From 503c358cf1925853195ee39ec437e51138bbb7df Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Thu, 12 Feb 2015 14:58:47 -0800 Subject: list_lru: introduce list_lru_shrink_{count,walk} Kmem accounting of memcg is unusable now, because it lacks slab shrinker support. That means when we hit the limit we will get ENOMEM w/o any chance to recover. What we should do then is to call shrink_slab, which would reclaim old inode/dentry caches from this cgroup. This is what this patch set is intended to do. Basically, it does two things. First, it introduces the notion of per-memcg slab shrinker. A shrinker that wants to reclaim objects per cgroup should mark itself as SHRINKER_MEMCG_AWARE. Then it will be passed the memory cgroup to scan from in shrink_control->memcg. For such shrinkers shrink_slab iterates over the whole cgroup subtree under the target cgroup and calls the shrinker for each kmem-active memory cgroup. Secondly, this patch set makes the list_lru structure per-memcg. It's done transparently to list_lru users - everything they have to do is to tell list_lru_init that they want memcg-aware list_lru. Then the list_lru will automatically distribute objects among per-memcg lists basing on which cgroup the object is accounted to. This way to make FS shrinkers (icache, dcache) memcg-aware we only need to make them use memcg-aware list_lru, and this is what this patch set does. As before, this patch set only enables per-memcg kmem reclaim when the pressure goes from memory.limit, not from memory.kmem.limit. Handling memory.kmem.limit is going to be tricky due to GFP_NOFS allocations, and it is still unclear whether we will have this knob in the unified hierarchy. This patch (of 9): NUMA aware slab shrinkers use the list_lru structure to distribute objects coming from different NUMA nodes to different lists. Whenever such a shrinker needs to count or scan objects from a particular node, it issues commands like this: count = list_lru_count_node(lru, sc->nid); freed = list_lru_walk_node(lru, sc->nid, isolate_func, isolate_arg, &sc->nr_to_scan); where sc is an instance of the shrink_control structure passed to it from vmscan. To simplify this, let's add special list_lru functions to be used by shrinkers, list_lru_shrink_count() and list_lru_shrink_walk(), which consolidate the nid and nr_to_scan arguments in the shrink_control structure. This will also allow us to avoid patching shrinkers that use list_lru when we make shrink_slab() per-memcg - all we will have to do is extend the shrink_control structure to include the target memcg and make list_lru_shrink_{count,walk} handle this appropriately. Signed-off-by: Vladimir Davydov Suggested-by: Dave Chinner Cc: Johannes Weiner Cc: Michal Hocko Cc: Greg Thelen Cc: Glauber Costa Cc: Alexander Viro Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/gfs2/quota.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'fs/gfs2') diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c index 3e193cb36996..c15d6b216d0b 100644 --- a/fs/gfs2/quota.c +++ b/fs/gfs2/quota.c @@ -171,8 +171,8 @@ static unsigned long gfs2_qd_shrink_scan(struct shrinker *shrink, if (!