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       1                 :            : // SPDX-License-Identifier: GPL-2.0-only
       2                 :            : /*
       3                 :            :  * Linux VM pressure
       4                 :            :  *
       5                 :            :  * Copyright 2012 Linaro Ltd.
       6                 :            :  *                Anton Vorontsov <anton.vorontsov@linaro.org>
       7                 :            :  *
       8                 :            :  * Based on ideas from Andrew Morton, David Rientjes, KOSAKI Motohiro,
       9                 :            :  * Leonid Moiseichuk, Mel Gorman, Minchan Kim and Pekka Enberg.
      10                 :            :  */
      11                 :            : 
      12                 :            : #include <linux/cgroup.h>
      13                 :            : #include <linux/fs.h>
      14                 :            : #include <linux/log2.h>
      15                 :            : #include <linux/sched.h>
      16                 :            : #include <linux/mm.h>
      17                 :            : #include <linux/vmstat.h>
      18                 :            : #include <linux/eventfd.h>
      19                 :            : #include <linux/slab.h>
      20                 :            : #include <linux/swap.h>
      21                 :            : #include <linux/printk.h>
      22                 :            : #include <linux/vmpressure.h>
      23                 :            : 
      24                 :            : /*
      25                 :            :  * The window size (vmpressure_win) is the number of scanned pages before
      26                 :            :  * we try to analyze scanned/reclaimed ratio. So the window is used as a
      27                 :            :  * rate-limit tunable for the "low" level notification, and also for
      28                 :            :  * averaging the ratio for medium/critical levels. Using small window
      29                 :            :  * sizes can cause lot of false positives, but too big window size will
      30                 :            :  * delay the notifications.
      31                 :            :  *
      32                 :            :  * As the vmscan reclaimer logic works with chunks which are multiple of
      33                 :            :  * SWAP_CLUSTER_MAX, it makes sense to use it for the window size as well.
      34                 :            :  *
      35                 :            :  * TODO: Make the window size depend on machine size, as we do for vmstat
      36                 :            :  * thresholds. Currently we set it to 512 pages (2MB for 4KB pages).
      37                 :            :  */
      38                 :            : static const unsigned long vmpressure_win = SWAP_CLUSTER_MAX * 16;
      39                 :            : 
      40                 :            : /*
      41                 :            :  * These thresholds are used when we account memory pressure through
      42                 :            :  * scanned/reclaimed ratio. The current values were chosen empirically. In
      43                 :            :  * essence, they are percents: the higher the value, the more number
      44                 :            :  * unsuccessful reclaims there were.
      45                 :            :  */
      46                 :            : static const unsigned int vmpressure_level_med = 60;
      47                 :            : static const unsigned int vmpressure_level_critical = 95;
      48                 :            : 
      49                 :            : /*
      50                 :            :  * When there are too little pages left to scan, vmpressure() may miss the
      51                 :            :  * critical pressure as number of pages will be less than "window size".
      52                 :            :  * However, in that case the vmscan priority will raise fast as the
      53                 :            :  * reclaimer will try to scan LRUs more deeply.
      54                 :            :  *
      55                 :            :  * The vmscan logic considers these special priorities:
      56                 :            :  *
      57                 :            :  * prio == DEF_PRIORITY (12): reclaimer starts with that value
      58                 :            :  * prio <= DEF_PRIORITY - 2 : kswapd becomes somewhat overwhelmed
      59                 :            :  * prio == 0                : close to OOM, kernel scans every page in an lru
      60                 :            :  *
      61                 :            :  * Any value in this range is acceptable for this tunable (i.e. from 12 to
      62                 :            :  * 0). Current value for the vmpressure_level_critical_prio is chosen
      63                 :            :  * empirically, but the number, in essence, means that we consider
      64                 :            :  * critical level when scanning depth is ~10% of the lru size (vmscan
      65                 :            :  * scans 'lru_size >> prio' pages, so it is actually 12.5%, or one
      66                 :            :  * eights).
