mm/vmscan.c: add a new member reclaim_state in struct shrink_control

Patch series "mm/vmscan: calculate reclaimed slab in all reclaim paths".

This patchset is to fix the issues in doing shrink slab.

There're six different reclaim paths by now,
 - kswapd reclaim path
 - node reclaim path
 - hibernate preallocate memory reclaim path
 - direct reclaim path
 - memcg reclaim path
 - memcg softlimit reclaim path

The slab caches reclaimed in these paths are only calculated in the
above three paths.  The issues are detailed explained in patch #2.  We
should calculate the reclaimed slab caches in every reclaim path.  In
order to do it, the struct reclaim_state is placed into the struct
shrink_control.

In node reclaim path, there'is another issue about shrinking slab, which
is adressed in "mm/vmscan: shrink slab in node reclaim"
(https://lore.kernel.org/linux-mm/1559874946-22960-1-git-send-email-laoar.shao@gmail.com/).

This patch (of 2):

The struct reclaim_state is used to record how many slab caches are
reclaimed in one reclaim path.  The struct shrink_control is used to
control one reclaim path.  So we'd better put reclaim_state into
shrink_control.

[laoar.shao@gmail.com: remove reclaim_state assignment from __perform_reclaim()]
Link: http://lkml.kernel.org/r/1561381582-13697-1-git-send-email-laoar.shao@gmail.com
Link: http://lkml.kernel.org/r/1561112086-6169-2-git-send-email-laoar.shao@gmail.com
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8fd7f45a04eb3958561b9fdaf392d71da0a2895f..e515bfcf7f288fbea352cbafc7daf4f0f2320ca3 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4102,7 +4102,6 @@ static int
 __perform_reclaim(gfp_t gfp_mask, unsigned int order,
                                        const struct alloc_context *ac)
 {
-       struct reclaim_state reclaim_state;
        int progress;
        unsigned int noreclaim_flag;
        unsigned long pflags;
@@ -4114,13 +4113,10 @@ __perform_reclaim(gfp_t gfp_mask, unsigned int order,
        psi_memstall_enter(&pflags);
        fs_reclaim_acquire(gfp_mask);
        noreclaim_flag = memalloc_noreclaim_save();
-       reclaim_state.reclaimed_slab = 0;
-       current->reclaim_state = &reclaim_state;
 
        progress = try_to_free_pages(ac->zonelist, order, gfp_mask,
                                                                ac->nodemask);
 
-       current->reclaim_state = NULL;
        memalloc_noreclaim_restore(noreclaim_flag);
        fs_reclaim_release(gfp_mask);
        psi_memstall_leave(&pflags);

diff --git a/mm/vmscan.c b/mm/vmscan.c
index f8e3dcd527b8a52637aee399050ba6e7d0d28b64..a01897fdfdac3bbfa28bafd50c07614907c0bb2d 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -131,6 +131,9 @@ struct scan_control {
                unsigned int file_taken;
                unsigned int taken;
        } nr;
+
+       /* for recording the reclaimed slab by now */
+       struct reclaim_state reclaim_state;
 };
 
 #ifdef ARCH_HAS_PREFETCH
@@ -3483,6 +3486,7 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
                .may_unmap = 1,
        };
 
+       current->reclaim_state = &sc.reclaim_state;
        psi_memstall_enter(&pflags);
        __fs_reclaim_acquire();
 
@@ -3664,6 +3668,8 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
        snapshot_refaults(NULL, pgdat);
        __fs_reclaim_release();
        psi_memstall_leave(&pflags);
+       current->reclaim_state = NULL;
+
        /*
         * Return the order kswapd stopped reclaiming at as
         * prepare_kswapd_sleep() takes it into account. If another caller
@@ -3787,15 +3793,10 @@ static int kswapd(void *p)
        unsigned int classzone_idx = MAX_NR_ZONES - 1;
        pg_data_t *pgdat = (pg_data_t*)p;
        struct task_struct *tsk = current;
-
-       struct reclaim_state reclaim_state = {
-               .reclaimed_slab = 0,
-       };
        const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
 
        if (!cpumask_empty(cpumask))
                set_cpus_allowed_ptr(tsk, cpumask);
-       current->reclaim_state = &reclaim_state;
 
        /*
         * Tell the memory management that we're a "memory allocator",
@@ -3857,7 +3858,6 @@ static int kswapd(void *p)
        }
 
        tsk->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD);
-       current->reclaim_state = NULL;
 
        return 0;
 }
@@ -3922,7 +3922,6 @@ void wakeup_kswapd(struct zone *zone, gfp_t gfp_flags, int order,
  */
 unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
 {
-       struct reclaim_state reclaim_state;
        struct scan_control sc = {
                .nr_to_reclaim = nr_to_reclaim,
                .gfp_mask = GFP_HIGHUSER_MOVABLE,
@@ -3940,8 +3939,7 @@ unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
 
        fs_reclaim_acquire(sc.gfp_mask);
        noreclaim_flag = memalloc_noreclaim_save();
-       reclaim_state.reclaimed_slab = 0;
-       p->reclaim_state = &reclaim_state;
+       p->reclaim_state = &sc.reclaim_state;
 
        nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
 
@@ -4110,7 +4108,6 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in
        /* Minimum pages needed in order to stay on node */
        const unsigned long nr_pages = 1 << order;
        struct task_struct *p = current;
-       struct reclaim_state reclaim_state;
        unsigned int noreclaim_flag;
        struct scan_control sc = {
                .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
@@ -4135,8 +4132,7 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in
         */
        noreclaim_flag = memalloc_noreclaim_save();
        p->flags |= PF_SWAPWRITE;
-       reclaim_state.reclaimed_slab = 0;
-       p->reclaim_state = &reclaim_state;
+       p->reclaim_state = &sc.reclaim_state;
 
        if (node_pagecache_reclaimable(pgdat) > pgdat->min_unmapped_pages) {
                /*