memcg: move charges of anonymous page
This patch is the core part of this move-charge-at-task-migration feature. It implements functions to move charges of anonymous pages mapped only by the target task. Implementation: - define struct move_charge_struct and a valuable of it(mc) to remember the count of pre-charges and other information. - At can_attach(), get anon_rss of the target mm, call __mem_cgroup_try_charge() repeatedly and count up mc.precharge. - At attach(), parse the page table, find a target page to be move, and call mem_cgroup_move_account() about the page. - Cancel all precharges if mc.precharge > 0 on failure or at the end of task move. [akpm@linux-foundation.org: a little simplification] Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Paul Menage <menage@google.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>hifive-unleashed-5.1
Daisuke Nishimura
Linus Torvalds
parent
7dc74be032
commit
4ffef5feff
292
mm/memcontrol.c
292
mm/memcontrol.c
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@ -21,6 +21,7 @@
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#include <linux/memcontrol.h>
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#include <linux/cgroup.h>
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#include <linux/mm.h>
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#include <linux/hugetlb.h>
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#include <linux/pagemap.h>
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#include <linux/smp.h>
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#include <linux/page-flags.h>
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@ -243,9 +244,17 @@ struct mem_cgroup {
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* left-shifted bitmap of these types.
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*/
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enum move_type {
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MOVE_CHARGE_TYPE_ANON, /* private anonymous page and swap of it */
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NR_MOVE_TYPE,
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};
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/* "mc" and its members are protected by cgroup_mutex */
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static struct move_charge_struct {
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struct mem_cgroup *from;
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struct mem_cgroup *to;
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unsigned long precharge;
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} mc;
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/*
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* Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft
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* limit reclaim to prevent infinite loops, if they ever occur.
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@ -1513,7 +1522,7 @@ charged:
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* Insert ancestor (and ancestor's ancestors), to softlimit RB-tree.
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* if they exceeds softlimit.
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*/
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if (mem_cgroup_soft_limit_check(mem))
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if (page && mem_cgroup_soft_limit_check(mem))
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mem_cgroup_update_tree(mem, page);
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done:
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return 0;
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@ -1690,8 +1699,9 @@ static void __mem_cgroup_move_account(struct page_cgroup *pc,
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/*
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* We charges against "to" which may not have any tasks. Then, "to"
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* can be under rmdir(). But in current implementation, caller of
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* this function is just force_empty() and it's garanteed that
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* "to" is never removed. So, we don't check rmdir status here.
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* this function is just force_empty() and move charge, so it's
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* garanteed that "to" is never removed. So, we don't check rmdir
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* status here.
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*/
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}
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@ -3428,11 +3438,171 @@ static int mem_cgroup_populate(struct cgroup_subsys *ss,
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}
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/* Handlers for move charge at task migration. */
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static int mem_cgroup_can_move_charge(void)
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static int mem_cgroup_do_precharge(void)
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{
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int ret = -ENOMEM;
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struct mem_cgroup *mem = mc.to;
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ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false, NULL);
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if (ret || !mem)
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return -ENOMEM;
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mc.precharge++;
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return ret;
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}
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/**
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* is_target_pte_for_mc - check a pte whether it is valid for move charge
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* @vma: the vma the pte to be checked belongs
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* @addr: the address corresponding to the pte to be checked
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* @ptent: the pte to be checked
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* @target: the pointer the target page will be stored(can be NULL)
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*
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* Returns
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* 0(MC_TARGET_NONE): if the pte is not a target for move charge.
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* 1(MC_TARGET_PAGE): if the page corresponding to this pte is a target for
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* move charge. if @target is not NULL, the page is stored in target->page
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* with extra refcnt got(Callers should handle it).
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*
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* Called with pte lock held.