      67                 :            :  */
      68                 :            : static const unsigned int vmpressure_level_critical_prio = ilog2(100 / 10);
      69                 :            : 
      70                 :            : static struct vmpressure *work_to_vmpressure(struct work_struct *work)
      71                 :            : {
      72                 :          0 :         return container_of(work, struct vmpressure, work);
      73                 :            : }
      74                 :            : 
      75                 :          0 : static struct vmpressure *vmpressure_parent(struct vmpressure *vmpr)
      76                 :            : {
      77                 :          0 :         struct cgroup_subsys_state *css = vmpressure_to_css(vmpr);
      78                 :            :         struct mem_cgroup *memcg = mem_cgroup_from_css(css);
      79                 :            : 
      80                 :            :         memcg = parent_mem_cgroup(memcg);
      81                 :          0 :         if (!memcg)
      82                 :            :                 return NULL;
      83                 :          0 :         return memcg_to_vmpressure(memcg);
      84                 :            : }
      85                 :            : 
      86                 :            : enum vmpressure_levels {
      87                 :            :         VMPRESSURE_LOW = 0,
      88                 :            :         VMPRESSURE_MEDIUM,
      89                 :            :         VMPRESSURE_CRITICAL,
      90                 :            :         VMPRESSURE_NUM_LEVELS,
      91                 :            : };
      92                 :            : 
      93                 :            : enum vmpressure_modes {
      94                 :            :         VMPRESSURE_NO_PASSTHROUGH = 0,
      95                 :            :         VMPRESSURE_HIERARCHY,
      96                 :            :         VMPRESSURE_LOCAL,
      97                 :            :         VMPRESSURE_NUM_MODES,
      98                 :            : };
      99                 :            : 
     100                 :            : static const char * const vmpressure_str_levels[] = {
     101                 :            :         [VMPRESSURE_LOW] = "low",
     102                 :            :         [VMPRESSURE_MEDIUM] = "medium",
     103                 :            :         [VMPRESSURE_CRITICAL] = "critical",
     104                 :            : };
     105                 :            : 
     106                 :            : static const char * const vmpressure_str_modes[] = {
     107                 :            :         [VMPRESSURE_NO_PASSTHROUGH] = "default",
     108                 :            :         [VMPRESSURE_HIERARCHY] = "hierarchy",
     109                 :            :         [VMPRESSURE_LOCAL] = "local",
     110                 :            : };
     111                 :            : 
     112                 :            : static enum vmpressure_levels vmpressure_level(unsigned long pressure)
     113                 :            : {
     114                 :          0 :         if (pressure >= vmpressure_level_critical)
     115                 :            :                 return VMPRESSURE_CRITICAL;
     116                 :          0 :         else if (pressure >= vmpressure_level_med)
     117                 :            :                 return VMPRESSURE_MEDIUM;
     118                 :            :         return VMPRESSURE_LOW;
     119                 :            : }
     120                 :            : 
     121                 :            : static enum vmpressure_levels vmpressure_calc_level(unsigned long scanned,
     122                 :            :                                                     unsigned long reclaimed)
     123                 :            : {
     124                 :          0 :         unsigned long scale = scanned + reclaimed;
     125                 :            :         unsigned long pressure = 0;
     126                 :            : 
     127                 :            :         /*
     128                 :            :          * reclaimed can be greater than scanned for things such as reclaimed
     129                 :            :          * slab pages. shrink_node() just adds reclaimed pages without a
     130                 :            :          * related increment to scanned pages.
     131                 :            :          */
     132                 :          0 :         if (reclaimed >= scanned)
     133                 :            :                 goto out;
     134                 :            :         /*
     135                 :            :          * We calculate the ratio (in percents) of how many pages were
     136                 :            :          * scanned vs. reclaimed in a given time frame (window). Note that
     137                 :            :          * time is in VM reclaimer's "ticks", i.e. number of pages
     138                 :            :          * scanned. This makes it possible to set desired reaction time
     139                 :            :          * and serves as a ratelimit.
