zram: extend writeback interface for pid
Extend writeback interface that operate on per pid where it tries to push the pages from ZRAM to backing device. usage: echo "pid=<pid no> limit=<bytes>" > /sys/block/zram0/writeback . Change-Id: I43cb5d4e0fc7838a7dfdf03c29ada3746545d481 Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com>
This commit is contained in:
Charan Teja Kalla
parent
68567e4574
commit
6adbd95c6d
@ -33,6 +33,9 @@
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#include <linux/debugfs.h>
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#include <linux/cpuhotplug.h>
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#include <linux/part_stat.h>
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#include <linux/mm_types.h>
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#include <linux/pgtable.h>
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#include <linux/hugetlb.h>
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#include "zram_drv.h"
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@ -628,11 +631,25 @@ static int read_from_bdev_async(struct zram *zram, struct bio_vec *bvec,
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}
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#define PAGE_WB_SIG "page_index="
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#define PID_WB_SIG "pid="
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#define LIMIT_WB_SIG "limit="
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#define PAGE_WRITEBACK 0
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#define HUGE_WRITEBACK (1<<0)
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#define IDLE_WRITEBACK (1<<1)
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#define PID_WRITEBACK (1<<15) /* Not much use of this as of today */
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struct zram_wb_store_walk {
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struct zram *zram;
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u64 limit; /* In page size of 4k */
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swp_entry_t *entries; /* for batch pte processing */
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struct mm_struct *mm;
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};
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#define INIT_ZRAM_WRITEBACK_STORE(name, zram) \
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struct zram_wb_store_walk name = { \
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.zram = zram, \
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}
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static ssize_t writeback_store_apply(struct zram *zram, unsigned long index,
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unsigned long nr_pages, int mode)
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@ -780,6 +797,197 @@ static ssize_t writeback_store_apply(struct zram *zram, unsigned long index,
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return ret;
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}
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static void walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
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struct zram_wb_store_walk *walk)
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{
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pte_t *pte;
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spinlock_t *ptl;
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swp_entry_t *entries = walk->entries;
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int i, index = 0;
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pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
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for (; addr < end; pte++, addr += PAGE_SIZE) {
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swp_entry_t entry;
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if (!walk->limit)
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break;
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if (pte_none(*pte))
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continue;
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if (is_swap_pte(*pte)) {
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entry = pte_to_swp_entry(*pte);
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if (is_pfn_swap_entry(entry))
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continue;
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entries[index++] = entry;
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--walk->limit;
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}
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}
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pte_unmap_unlock(pte, ptl);
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for (i = 0; i < index; ++i)
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writeback_store_apply(walk->zram, swp_offset(entries[i]), 1, PAGE_WRITEBACK);
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}
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static void walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
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struct zram_wb_store_walk *walk)
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{
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pmd_t *pmd;
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unsigned long next;
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pmd = pmd_offset(pud, addr);
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do {
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next = pmd_addr_end(addr, end);
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if (pmd_none(*pmd))
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continue;
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if (pmd_leaf(*pmd) || !pmd_present(*pmd))
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continue;
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if (pmd_trans_unstable(pmd))
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continue;
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if (is_hugepd(__hugepd(pmd_val(*pmd))))
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continue;
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walk_pte_range(pmd, addr, next, walk);
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} while (pmd++, addr = next, addr != end);
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}
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static void walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
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struct zram_wb_store_walk *walk)
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{
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pud_t *pud;
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unsigned long next;
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pud = pud_offset(p4d, addr);
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do {
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next = pud_addr_end(addr, end);
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if (pud_none(*pud))
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continue;
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if (pud_leaf(*pud) || !pud_present(*pud))
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continue;
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if (is_hugepd(__hugepd(pud_val(*pud))))
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continue;
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walk_pmd_range(pud, addr, next, walk);
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} while (pud++, addr = next, addr != end);
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}
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static void walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
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struct zram_wb_store_walk *walk)
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{
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p4d_t *p4d;
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unsigned long next;
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p4d = p4d_offset(pgd, addr);
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do {
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next = p4d_addr_end(addr, end);
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if (p4d_none_or_clear_bad(p4d))
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continue;
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if (is_hugepd(__hugepd(p4d_val(*p4d))))
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continue;
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walk_pud_range(p4d, addr, next, walk);
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} while (p4d++, addr = next, addr != end);
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}
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static void zram_wbstore(struct vm_area_struct *vma, struct zram_wb_store_walk *walk)
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{
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pgd_t *pgd;
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unsigned long start = vma->vm_start;
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unsigned long end = vma->vm_end;
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unsigned long next;
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mmap_assert_locked(walk->mm);// take read lock.