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*/
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/* We add a new member later. */
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union mc_target {
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struct page *page;
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};
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/* We add a new type later. */
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enum mc_target_type {
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MC_TARGET_NONE, /* not used */
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MC_TARGET_PAGE,
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};
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static int is_target_pte_for_mc(struct vm_area_struct *vma,
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unsigned long addr, pte_t ptent, union mc_target *target)
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{
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struct page *page;
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struct page_cgroup *pc;
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int ret = 0;
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bool move_anon = test_bit(MOVE_CHARGE_TYPE_ANON,
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&mc.to->move_charge_at_immigrate);
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if (!pte_present(ptent))
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return 0;
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page = vm_normal_page(vma, addr, ptent);
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if (!page || !page_mapped(page))
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return 0;
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/*
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* TODO: We don't move charges of file(including shmem/tmpfs) pages for
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* now.
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*/
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if (!move_anon || !PageAnon(page))
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return 0;
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/*
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* TODO: We don't move charges of shared(used by multiple processes)
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* pages for now.
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*/
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if (page_mapcount(page) > 1)
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return 0;
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if (!get_page_unless_zero(page))
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return 0;
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pc = lookup_page_cgroup(page);
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/*
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* Do only loose check w/o page_cgroup lock. mem_cgroup_move_account()
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* checks the pc is valid or not under the lock.
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*/
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if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) {
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ret = MC_TARGET_PAGE;
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if (target)
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target->page = page;
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}
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if (!ret || !target)
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put_page(page);
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return ret;
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}
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static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
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unsigned long addr, unsigned long end,
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struct mm_walk *walk)
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{
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struct vm_area_struct *vma = walk->private;
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pte_t *pte;
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spinlock_t *ptl;
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pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
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for (; addr != end; pte++, addr += PAGE_SIZE)
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if (is_target_pte_for_mc(vma, addr, *pte, NULL))
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mc.precharge++; /* increment precharge temporarily */
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pte_unmap_unlock(pte - 1, ptl);
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cond_resched();
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return 0;
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}
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static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
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{
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unsigned long precharge;
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struct vm_area_struct *vma;
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down_read(&mm->mmap_sem);
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for (vma = mm->mmap; vma; vma = vma->vm_next) {
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struct mm_walk mem_cgroup_count_precharge_walk = {
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.pmd_entry = mem_cgroup_count_precharge_pte_range,
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.mm = mm,
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.private = vma,
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};
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if (is_vm_hugetlb_page(vma))
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continue;
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/* TODO: We don't move charges of shmem/tmpfs pages for now. */
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if (vma->vm_flags & VM_SHARED)
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continue;
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walk_page_range(vma->vm_start, vma->vm_end,
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&mem_cgroup_count_precharge_walk);
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}
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up_read(&mm->mmap_sem);
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precharge = mc.precharge;
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mc.precharge = 0;
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return precharge;
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}
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#define PRECHARGE_AT_ONCE 256
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static int mem_cgroup_precharge_mc(struct mm_struct *mm)
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{
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int ret = 0;
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int count = PRECHARGE_AT_ONCE;
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unsigned long precharge = mem_cgroup_count_precharge(mm);
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while (!ret && precharge--) {
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if (signal_pending(current)) {
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ret = -EINTR;
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break;
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}
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if (!count--) {
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count = PRECHARGE_AT_ONCE;
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cond_resched();
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}
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ret = mem_cgroup_do_precharge();
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}
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return ret;
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}
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static void mem_cgroup_clear_mc(void)
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{
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/* we must uncharge all the leftover precharges from mc.to */
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while (mc.precharge) {
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mem_cgroup_cancel_charge(mc.to);
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mc.precharge--;
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}
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mc.from = NULL;
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mc.to = NULL;
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}
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static int mem_cgroup_can_attach(struct cgroup_subsys *ss,
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struct cgroup *cgroup,
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struct task_struct *p,
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@ -3450,11 +3620,19 @@ static int mem_cgroup_can_attach(struct cgroup_subsys *ss,