     140                 :            :          */
     141                 :          0 :         pressure = scale - (reclaimed * scale / scanned);
     142                 :          0 :         pressure = pressure * 100 / scale;
     143                 :            : 
     144                 :            : out:
     145                 :            :         pr_debug("%s: %3lu  (s: %lu  r: %lu)\n", __func__, pressure,
     146                 :            :                  scanned, reclaimed);
     147                 :            : 
     148                 :            :         return vmpressure_level(pressure);
     149                 :            : }
     150                 :            : 
     151                 :            : struct vmpressure_event {
     152                 :            :         struct eventfd_ctx *efd;
     153                 :            :         enum vmpressure_levels level;
     154                 :            :         enum vmpressure_modes mode;
     155                 :            :         struct list_head node;
     156                 :            : };
     157                 :            : 
     158                 :          0 : static bool vmpressure_event(struct vmpressure *vmpr,
     159                 :            :                              const enum vmpressure_levels level,
     160                 :            :                              bool ancestor, bool signalled)
     161                 :            : {
     162                 :            :         struct vmpressure_event *ev;
     163                 :            :         bool ret = false;
     164                 :            : 
     165                 :          0 :         mutex_lock(&vmpr->events_lock);
     166                 :          0 :         list_for_each_entry(ev, &vmpr->events, node) {
     167                 :          0 :                 if (ancestor && ev->mode == VMPRESSURE_LOCAL)
     168                 :          0 :                         continue;
     169                 :          0 :                 if (signalled && ev->mode == VMPRESSURE_NO_PASSTHROUGH)
     170                 :          0 :                         continue;
     171                 :          0 :                 if (level < ev->level)
     172                 :          0 :                         continue;
     173                 :          0 :                 eventfd_signal(ev->efd, 1);
     174                 :            :                 ret = true;
     175                 :            :         }
     176                 :          0 :         mutex_unlock(&vmpr->events_lock);
     177                 :            : 
     178                 :          0 :         return ret;
     179                 :            : }
     180                 :            : 
     181                 :          0 : static void vmpressure_work_fn(struct work_struct *work)
     182                 :            : {
     183                 :            :         struct vmpressure *vmpr = work_to_vmpressure(work);
     184                 :            :         unsigned long scanned;
     185                 :            :         unsigned long reclaimed;
     186                 :            :         enum vmpressure_levels level;
     187                 :            :         bool ancestor = false;
     188                 :            :         bool signalled = false;
     189                 :            : 
     190                 :            :         spin_lock(&vmpr->sr_lock);
     191                 :            :         /*
     192                 :            :          * Several contexts might be calling vmpressure(), so it is
     193                 :            :          * possible that the work was rescheduled again before the old
     194                 :            :          * work context cleared the counters. In that case we will run
     195                 :            :          * just after the old work returns, but then scanned might be zero
     196                 :            :          * here. No need for any locks here since we don't care if
     197                 :            :          * vmpr->reclaimed is in sync.
     198                 :            :          */
     199                 :          0 :         scanned = vmpr->tree_scanned;
     200                 :          0 :         if (!scanned) {
     201                 :            :                 spin_unlock(&vmpr->sr_lock);
     202                 :          0 :                 return;
     203                 :            :         }
     204                 :            : 
     205                 :          0 :         reclaimed = vmpr->tree_reclaimed;
     206                 :          0 :         vmpr->tree_scanned = 0;
     207                 :          0 :         vmpr->tree_reclaimed = 0;
     208                 :            :         spin_unlock(&vmpr->sr_lock);
     209                 :            : 
     210                 :            :         level = vmpressure_calc_level(scanned, reclaimed);
     211                 :            : 
     212                 :            :         do {
     213                 :          0 :                 if (vmpressure_event(vmpr, level, ancestor, signalled))
     214                 :            :                         signalled = true;
     215                 :            :                 ancestor = true;
     216                 :          0 :         } while ((vmpr = vmpressure_parent(vmpr)));
     217                 :            : }
     218                 :            : 
     219                 :            : /**
     220                 :            :  * vmpressure() - Account memory pressure through scanned/reclaimed ratio
     221                 :            :  * @gfp:        reclaimer's gfp mask
     222                 :            :  * @memcg:      cgroup memory controller handle
     223                 :            :  * @tree:       legacy subtree mode
     224                 :            :  * @scanned:    number of pages scanned
     225                 :            :  * @reclaimed:  number of pages reclaimed
     226                 :            :  *
     227                 :            :  * This function should be called from the vmscan reclaim path to account
     228                 :            :  * "instantaneous" memory pressure (scanned/reclaimed ratio). The raw
     229                 :            :  * pressure index is then further refined and averaged over time.
     230                 :            :  *
     231                 :            :  * If @tree is set, vmpressure is in traditional userspace reporting
     232                 :            :  * mode: @memcg is considered the pressure root and userspace is
     233                 :            :  * notified of the entire subtree's reclaim efficiency.
