8.2 Type of charges which can be move
Each bits of move_charge_at_immigrate has its own meaning about what type of
-charges should be moved.
+charges should be moved. But in any cases, it must be noted that an account of
+a page or a swap can be moved only when it is charged to the task's current(old)
+memory cgroup.
bit | what type of charges would be moved ?
-----+------------------------------------------------------------------------
0 | A charge of an anonymous page(or swap of it) used by the target task.
| Those pages and swaps must be used only by the target task. You must
| enable Swap Extension(see 2.4) to enable move of swap charges.
-
-Note: Those pages and swaps must be charged to the old cgroup.
-Note: More type of pages(e.g. file cache, shmem,) will be supported by other
- bits in future.
+ -----+------------------------------------------------------------------------
+ 1 | A charge of file pages(normal file, tmpfs file(e.g. ipc shared memory)
+ | and swaps of tmpfs file) mmaped by the target task. Unlike the case of
+ | anonymous pages, file pages(and swaps) in the range mmapped by the task
+ | will be moved even if the task hasn't done page fault, i.e. they might
+ | not be the task's "RSS", but other task's "RSS" that maps the same file.
+ | And mapcount of the page is ignored(the page can be moved even if
+ | page_mapcount(page) > 1). You must enable Swap Extension(see 2.4) to
+ | enable move of swap charges.
8.3 TODO
-- Add support for other types of pages(e.g. file cache, shmem, etc.).
- Implement madvise(2) to let users decide the vma to be moved or not to be
moved.
- All of moving charge operations are done under cgroup_mutex. It's not good
extern int shmem_unuse(swp_entry_t entry, struct page *page);
#endif /* CONFIG_MMU */
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR
+extern void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
+ struct page **pagep, swp_entry_t *ent);
+#endif
+
extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
#ifdef CONFIG_SWAP
*/
enum move_type {
MOVE_CHARGE_TYPE_ANON, /* private anonymous page and swap of it */
+ MOVE_CHARGE_TYPE_FILE, /* file page(including tmpfs) and swap of it */
NR_MOVE_TYPE,
};
&mc.to->move_charge_at_immigrate);
}
+static bool move_file(void)
+{
+ return test_bit(MOVE_CHARGE_TYPE_FILE,
+ &mc.to->move_charge_at_immigrate);
+}
+
/*
* Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft
* limit reclaim to prevent infinite loops, if they ever occur.
/* we don't move shared anon */
if (!move_anon() || page_mapcount(page) > 2)
return NULL;
- } else
- /*
- * TODO: We don't move charges of file(including shmem/tmpfs)
- * pages for now.
- */
+ } else if (!move_file())
+ /* we ignore mapcount for file pages */
return NULL;
if (!get_page_unless_zero(page))
return NULL;
return page;
}
+static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
+ unsigned long addr, pte_t ptent, swp_entry_t *entry)
+{
+ struct page *page = NULL;
+ struct inode *inode;
+ struct address_space *mapping;
+ pgoff_t pgoff;
+
+ if (!vma->vm_file) /* anonymous vma */
+ return NULL;
+ if (!move_file())
+ return NULL;
+
+ inode = vma->vm_file->f_path.dentry->d_inode;
+ mapping = vma->vm_file->f_mapping;
+ if (pte_none(ptent))
+ pgoff = linear_page_index(vma, addr);
+ else /* pte_file(ptent) is true */
+ pgoff = pte_to_pgoff(ptent);
+
+ /* page is moved even if it's not RSS of this task(page-faulted). */
+ if (!mapping_cap_swap_backed(mapping)) { /* normal file */
+ page = find_get_page(mapping, pgoff);
+ } else { /* shmem/tmpfs file. we should take account of swap too. */
+ swp_entry_t ent;
+ mem_cgroup_get_shmem_target(inode, pgoff, &page, &ent);
+ if (do_swap_account)
+ entry->val = ent.val;
+ }
+
+ return page;
+}
+
static int is_target_pte_for_mc(struct vm_area_struct *vma,
unsigned long addr, pte_t ptent, union mc_target *target)
{
page = mc_handle_present_pte(vma, addr, ptent);
else if (is_swap_pte(ptent))
page = mc_handle_swap_pte(vma, addr, ptent, &ent);
- /* TODO: handle swap of shmes/tmpfs */
+ else if (pte_none(ptent) || pte_file(ptent))
+ page = mc_handle_file_pte(vma, addr, ptent, &ent);
if (!page && !ent.val)
return 0;
};
if (is_vm_hugetlb_page(vma))
continue;
- /* TODO: We don't move charges of shmem/tmpfs pages for now. */
- if (vma->vm_flags & VM_SHARED)
- continue;
walk_page_range(vma->vm_start, vma->vm_end,
&mem_cgroup_count_precharge_walk);
}
};
if (is_vm_hugetlb_page(vma))
continue;
- /* TODO: We don't move charges of shmem/tmpfs pages for now. */
- if (vma->vm_flags & VM_SHARED)
- continue;
ret = walk_page_range(vma->vm_start, vma->vm_end,
&mem_cgroup_move_charge_walk);
if (ret)
return error;
}
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR
+/**
+ * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file
+ * @inode: the inode to be searched
+ * @pgoff: the offset to be searched
+ * @pagep: the pointer for the found page to be stored
+ * @ent: the pointer for the found swap entry to be stored
+ *
+ * If a page is found, refcount of it is incremented. Callers should handle
+ * these refcount.
+ */
+void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
+ struct page **pagep, swp_entry_t *ent)
+{
+ swp_entry_t entry = { .val = 0 }, *ptr;
+ struct page *page = NULL;
+ struct shmem_inode_info *info = SHMEM_I(inode);
+
+ if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
+ goto out;
+
+ spin_lock(&info->lock);
+ ptr = shmem_swp_entry(info, pgoff, NULL);
+#ifdef CONFIG_SWAP
+ if (ptr && ptr->val) {
+ entry.val = ptr->val;
+ page = find_get_page(&swapper_space, entry.val);
+ } else
+#endif
+ page = find_get_page(inode->i_mapping, pgoff);
+ if (ptr)
+ shmem_swp_unmap(ptr);
+ spin_unlock(&info->lock);
+out:
+ *pagep = page;
+ *ent = entry;
+}
+#endif
+
#else /* !CONFIG_SHMEM */
/*
return 0;
}
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR
+/**
+ * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file
+ * @inode: the inode to be searched
+ * @pgoff: the offset to be searched
+ * @pagep: the pointer for the found page to be stored
+ * @ent: the pointer for the found swap entry to be stored
+ *
+ * If a page is found, refcount of it is incremented. Callers should handle
+ * these refcount.
+ */
+void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
+ struct page **pagep, swp_entry_t *ent)
+{
+ struct page *page = NULL;
+
+ if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
+ goto out;
+ page = find_get_page(inode->i_mapping, pgoff);
+out:
+ *pagep = page;
+ *ent = (swp_entry_t){ .val = 0 };
+}
+#endif
+
#define shmem_vm_ops generic_file_vm_ops
#define shmem_file_operations ramfs_file_operations
#define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
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