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mm = get_task_mm(p);
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if (!mm)
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return 0;
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/* We move charges only when we move a owner of the mm */
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if (mm->owner == p)
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ret = mem_cgroup_can_move_charge();
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if (mm->owner == p) {
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VM_BUG_ON(mc.from);
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VM_BUG_ON(mc.to);
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VM_BUG_ON(mc.precharge);
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mc.from = from;
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mc.to = mem;
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mc.precharge = 0;
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ret = mem_cgroup_precharge_mc(mm);
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if (ret)
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mem_cgroup_clear_mc();
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}
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mmput(mm);
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}
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return ret;
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@ -3465,10 +3643,95 @@ static void mem_cgroup_cancel_attach(struct cgroup_subsys *ss,
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struct task_struct *p,
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bool threadgroup)
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{
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mem_cgroup_clear_mc();
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}
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static void mem_cgroup_move_charge(void)
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static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
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unsigned long addr, unsigned long end,
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struct mm_walk *walk)
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{
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int ret = 0;
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struct vm_area_struct *vma = walk->private;
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pte_t *pte;
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spinlock_t *ptl;
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retry:
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pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
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for (; addr != end; addr += PAGE_SIZE) {
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pte_t ptent = *(pte++);
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union mc_target target;
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int type;
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struct page *page;
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struct page_cgroup *pc;
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if (!mc.precharge)
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break;
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type = is_target_pte_for_mc(vma, addr, ptent, &target);
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switch (type) {
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case MC_TARGET_PAGE:
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page = target.page;
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if (isolate_lru_page(page))
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goto put;
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pc = lookup_page_cgroup(page);
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if (!mem_cgroup_move_account(pc, mc.from, mc.to)) {
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css_put(&mc.to->css);
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mc.precharge--;
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}
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putback_lru_page(page);
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put: /* is_target_pte_for_mc() gets the page */
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put_page(page);
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break;
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default:
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break;
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}
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}
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pte_unmap_unlock(pte - 1, ptl);
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cond_resched();
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if (addr != end) {
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/*
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* We have consumed all precharges we got in can_attach().
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* We try charge one by one, but don't do any additional
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* charges to mc.to if we have failed in charge once in attach()
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* phase.
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*/
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ret = mem_cgroup_do_precharge();
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if (!ret)
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goto retry;
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}
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return ret;
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}
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static void mem_cgroup_move_charge(struct mm_struct *mm)
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{
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struct vm_area_struct *vma;
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lru_add_drain_all();
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down_read(&mm->mmap_sem);
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for (vma = mm->mmap; vma; vma = vma->vm_next) {
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int ret;
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struct mm_walk mem_cgroup_move_charge_walk = {
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.pmd_entry = mem_cgroup_move_charge_pte_range,
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.mm = mm,
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.private = vma,
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};
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if (is_vm_hugetlb_page(vma))
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continue;
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/* TODO: We don't move charges of shmem/tmpfs pages for now. */
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if (vma->vm_flags & VM_SHARED)
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continue;
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ret = walk_page_range(vma->vm_start, vma->vm_end,
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&mem_cgroup_move_charge_walk);
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if (ret)
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/*
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* means we have consumed all precharges and failed in
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* doing additional charge. Just abandon here.
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*/
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break;
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}
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up_read(&mm->mmap_sem);
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}
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static void mem_cgroup_move_task(struct cgroup_subsys *ss,
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@ -3477,7 +3740,18 @@ static void mem_cgroup_move_task(struct cgroup_subsys *ss,
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struct task_struct *p,
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bool threadgroup)
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{
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mem_cgroup_move_charge();
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struct mm_struct *mm;
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if (!mc.to)
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/* no need to move charge */
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return;
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mm = get_task_mm(p);
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if (mm) {
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mem_cgroup_move_charge(mm);
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mmput(mm);
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}
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mem_cgroup_clear_mc();
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}
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struct cgroup_subsys mem_cgroup_subsys = {
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