     234                 :            :  *
     235                 :            :  * If @tree is not set, reclaim efficiency is recorded for @memcg, and
     236                 :            :  * only in-kernel users are notified.
     237                 :            :  *
     238                 :            :  * This function does not return any value.
     239                 :            :  */
     240                 :          0 : void vmpressure(gfp_t gfp, struct mem_cgroup *memcg, bool tree,
     241                 :            :                 unsigned long scanned, unsigned long reclaimed)
     242                 :            : {
     243                 :          0 :         struct vmpressure *vmpr = memcg_to_vmpressure(memcg);
     244                 :            : 
     245                 :            :         /*
     246                 :            :          * Here we only want to account pressure that userland is able to
     247                 :            :          * help us with. For example, suppose that DMA zone is under
     248                 :            :          * pressure; if we notify userland about that kind of pressure,
     249                 :            :          * then it will be mostly a waste as it will trigger unnecessary
     250                 :            :          * freeing of memory by userland (since userland is more likely to
     251                 :            :          * have HIGHMEM/MOVABLE pages instead of the DMA fallback). That
     252                 :            :          * is why we include only movable, highmem and FS/IO pages.
     253                 :            :          * Indirect reclaim (kswapd) sets sc->gfp_mask to GFP_KERNEL, so
     254                 :            :          * we account it too.
     255                 :            :          */
     256                 :          0 :         if (!(gfp & (__GFP_HIGHMEM | __GFP_MOVABLE | __GFP_IO | __GFP_FS)))
     257                 :            :                 return;
     258                 :            : 
     259                 :            :         /*
     260                 :            :          * If we got here with no pages scanned, then that is an indicator
     261                 :            :          * that reclaimer was unable to find any shrinkable LRUs at the
     262                 :            :          * current scanning depth. But it does not mean that we should
     263                 :            :          * report the critical pressure, yet. If the scanning priority
     264                 :            :          * (scanning depth) goes too high (deep), we will be notified
     265                 :            :          * through vmpressure_prio(). But so far, keep calm.
     266                 :            :          */
     267                 :          0 :         if (!scanned)
     268                 :            :                 return;
     269                 :            : 
     270                 :          0 :         if (tree) {
     271                 :            :                 spin_lock(&vmpr->sr_lock);
     272                 :          0 :                 scanned = vmpr->tree_scanned += scanned;
     273                 :          0 :                 vmpr->tree_reclaimed += reclaimed;
     274                 :            :                 spin_unlock(&vmpr->sr_lock);
     275                 :            : 
     276                 :          0 :                 if (scanned < vmpressure_win)
     277                 :            :                         return;
     278                 :          0 :                 schedule_work(&vmpr->work);
     279                 :            :         } else {
     280                 :            :                 enum vmpressure_levels level;
     281                 :            : 
     282                 :            :                 /* For now, no users for root-level efficiency */
     283                 :          0 :                 if (!memcg || memcg == root_mem_cgroup)
     284                 :            :                         return;
     285                 :            : 
     286                 :            :                 spin_lock(&vmpr->sr_lock);
     287                 :          0 :                 scanned = vmpr->scanned += scanned;
     288                 :          0 :                 reclaimed = vmpr->reclaimed += reclaimed;
     289                 :          0 :                 if (scanned < vmpressure_win) {
     290                 :            :                         spin_unlock(&vmpr->sr_lock);
     291                 :            :                         return;
     292                 :            :                 }
     293                 :          0 :                 vmpr->scanned = vmpr->reclaimed = 0;
     294                 :            :                 spin_unlock(&vmpr->sr_lock);
     295                 :            : 
     296                 :            :                 level = vmpressure_calc_level(scanned, reclaimed);
     297                 :            : 
     298                 :          0 :                 if (level > VMPRESSURE_LOW) {
     299                 :            :                         /*
     300                 :            :                          * Let the socket buffer allocator know that
     301                 :            :                          * we are having trouble reclaiming LRU pages.
     302                 :            :                          *
     303                 :            :                          * For hysteresis keep the pressure state
     304                 :            :                          * asserted for a second in which subsequent
     305                 :            :                          * pressure events can occur.