(sc->gfp_mask & __GFP_FS)) return SHRINK_STOP; - freed = list_lru_walk_node(&gfs2_qd_lru, sc->nid, gfs2_qd_isolate, - &dispose, &sc->nr_to_scan); + freed = list_lru_shrink_walk(&gfs2_qd_lru, sc, + gfs2_qd_isolate, &dispose); gfs2_qd_dispose(&dispose); @@ -182,7 +182,7 @@ static unsigned long gfs2_qd_shrink_scan(struct shrinker *shrink, static unsigned long gfs2_qd_shrink_count(struct shrinker *shrink, struct shrink_control *sc) { - return vfs_pressure_ratio(list_lru_count_node(&gfs2_qd_lru, sc->nid)); + return vfs_pressure_ratio(list_lru_shrink_count(&gfs2_qd_lru, sc)); } struct shrinker gfs2_qd_shrinker = { -- cgit v1.2.3 From 3f97b163207c67a3b35931494ad3db1de66356f0 Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Thu, 12 Feb 2015 14:59:35 -0800 Subject: list_lru: add helpers to isolate items Currently, the isolate callback passed to the list_lru_walk family of functions is supposed to just delete an item from the list upon returning LRU_REMOVED or LRU_REMOVED_RETRY, while nr_items counter is fixed by __list_lru_walk_one after the callback returns. Since the callback is allowed to drop the lock after removing an item (it has to return LRU_REMOVED_RETRY then), the nr_items can be less than the actual number of elements on the list even if we check them under the lock. This makes it difficult to move items from one list_lru_one to another, which is required for per-memcg list_lru reparenting - we can't just splice the lists, we have to move entries one by one. This patch therefore introduces helpers that must be used by callback functions to isolate items instead of raw list_del/list_move. These are list_lru_isolate and list_lru_isolate_move. They not only remove the entry from the list, but also fix the nr_items counter, making sure nr_items always reflects the actual number of elements on the list if checked under the appropriate lock. Signed-off-by: Vladimir Davydov Cc: Johannes Weiner Cc: Michal Hocko Cc: Tejun Heo Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Dave Chinner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/dcache.c | 21 +++++++++++---------- fs/gfs2/quota.c | 5 +++-- fs/inode.c | 8 ++++---- fs/xfs/xfs_buf.c | 6 ++++-- fs/xfs/xfs_qm.c | 5 +++-- include/linux/list_lru.h | 9 +++++++-- mm/list_lru.c | 19 ++++++++++++++++--- mm/workingset.c | 3 ++- 8 files changed, 50 insertions(+), 26 deletions(-) (limited to 'fs/gfs2') diff --git a/fs/dcache.c b/fs/dcache.c index 56c5da89f58a..d04be762b216 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -400,19 +400,20 @@ static void d_shrink_add(struct dentry *dentry, struct list_head *list) * LRU lists entirely, while shrink_move moves it to the indicated * private list. */ -static void d_lru_isolate(struct dentry *dentry) +static void d_lru_isolate(struct list_lru_one *lru, struct dentry *dentry) { D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); dentry->d_flags &= ~DCACHE_LRU_LIST; this_cpu_dec(nr_dentry_unused); - list_del_init(&dentry->d_lru); + list_lru_isolate(lru, &dentry->d_lru); } -static void d_lru_shrink_move(struct dentry *dentry, struct list_head *list) +static void d_lru_shrink_move(struct list_lru_one *lru, struct dentry *dentry, + struct list_head *list) { D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); dentry->d_flags |= DCACHE_SHRINK_LIST; - list_move_tail(&dentry->d_lru, list); + list_lru_isolate_move(lru, &dentry->d_lru, list); } /* @@ -869,8 +870,8 @@ static void shrink_dentry_list(struct list_head *list) } } -static enum lru_status -dentry_lru_isolate(struct list_head *item, spinlock_t *lru_lock, void *arg) +static enum lru_status dentry_lru_isolate(struct list_head *item, + struct list_lru_one *lru, spinlock_t *lru_lock, void *arg) { struct list_head *freeable = arg; struct dentry *dentry = container_of(item, struct dentry, d_lru); @@ -890,7 +891,7 @@ dentry_lru_isolate(struct list_head *item, spinlock_t *lru_lock, void *arg) * another pass through the LRU. */ if (dentry->d_lockref.count) { - d_lru_isolate(dentry); + d_lru_isolate(lru, dentry); spin_unlock(&dentry->d_lock); return