From 5035ebc644aec92d55d1bbfe042f35341e4bffb5 Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Tue, 31 May 2022 20:22:23 -0700 Subject: mm: shrinkers: introduce debugfs interface for memory shrinkers This commit introduces the /sys/kernel/debug/shrinker debugfs interface which provides an ability to observe the state of individual kernel memory shrinkers. Because the feature adds some memory overhead (which shouldn't be large unless there is a huge amount of registered shrinkers), it's guarded by a config option (enabled by default). This commit introduces the "count" interface for each shrinker registered in the system. The output is in the following format: ... ... ... To reduce the size of output on machines with many thousands cgroups, if the total number of objects on all nodes is 0, the line is omitted. If the shrinker is not memcg-aware or CONFIG_MEMCG is off, 0 is printed as cgroup inode id. If the shrinker is not numa-aware, 0's are printed for all nodes except the first one. This commit gives debugfs entries simple numeric names, which are not very convenient. The following commit in the series will provide shrinkers with more meaningful names. [akpm@linux-foundation.org: remove WARN_ON_ONCE(), per Roman] Reported-by: syzbot+300d27c79fe6d4cbcc39@syzkaller.appspotmail.com Link: https://lkml.kernel.org/r/20220601032227.4076670-3-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin Reviewed-by: Kent Overstreet Acked-by: Muchun Song Cc: Christophe JAILLET Cc: Dave Chinner Cc: Hillf Danton Signed-off-by: Andrew Morton --- mm/shrinker_debug.c | 168 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 168 insertions(+) create mode 100644 mm/shrinker_debug.c (limited to 'mm/shrinker_debug.c') diff --git a/mm/shrinker_debug.c b/mm/shrinker_debug.c new file mode 100644 index 000000000000..1a70556bd46c --- /dev/null +++ b/mm/shrinker_debug.c @@ -0,0 +1,168 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include + +/* defined in vmscan.c */ +extern struct rw_semaphore shrinker_rwsem; +extern struct list_head shrinker_list; + +static DEFINE_IDA(shrinker_debugfs_ida); +static struct dentry *shrinker_debugfs_root; + +static unsigned long shrinker_count_objects(struct shrinker *shrinker, + struct mem_cgroup *memcg, + unsigned long *count_per_node) +{ + unsigned long nr, total = 0; + int nid; + + for_each_node(nid) { + if (nid == 0 || (shrinker->flags & SHRINKER_NUMA_AWARE)) { + struct shrink_control sc = { + .gfp_mask = GFP_KERNEL, + .nid = nid, + .memcg = memcg, + }; + + nr = shrinker->count_objects(shrinker, &sc); + if (nr == SHRINK_EMPTY) + nr = 0; + } else { + nr = 0; + } + + count_per_node[nid] = nr; + total += nr; + } + + return total; +} + +static int shrinker_debugfs_count_show(struct seq_file *m, void *v) +{ + struct shrinker *shrinker = m->private; + unsigned long *count_per_node; + struct mem_cgroup *memcg; + unsigned long total; + bool memcg_aware; + int ret, nid; + + count_per_node = kcalloc(nr_node_ids, sizeof(unsigned long), GFP_KERNEL); + if (!count_per_node) + return -ENOMEM; + + ret = down_read_killable(&shrinker_rwsem); + if (ret) { + kfree(count_per_node); + return ret; + } + rcu_read_lock(); + + memcg_aware = shrinker->flags & SHRINKER_MEMCG_AWARE; + + memcg = mem_cgroup_iter(NULL, NULL, NULL); + do { + if (memcg && !mem_cgroup_online(memcg)) + continue; + + total = shrinker_count_objects(shrinker, + memcg_aware ? memcg : NULL, + count_per_node); + if (total) { + seq_printf(m, "%lu", mem_cgroup_ino(memcg)); + for_each_node(nid) + seq_printf(m, " %lu", count_per_node[nid]); + seq_putc(m, '\n'); + } + + if (!memcg_aware) { + mem_cgroup_iter_break(NULL, memcg); + break; + } + + if (signal_pending(current)) { + mem_cgroup_iter_break(NULL, memcg); + ret = -EINTR; + break; + } + } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL); + + rcu_read_unlock(); + up_read(&shrinker_rwsem); + + kfree(count_per_node); + return ret; +} +DEFINE_SHOW_ATTRIBUTE(shrinker_debugfs_count); + +int