     306                 :            :                          */
     307                 :          0 :                         memcg->socket_pressure = jiffies + HZ;
     308                 :            :                 }
     309                 :            :         }
     310                 :            : }
     311                 :            : 
     312                 :            : /**
     313                 :            :  * vmpressure_prio() - Account memory pressure through reclaimer priority level
     314                 :            :  * @gfp:        reclaimer's gfp mask
     315                 :            :  * @memcg:      cgroup memory controller handle
     316                 :            :  * @prio:       reclaimer's priority
     317                 :            :  *
     318                 :            :  * This function should be called from the reclaim path every time when
     319                 :            :  * the vmscan's reclaiming priority (scanning depth) changes.
     320                 :            :  *
     321                 :            :  * This function does not return any value.
     322                 :            :  */
     323                 :          0 : void vmpressure_prio(gfp_t gfp, struct mem_cgroup *memcg, int prio)
     324                 :            : {
     325                 :            :         /*
     326                 :            :          * We only use prio for accounting critical level. For more info
     327                 :            :          * see comment for vmpressure_level_critical_prio variable above.
     328                 :            :          */
     329                 :          0 :         if (prio > vmpressure_level_critical_prio)
     330                 :          0 :                 return;
     331                 :            : 
     332                 :            :         /*
     333                 :            :          * OK, the prio is below the threshold, updating vmpressure
     334                 :            :          * information before shrinker dives into long shrinking of long
     335                 :            :          * range vmscan. Passing scanned = vmpressure_win, reclaimed = 0
     336                 :            :          * to the vmpressure() basically means that we signal 'critical'
     337                 :            :          * level.
     338                 :            :          */
     339                 :          0 :         vmpressure(gfp, memcg, true, vmpressure_win, 0);
     340                 :            : }
     341                 :            : 
     342                 :            : #define MAX_VMPRESSURE_ARGS_LEN (strlen("critical") + strlen("hierarchy") + 2)
     343                 :            : 
     344                 :            : /**
     345                 :            :  * vmpressure_register_event() - Bind vmpressure notifications to an eventfd
     346                 :            :  * @memcg:      memcg that is interested in vmpressure notifications
     347                 :            :  * @eventfd:    eventfd context to link notifications with
     348                 :            :  * @args:       event arguments (pressure level threshold, optional mode)
     349                 :            :  *
     350                 :            :  * This function associates eventfd context with the vmpressure
     351                 :            :  * infrastructure, so that the notifications will be delivered to the
     352                 :            :  * @eventfd. The @args parameter is a comma-delimited string that denotes a
     353                 :            :  * pressure level threshold (one of vmpressure_str_levels, i.e. "low", "medium",
     354                 :            :  * or "critical") and an optional mode (one of vmpressure_str_modes, i.e.
     355                 :            :  * "hierarchy" or "local").
     356                 :            :  *
     357                 :            :  * To be used as memcg event method.
     358                 :            :  *
     359                 :            :  * Return: 0 on success, -ENOMEM on memory failure or -EINVAL if @args could
     360                 :            :  * not be parsed.
     361                 :            :  */
     362                 :          0 : int vmpressure_register_event(struct mem_cgroup *memcg,
     363                 :            :                               struct eventfd_ctx *eventfd, const char *args)
     364                 :            : {
     365                 :          0 :         struct vmpressure *vmpr = memcg_to_vmpressure(memcg);
     366                 :            :         struct vmpressure_event *ev;
     367                 :            :         enum vmpressure_modes mode = VMPRESSURE_NO_PASSTHROUGH;
     368                 :            :         enum vmpressure_levels level;
     369                 :            :         char *spec, *spec_orig;
     370                 :            :         char *token;
     371                 :            :         int ret = 0;
     372                 :            : 
     373                 :          0 :         spec_orig = spec = kstrndup(args, MAX_VMPRESSURE_ARGS_LEN, GFP_KERNEL);
     374                 :          0 :         if (!spec) {
     375                 :            :                 ret = -ENOMEM;
     376                 :            :                 goto out;
     377                 :            :         }
     378                 :            : 
     379                 :            :         /* Find required level */
     380                 :          0 :         token = strsep(&spec, ",");
     381                 :          0 :         ret = match_string(vmpressure_str_levels, VMPRESSURE_NUM_LEVELS, token);
     382                 :          0 :         if (ret < 0)
     383                 :            :                 goto out;
