[RFC PATCH 2/3] memcg-v1: remove charge move code

Shakeel Butt
2024-10-24T06:57:30Z

The memcg-v1 charge move feature has been deprecated completely and
let's remove the relevant code as well.

Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
---
include/linux/memcontrol.h | 5 -
mm/memcontrol-v1.c | 864 -------------------------------------
mm/memcontrol-v1.h | 6 -
mm/memcontrol.c | 9 -
4 files changed, 884 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 524006313b0d..798db70b0a30 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -299,11 +299,6 @@ struct mem_cgroup {
/* For oom notifier event fd */
struct list_head oom_notify;

- /*
- * Should we move charges of a task when a task is moved into this
- * mem_cgroup ? And what type of charges should we move ?
- */
- unsigned long move_charge_at_immigrate;
/* taken only while moving_account > 0 */
spinlock_t move_lock;
unsigned long move_lock_flags;
diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c
index 8f88540f0159..79339cb65b9d 100644
--- a/mm/memcontrol-v1.c
+++ b/mm/memcontrol-v1.c
@@ -40,31 +40,6 @@ 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 0x1ULL
-#define MOVE_FILE 0x2ULL
-#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 OOM */
struct mem_cgroup_eventfd_list {
struct list_head list;
@@ -426,51 +401,6 @@ 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 memcg1_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.
@@ -552,44 +482,6 @@ 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
-
static u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css,
struct cftype *cft)
{
@@ -600,8 +492,6 @@ static u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css,
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");
@@ -616,760 +506,6 @@ static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
}
#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);
-}
-
-static void memcg1_check_events(struct mem_cgroup *memcg, int nid);
-static void memcg1_charge_statistics(struct mem_cgroup *memcg, int nr_pages);
-
-/**
- * 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();
- memcg1_charge_statistics(to, nr_pages);
- memcg1_check_events(to, nid);
- memcg1_charge_statistics(from, -nr_pages);
- memcg1_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;
- }
- memcg1_oom_recover(from);
- memcg1_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 memcg1_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 memcg1_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 memcg1_move_task(void)
-{
- if (mc.to) {
- mem_cgroup_move_charge();
- mem_cgroup_clear_mc();
- }
-}
-
-#else /* !CONFIG_MMU */
-int memcg1_can_attach(struct cgroup_taskset *tset)
-{
- return 0;
-}
-void memcg1_cancel_attach(struct cgroup_taskset *tset)
-{
-}
-void memcg1_move_task(void)
-{
-}
-#endif
-
static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
{
struct mem_cgroup_threshold_ary *t;
diff --git a/mm/memcontrol-v1.h b/mm/memcontrol-v1.h
index c0672e25bcdb..0e3b82951d91 100644
--- a/mm/memcontrol-v1.h
+++ b/mm/memcontrol-v1.h
@@ -80,12 +80,7 @@ static inline void memcg1_soft_limit_reset(struct mem_cgroup *memcg)
WRITE_ONCE(memcg->soft_limit, PAGE_COUNTER_MAX);
}

-bool memcg1_wait_acct_move(struct mem_cgroup *memcg);
-
struct cgroup_taskset;
-int memcg1_can_attach(struct cgroup_taskset *tset);
-void memcg1_cancel_attach(struct cgroup_taskset *tset);
-void memcg1_move_task(void);
void memcg1_css_offline(struct mem_cgroup *memcg);

/* for encoding cft->private value on file */
@@ -130,7 +125,6 @@ static inline void memcg1_free_events(struct mem_cgroup *memcg) {}
static inline void memcg1_memcg_init(struct mem_cgroup *memcg) {}
static inline void memcg1_remove_from_trees(struct mem_cgroup *memcg) {}
static inline void memcg1_soft_limit_reset(struct mem_cgroup *memcg) {}
-static inline bool memcg1_wait_acct_move(struct mem_cgroup *memcg) { return false; }
static inline void memcg1_css_offline(struct mem_cgroup *memcg) {}

static inline bool memcg1_oom_prepare(struct mem_cgroup *memcg, bool *locked) { return true; }
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 5c3a8629ef3e..94279b9c766a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2242,12 +2242,6 @@ int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask,
*/
if (nr_reclaimed && nr_pages <= (1 << PAGE_ALLOC_COSTLY_ORDER))
goto retry;
- /*
- * At task move, charge accounts can be doubly counted. So, it's
- * better to wait until the end of task_move if something is going on.
- */
- if (memcg1_wait_acct_move(mem_over_limit))
- goto retry;

if (nr_retries--)
goto retry;
@@ -4439,9 +4433,6 @@ struct cgroup_subsys memory_cgrp_subsys = {
.exit = mem_cgroup_exit,
.dfl_cftypes = memory_files,
#ifdef CONFIG_MEMCG_V1
- .can_attach = memcg1_can_attach,
- .cancel_attach = memcg1_cancel_attach,
- .post_attach = memcg1_move_task,
.legacy_cftypes = mem_cgroup_legacy_files,
#endif
.early_init = 0,
--
2.43.5