LRU_REMOVED; } @@ -921,7 +922,7 @@ dentry_lru_isolate(struct list_head *item, spinlock_t *lru_lock, void *arg) return LRU_ROTATE; } - d_lru_shrink_move(dentry, freeable); + d_lru_shrink_move(lru, dentry, freeable); spin_unlock(&dentry->d_lock); return LRU_REMOVED; @@ -951,7 +952,7 @@ long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc) } static enum lru_status dentry_lru_isolate_shrink(struct list_head *item, - spinlock_t *lru_lock, void *arg) + struct list_lru_one *lru, spinlock_t *lru_lock, void *arg) { struct list_head *freeable = arg; struct dentry *dentry = container_of(item, struct dentry, d_lru); @@ -964,7 +965,7 @@ static enum lru_status dentry_lru_isolate_shrink(struct list_head *item, if (!spin_trylock(&dentry->d_lock)) return LRU_SKIP; - d_lru_shrink_move(dentry, freeable); + d_lru_shrink_move(lru, dentry, freeable); spin_unlock(&dentry->d_lock); return LRU_REMOVED; diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c index c15d6b216d0b..3aa17d4d1cfc 100644 --- a/fs/gfs2/quota.c +++ b/fs/gfs2/quota.c @@ -145,7 +145,8 @@ static void gfs2_qd_dispose(struct list_head *list) } -static enum lru_status gfs2_qd_isolate(struct list_head *item, spinlock_t *lock, void *arg) +static enum lru_status gfs2_qd_isolate(struct list_head *item, + struct list_lru_one *lru, spinlock_t *lru_lock, void *arg) { struct list_head *dispose = arg; struct gfs2_quota_data *qd = list_entry(item, struct gfs2_quota_data, qd_lru); @@ -155,7 +156,7 @@ static enum lru_status gfs2_qd_isolate(struct list_head *item, spinlock_t *lock, if (qd->qd_lockref.count == 0) { lockref_mark_dead(&qd->qd_lockref); - list_move(&qd->qd_lru, dispose); + list_lru_isolate_move(lru, &qd->qd_lru, dispose); } spin_unlock(&qd->qd_lockref.lock); diff --git a/fs/inode.c b/fs/inode.c index 524a32c2b0c6..86c612b92c6f 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -685,8 +685,8 @@ int invalidate_inodes(struct super_block *sb, bool kill_dirty) * LRU does not have strict ordering. Hence we don't want to reclaim inodes * with this flag set because they are the inodes that are out of order. */ -static enum lru_status -inode_lru_isolate(struct list_head *item, spinlock_t *lru_lock, void *arg) +static enum lru_status inode_lru_isolate(struct list_head *item, + struct list_lru_one *lru, spinlock_t *lru_lock, void *arg) { struct list_head *freeable = arg; struct inode *inode = container_of(item, struct inode, i_lru); @@ -704,7 +704,7 @@ inode_lru_isolate(struct list_head *item, spinlock_t *lru_lock, void *arg) */ if (atomic_read(&inode->i_count) || (inode->i_state & ~I_REFERENCED)) { - list_del_init(&inode->i_lru); + list_lru_isolate(lru, &inode->i_lru); spin_unlock(&inode->i_lock); this_cpu_dec(nr_unused); return LRU_REMOVED; @@ -738,7 +738,7 @@ inode_lru_isolate(struct list_head *item, spinlock_t *lru_lock, void *arg) WARN_ON(inode->i_state & I_NEW); inode->i_state |= I_FREEING; - list_move(&inode->i_lru, freeable); + list_lru_isolate_move(lru, &inode->i_lru, freeable); spin_unlock(&inode->i_lock); this_cpu_dec(nr_unused); diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index 15c9d224c721..1790b00bea7a 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -1488,6 +1488,7 @@ xfs_buf_iomove( static enum lru_status xfs_buftarg_wait_rele( struct list_head *item, + struct list_lru_one *lru, spinlock_t *lru_lock, void *arg) @@ -1509,7 +1510,7 @@ xfs_buftarg_wait_rele( */ atomic_set(&bp->b_lru_ref, 0); bp->b_state |= XFS_BSTATE_DISPOSE; - list_move(item, dispose); + list_lru_isolate_move(lru, item, dispose); spin_unlock(&bp->b_lock); return