     384                 :          0 :         level = ret;
     385                 :            : 
     386                 :            :         /* Find optional mode */
     387                 :          0 :         token = strsep(&spec, ",");
     388                 :          0 :         if (token) {
     389                 :          0 :                 ret = match_string(vmpressure_str_modes, VMPRESSURE_NUM_MODES, token);
     390                 :          0 :                 if (ret < 0)
     391                 :            :                         goto out;
     392                 :          0 :                 mode = ret;
     393                 :            :         }
     394                 :            : 
     395                 :          0 :         ev = kzalloc(sizeof(*ev), GFP_KERNEL);
     396                 :          0 :         if (!ev) {
     397                 :            :                 ret = -ENOMEM;
     398                 :            :                 goto out;
     399                 :            :         }
     400                 :            : 
     401                 :          0 :         ev->efd = eventfd;
     402                 :          0 :         ev->level = level;
     403                 :          0 :         ev->mode = mode;
     404                 :            : 
     405                 :          0 :         mutex_lock(&vmpr->events_lock);
     406                 :          0 :         list_add(&ev->node, &vmpr->events);
     407                 :          0 :         mutex_unlock(&vmpr->events_lock);
     408                 :            :         ret = 0;
     409                 :            : out:
     410                 :          0 :         kfree(spec_orig);
     411                 :          0 :         return ret;
     412                 :            : }
     413                 :            : 
     414                 :            : /**
     415                 :            :  * vmpressure_unregister_event() - Unbind eventfd from vmpressure
     416                 :            :  * @memcg:      memcg handle
     417                 :            :  * @eventfd:    eventfd context that was used to link vmpressure with the @cg
     418                 :            :  *
     419                 :            :  * This function does internal manipulations to detach the @eventfd from
     420                 :            :  * the vmpressure notifications, and then frees internal resources
     421                 :            :  * associated with the @eventfd (but the @eventfd itself is not freed).
     422                 :            :  *
     423                 :            :  * To be used as memcg event method.
     424                 :            :  */
     425                 :          0 : void vmpressure_unregister_event(struct mem_cgroup *memcg,
     426                 :            :                                  struct eventfd_ctx *eventfd)
     427                 :            : {
     428                 :          0 :         struct vmpressure *vmpr = memcg_to_vmpressure(memcg);
     429                 :            :         struct vmpressure_event *ev;
     430                 :            : 
     431                 :          0 :         mutex_lock(&vmpr->events_lock);
     432                 :          0 :         list_for_each_entry(ev, &vmpr->events, node) {
     433                 :          0 :                 if (ev->efd != eventfd)
     434                 :          0 :                         continue;
     435                 :            :                 list_del(&ev->node);
     436                 :          0 :                 kfree(ev);
     437                 :          0 :                 break;
     438                 :            :         }
     439                 :          0 :         mutex_unlock(&vmpr->events_lock);
     440                 :          0 : }
     441                 :            : 
     442                 :            : /**
     443                 :            :  * vmpressure_init() - Initialize vmpressure control structure
     444                 :            :  * @vmpr:       Structure to be initialized
     445                 :            :  *
     446                 :            :  * This function should be called on every allocated vmpressure structure
     447                 :            :  * before any usage.
     448                 :            :  */
     449                 :          3 : void vmpressure_init(struct vmpressure *vmpr)
     450                 :            : {
     451                 :          3 :         spin_lock_init(&vmpr->sr_lock);
     452                 :          3 :         mutex_init(&vmpr->events_lock);
     453                 :          3 :         INIT_LIST_HEAD(&vmpr->events);
     454                 :          3 :         INIT_WORK(&vmpr->work, vmpressure_work_fn);
     455                 :          3 : }
     456                 :            : 
     457                 :            : /**
     458                 :            :  * vmpressure_cleanup() - shuts down vmpressure control structure
     459                 :            :  * @vmpr:       Structure to be cleaned up
     460                 :            :  *
     461                 :            :  * This function should be called before the structure in which it is
     462                 :            :  * embedded is cleaned up.
     463                 :            :  */
     464                 :          0 : void vmpressure_cleanup(struct vmpressure *vmpr)
     465                 :            : {
     466                 :            :         /*
     467                 :            :          * Make sure there is no pending work before eventfd infrastructure
     468                 :            :          * goes away.
     469                 :            :          */
     470                 :          0 :         flush_work(&vmpr->work);
     471                 :          0 : }