { - mc.precharge -= HPAGE_PMD_NR; - mc.moved_charge += HPAGE_PMD_NR; - } - folio_putback_lru(folio); - } - folio_unlock(folio); - folio_put(folio); - } else if (target_type == MC_TARGET_DEVICE) { - folio = target.folio; - if (!mem_cgroup_move_account(folio, true, - mc.from, mc.to)) { - mc.precharge -= HPAGE_PMD_NR; - mc.moved_charge += HPAGE_PMD_NR; - } - folio_unlock(folio); - folio_put(folio); - } - spin_unlock(ptl); - return 0; - } - -retry: - pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); - if (!pte) - return 0; - for (; addr != end; addr += PAGE_SIZE) { - pte_t ptent = ptep_get(pte++); - bool device = false; - swp_entry_t ent; - - if (!mc.precharge) - break; - - switch (get_mctgt_type(vma, addr, ptent, &target)) { - case MC_TARGET_DEVICE: - device = true; - fallthrough; - case MC_TARGET_PAGE: - folio = target.folio; - /* - * We can have a part of the split pmd here. Moving it - * can be done but it would be too convoluted so simply - * ignore such a partial THP and keep it in original - * memcg. There should be somebody mapping the head. - */ - if (folio_test_large(folio)) - goto put; - if (!device && !folio_isolate_lru(folio)) - goto put; - if (!mem_cgroup_move_account(folio, false, - mc.from, mc.to)) { - mc.precharge--; - /* we uncharge from mc.from later. */ - mc.moved_charge++; - } - if (!device) - folio_putback_lru(folio); -put: /* get_mctgt_type() gets & locks the page */ - folio_unlock(folio); - folio_put(folio); - break; - case MC_TARGET_SWAP: - ent = target.ent; - if (!mem_cgroup_move_swap_account(ent, mc.from, mc.to)) { - mc.precharge--; - mem_cgroup_id_get_many(mc.to, 1); - /* we fixup other refcnts and charges later. */ - mc.moved_swap++; - } - break; - default: - break; - } - } - pte_unmap_unlock(pte - 1, ptl); - cond_resched(); - - if (addr != end) { - /* - * We have consumed all precharges we got in can_attach(). - * We try charge one by one, but don't do any additional - * charges to mc.to if we have failed in charge once in attach() - * phase. - */ - ret = mem_cgroup_do_precharge(1); - if (!ret) - goto retry; - } - - return ret; -} - -static const struct mm_walk_ops charge_walk_ops = { - .pmd_entry = mem_cgroup_move_charge_pte_range, - .walk_lock = PGWALK_RDLOCK, -}; - -static void mem_cgroup_move_charge(void) -{ - lru_add_drain_all(); - /* - * Signal folio_memcg_lock() to take the memcg's move_lock - * while we're moving its pages to another memcg. Then wait - * for already started RCU-only updates to finish. - */ - atomic_inc(&mc.from->moving_account); - synchronize_rcu(); -retry: - if (unlikely(!mmap_read_trylock(mc.mm))) { - /* - * Someone who are holding the mmap_lock might be waiting in - * waitq. So we cancel all extra charges, wake up all waiters, - * and retry. Because we cancel precharges, we might not be able - * to move enough charges, but moving charge is a best-effort - * feature anyway, so it wouldn't be a big problem. - */ - __mem_cgroup_clear_mc(); - cond_resched(); - goto retry; - } - /* - * When we have consumed all precharges and failed in doing - * additional charge, the page walk just aborts. - */ - walk_page_range(mc.mm, 0, ULONG_MAX, &charge_walk_ops, NULL); - mmap_read_unlock(mc.mm); - atomic_dec(&mc.from->moving_account); -} - -static void mem_cgroup_move_task(void) -{ - if (mc.to) { - mem_cgroup_move_charge(); - mem_cgroup_clear_mc(); - } -} - -#else /* !CONFIG_MMU */ -static int mem_cgroup_can_attach(struct cgroup_taskset *tset) -{ - return 0; -} -static void mem_cgroup_cancel_attach(struct cgroup_taskset *tset) -{ -} -static void mem_cgroup_move_task(void) -{ -} -#endif - #ifdef CONFIG_MEMCG_KMEM static void mem_cgroup_fork(struct task_struct *task) {