LRU_REMOVED; } @@ -1546,6 +1547,7 @@ xfs_wait_buftarg( static enum lru_status xfs_buftarg_isolate( struct list_head *item, + struct list_lru_one *lru, spinlock_t *lru_lock, void *arg) { @@ -1569,7 +1571,7 @@ xfs_buftarg_isolate( } bp->b_state |= XFS_BSTATE_DISPOSE; - list_move(item, dispose); + list_lru_isolate_move(lru, item, dispose); spin_unlock(&bp->b_lock); return LRU_REMOVED; } diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c index 4f4b1274e144..53cc2aaf8d2b 100644 --- a/fs/xfs/xfs_qm.c +++ b/fs/xfs/xfs_qm.c @@ -430,6 +430,7 @@ struct xfs_qm_isolate { static enum lru_status xfs_qm_dquot_isolate( struct list_head *item, + struct list_lru_one *lru, spinlock_t *lru_lock, void *arg) __releases(lru_lock) __acquires(lru_lock) @@ -450,7 +451,7 @@ xfs_qm_dquot_isolate( XFS_STATS_INC(xs_qm_dqwants); trace_xfs_dqreclaim_want(dqp); - list_del_init(&dqp->q_lru); + list_lru_isolate(lru, &dqp->q_lru); XFS_STATS_DEC(xs_qm_dquot_unused); return LRU_REMOVED; } @@ -494,7 +495,7 @@ xfs_qm_dquot_isolate( xfs_dqunlock(dqp); ASSERT(dqp->q_nrefs == 0); - list_move_tail(&dqp->q_lru, &isol->dispose); + list_lru_isolate_move(lru, &dqp->q_lru, &isol->dispose); XFS_STATS_DEC(xs_qm_dquot_unused); trace_xfs_dqreclaim_done(dqp); XFS_STATS_INC(xs_qm_dqreclaims); diff --git a/include/linux/list_lru.h b/include/linux/list_lru.h index 305b598abac2..7edf9c9ab9eb 100644 --- a/include/linux/list_lru.h +++ b/include/linux/list_lru.h @@ -125,8 +125,13 @@ static inline unsigned long list_lru_count(struct list_lru *lru) return count; } -typedef enum lru_status -(*list_lru_walk_cb)(struct list_head *item, spinlock_t *lock, void *cb_arg); +void list_lru_isolate(struct list_lru_one *list, struct list_head *item); +void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item, + struct list_head *head); + +typedef enum lru_status (*list_lru_walk_cb)(struct list_head *item, + struct list_lru_one *list, spinlock_t *lock, void *cb_arg); + /** * list_lru_walk_one: walk a list_lru, isolating and disposing freeable items. * @lru: the lru pointer. diff --git a/mm/list_lru.c b/mm/list_lru.c index 79aee70c3b9d..8d9d168c6c38 100644 --- a/mm/list_lru.c +++ b/mm/list_lru.c @@ -132,6 +132,21 @@ bool list_lru_del(struct list_lru *lru, struct list_head *item) } EXPORT_SYMBOL_GPL(list_lru_del); +void list_lru_isolate(struct list_lru_one *list, struct list_head *item) +{ + list_del_init(item); + list->nr_items--; +} +EXPORT_SYMBOL_GPL(list_lru_isolate); + +void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item, + struct list_head *head) +{ + list_move(item, head); + list->nr_items--; +} +EXPORT_SYMBOL_GPL(list_lru_isolate_move); + static unsigned long __list_lru_count_one(struct list_lru *lru, int nid, int memcg_idx) { @@ -194,13 +209,11 @@ restart: break; --*nr_to_walk; - ret = isolate(item, &nlru->lock, cb_arg); + ret = isolate(item, l, &nlru->lock, cb_arg); switch (ret) { case LRU_REMOVED_RETRY: assert_spin_locked(&nlru->lock); case LRU_REMOVED: - l->nr_items--; - WARN_ON_ONCE(l->nr_items < 0); isolated++; /* * If the lru lock has been dropped, our list diff --git a/mm/workingset.c b/mm/workingset.c index d4fa7fb10a52..aa017133744b 100644 --- a/mm/workingset.c +++ b/mm/workingset.c @@ -302,6 +302,7 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker, } static enum lru_status shadow_lru_isolate(struct list_head *item, + struct list_lru_one *lru, spinlock_t *lru_lock, void *arg) { @@ -332,7 +333,7 @@ static enum lru_status shadow_lru_isolate(struct list_head *item, goto out; } - list_del_init(item); + list_lru_isolate(lru, item); spin_unlock(lru_lock); /* -- cgit v1.2.3