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pgd = pgd_offset(walk->mm, start);
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do {
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next = pgd_addr_end(start, end);
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if (pgd_none_or_clear_bad(pgd))
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continue;
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walk_p4d_range(pgd, start, next, walk);
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} while (pgd++, start = next, start != end);
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}
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static int parse_wb_store(const char *buf, size_t len,
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pid_t *pid, unsigned long *limit)
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{
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int ret;
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char *space;
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space = strnchr(buf, len, ' ');
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if (!space)
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return -EINVAL;
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*space = '\0';
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if (strncmp(buf, PID_WB_SIG, sizeof(PID_WB_SIG) - 1))
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return -EINVAL;
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buf += sizeof(PID_WB_SIG) - 1;
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ret = kstrtoint(buf, 10, pid);
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if (ret)
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return ret;
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while (*buf++ != '\0')
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;
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if (strncmp(buf, LIMIT_WB_SIG, sizeof(LIMIT_WB_SIG) - 1))
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return -EINVAL;
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buf += sizeof(LIMIT_WB_SIG) - 1;
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ret = kstrtoul(buf, 10, limit);
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if (ret)
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return ret;
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return 0;
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}
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static ssize_t writeback_pid_store(struct zram *zram, pid_t pid, unsigned long limit)
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{
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struct task_struct *task;
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struct mm_struct *mm;
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struct vm_area_struct *vma;
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struct vma_iterator vmi;
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int ret = 0;
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INIT_ZRAM_WRITEBACK_STORE(walk, zram);
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rcu_read_lock();
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task = find_task_by_vpid(pid);
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if (task)
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get_task_struct(task);
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rcu_read_unlock();
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if (!task)
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return -ESRCH;
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mm = get_task_mm(task);
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if (!mm) {
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ret = -EINVAL;
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goto put_task;
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}
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walk.entries = kmalloc(PTRS_PER_PTE * sizeof(swp_entry_t), GFP_KERNEL);
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if (!walk.entries) {
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ret = -ENOMEM;
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goto put_mm;
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}
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walk.mm = mm;
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walk.limit = limit >> PAGE_SHIFT;
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vma_iter_init(&vmi, mm, 0);
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mmap_read_lock(mm);
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for_each_vma(vmi, vma) {
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if (!walk.limit)
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break;
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if (!vma_is_anonymous(vma))
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continue;
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zram_wbstore(vma, &walk);
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}
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mmap_read_unlock(mm);
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kfree(walk.entries);
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put_mm:
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mmput(mm);
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put_task:
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put_task_struct(task);
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return ret;
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}
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static ssize_t writeback_store(struct device *dev,
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struct device_attribute *attr, const char *buf, size_t len)
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{
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@ -787,6 +995,8 @@ static ssize_t writeback_store(struct device *dev,
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unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
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unsigned long index = 0;
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ssize_t ret = len;
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pid_t pid;
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unsigned long limit;
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int mode;
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if (sysfs_streq(buf, "idle"))
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@ -796,17 +1006,22 @@ static ssize_t writeback_store(struct device *dev,
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else if (sysfs_streq(buf, "huge_idle"))
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mode = IDLE_WRITEBACK | HUGE_WRITEBACK;
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else {
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if (strncmp(buf, PAGE_WB_SIG, sizeof(PAGE_WB_SIG) - 1))
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return -EINVAL;
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if (!strncmp(buf, PAGE_WB_SIG, sizeof(PAGE_WB_SIG) - 1)) {
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if (kstrtol(buf + sizeof(PAGE_WB_SIG) - 1, 10, &index) ||
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index >= nr_pages)
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return -EINVAL;
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nr_pages = 1;
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mode = PAGE_WRITEBACK;
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} else if (!parse_wb_store(buf, len, &pid, &limit)) {
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mode = PID_WRITEBACK;
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} else
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return -EINVAL;
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}
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if (mode == PID_WRITEBACK)
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ret = writeback_pid_store(zram, pid, limit);
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else
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ret = writeback_store_apply(zram, index, nr_pages, mode);
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return ret ? : len;
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