shrinker_debugfs_add(struct shrinker *shrinker) +{ + struct dentry *entry; + char buf[16]; + int id; + + lockdep_assert_held(&shrinker_rwsem); + + /* debugfs isn't initialized yet, add debugfs entries later. */ + if (!shrinker_debugfs_root) + return 0; + + id = ida_alloc(&shrinker_debugfs_ida, GFP_KERNEL); + if (id < 0) + return id; + shrinker->debugfs_id = id; + + snprintf(buf, sizeof(buf), "%d", id); + + /* create debugfs entry */ + entry = debugfs_create_dir(buf, shrinker_debugfs_root); + if (IS_ERR(entry)) { + ida_free(&shrinker_debugfs_ida, id); + return PTR_ERR(entry); + } + shrinker->debugfs_entry = entry; + + debugfs_create_file("count", 0220, entry, shrinker, + &shrinker_debugfs_count_fops); + return 0; +} + +void shrinker_debugfs_remove(struct shrinker *shrinker) +{ + lockdep_assert_held(&shrinker_rwsem); + + if (!shrinker->debugfs_entry) + return; + + debugfs_remove_recursive(shrinker->debugfs_entry); + ida_free(&shrinker_debugfs_ida, shrinker->debugfs_id); +} + +static int __init shrinker_debugfs_init(void) +{ + struct shrinker *shrinker; + struct dentry *dentry; + int ret = 0; + + dentry = debugfs_create_dir("shrinker", NULL); + if (IS_ERR(dentry)) + return PTR_ERR(dentry); + shrinker_debugfs_root = dentry; + + /* Create debugfs entries for shrinkers registered at boot */ + down_write(&shrinker_rwsem); + list_for_each_entry(shrinker, &shrinker_list, list) + if (!shrinker->debugfs_entry) { + ret = shrinker_debugfs_add(shrinker); + if (ret) + break; + } + up_write(&shrinker_rwsem); + + return ret; +} +late_initcall(shrinker_debugfs_init); -- cgit v1.2.3 From e33c267ab70de4249d22d7eab1cc7d68a889bac2 Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Tue, 31 May 2022 20:22:24 -0700 Subject: mm: shrinkers: provide shrinkers with names Currently shrinkers are anonymous objects. For debugging purposes they can be identified by count/scan function names, but it's not always useful: e.g. for superblock's shrinkers it's nice to have at least an idea of to which superblock the shrinker belongs. This commit adds names to shrinkers. register_shrinker() and prealloc_shrinker() functions are extended to take a format and arguments to master a name. In some cases it's not possible to determine a good name at the time when a shrinker is allocated. For such cases shrinker_debugfs_rename() is provided. The expected format is: -[:]- For some shrinkers an instance can be encoded as (MAJOR:MINOR) pair. After this change the shrinker debugfs directory looks like: $ cd /sys/kernel/debug/shrinker/ $ ls dquota-cache-16 sb-devpts-28 sb-proc-47 sb-tmpfs-42 mm-shadow-18 sb-devtmpfs-5 sb-proc-48 sb-tmpfs-43 mm-zspool:zram0-34 sb-hugetlbfs-17 sb-pstore-31 sb-tmpfs-44 rcu-kfree-0 sb-hugetlbfs-33 sb-rootfs-2 sb-tmpfs-49 sb-aio-20 sb-iomem-12 sb-securityfs-6 sb-tracefs-13 sb-anon_inodefs-15 sb-mqueue-21 sb-selinuxfs-22 sb-xfs:vda1-36 sb-bdev-3 sb-nsfs-4 sb-sockfs-8 sb-zsmalloc-19 sb-bpf-32 sb-pipefs-14 sb-sysfs-26 thp-deferred_split-10 sb-btrfs:vda2-24 sb-proc-25 sb-tmpfs-1 thp-zero-9 sb-cgroup2-30 sb-proc-39 sb-tmpfs-27 xfs-buf:vda1-37 sb-configfs-23 sb-proc-41 sb-tmpfs-29 xfs-inodegc:vda1-38 sb-dax-11 sb-proc-45 sb-tmpfs-35 sb-debugfs-7 sb-proc-46 sb-tmpfs-40 [roman.gushchin@linux.dev: fix build warnings] Link: https://lkml.kernel.org/r/Yr+ZTnLb9lJk6fJO@castle Reported-by: kernel test robot Link: https://lkml.kernel.org/r/20220601032227.4076670-4-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin Cc: Christophe JAILLET Cc: Dave Chinner Cc: Hillf Danton Cc: Kent Overstreet Cc: Muchun Song Signed-off-by: Andrew Morton --- arch/x86/kvm/mmu/mmu.c | 2 +- drivers/android/binder_alloc.c | 2 +- drivers/gpu/drm/i915/gem/i915_gem_shrinker.c | 3 +- drivers/gpu/drm/msm/msm_gem_shrinker.c | 2 +- drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c | 2 +- drivers/gpu/drm/ttm/ttm_pool.c | 2 +- drivers/md/bcache/btree.c | 2 +- drivers/md/dm-bufio.c | 3 +- drivers/md/dm-zoned-metadata.c | 4 +- drivers/md/raid5.c | 2 +- drivers/misc/vmw_balloon.c | 2 +- drivers/virtio/virtio_balloon.c | 2 +- drivers/xen/xenbus/xenbus_probe_backend.c | 2 +- fs/btrfs/super.c | 2 + fs/erofs/utils.c | 2 +- fs/ext4/extents_status.c | 3 +- fs/f2fs/super.c | 2 +- fs/gfs2/glock.c | 2 +- fs/gfs2/main.c | 2 +- fs/jbd2/journal.c | 3 +- fs/mbcache.c | 2 +- fs/nfs/nfs42xattr.c | 7 +-- fs/nfs/super.c | 2 +- fs/nfsd/filecache.c | 2 +- fs/nfsd/nfscache.c | 3 +- fs/quota/dquot.c | 2 +- fs/super.c | 6 ++- fs/ubifs/super.c | 2 +- fs/xfs/xfs_buf.c | 3 +- fs/xfs/xfs_icache.c | 2 +- fs/xfs/xfs_qm.c | 3 +- include/linux/shrinker.h | 14 +++++- kernel/rcu/tree.c | 2 +- mm/huge_memory.c | 4 +- mm/shrinker_debug.c | 47 ++++++++++++++++++- mm/vmscan.c | 58 ++++++++++++++++++++++-- mm/workingset.c | 2 +- mm/zsmalloc.c | 3 +- net/sunrpc/auth.c | 2 +- 39 files changed, 167 insertions(+), 45 deletions(-) (limited to 'mm/shrinker_debug.c') diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 17252f39bd7c..797d3286ecc1 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -6317,7 +6317,7 @@ int kvm_mmu_vendor_module_init(void) if (percpu_counter_init(&kvm_total_used_mmu_pages, 0, GFP_KERNEL)) goto out; - ret = register_shrinker(&mmu_shrinker); + ret = register_shrinker(&mmu_shrinker, "x86-mmu"); if (ret) goto out; diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c index 5649a0371a1f..51b502217d00 100644 --- a/drivers/android/binder_alloc.c +++ b/drivers/android/binder_alloc.c @@ -1084,7 +1084,7 @@ int binder_alloc_shrinker_init(void) int ret = list_lru_init(&binder_alloc_lru); if (ret == 0) { - ret = register_shrinker(&binder_shrinker); + ret = register_shrinker(&binder_shrinker, "android-binder"); if (ret) list_lru_destroy(&binder_alloc_lru); } diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c b/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c index 6a6ff98a8746..e43577e03067 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c @@ -426,7 +426,8 @@ void i915_gem_driver_register__shrinker(struct drm_i915_private *i915) i915->mm.shrinker.count_objects = i915_gem_shrinker_count; i915->mm.shrinker.seeks = DEFAULT_SEEKS; i915->mm.shrinker.batch = 4096; - drm_WARN_ON(&i915->drm, register_shrinker(&i915->mm.shrinker)); + drm_WARN_ON(&i915->drm, register_shrinker(&i915->mm.shrinker, + "drm-i915_gem")); i915->mm.oom_notifier.notifier_call = i915_gem_shrinker_oom; drm_WARN_ON(&i915->drm, register_oom_notifier(&i915->mm.oom_notifier)); diff --git a/drivers/gpu/drm/msm/msm_gem_shrinker.c b/drivers/gpu/drm/msm/msm_gem_shrinker.c index 086dacf2f26a..26e84d2ea6ae 100644 --- a/drivers/gpu/drm/msm/msm_gem_shrinker.c +++ b/drivers/gpu/drm/msm/msm_gem_shrinker.c @@ -221,7 +221,7 @@ void msm_gem_shrinker_init(struct drm_device *dev) priv->shrinker.count_objects = msm_gem_shrinker_count; priv->shrinker.scan_objects = msm_gem_shrinker_scan; priv->shrinker.seeks = DEFAULT_SEEKS; - WARN_ON(register_shrinker(&priv->shrinker)); + WARN_ON(register_shrinker(&priv->shrinker, "drm-msm_gem")); priv->vmap_notifier.notifier_call = msm_gem_shrinker_vmap; WARN_ON(register_vmap_purge_notifier(&priv->vmap_notifier)); diff --git a/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c b/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c index 77e7cb6d1ae3..bf0170782f25 100644 --- a/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c +++ b/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c @@ -103,7 +103,7 @@ void panfrost_gem_shrinker_init(struct drm_device *dev) pfdev->shrinker.count_objects = panfrost_gem_shrinker_count; pfdev->shrinker.scan_objects = panfrost_gem_shrinker_scan; pfdev->shrinker.seeks = DEFAULT_SEEKS; - WARN_ON(register_shrinker(&pfdev->shrinker)); + WARN_ON(register_shrinker(&pfdev->shrinker, "drm-panfrost")); } /** diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c index 1bba0a0ed3f9..21b61631f73a 100644 --- a/drivers/gpu/drm/ttm/ttm_pool.c +++ b/drivers/gpu/drm/ttm/ttm_pool.c @@ -722,7 +722,7 @@ int ttm_pool_mgr_init(unsigned long num_pages) mm_shrinker.count_objects = ttm_pool_shrinker_count; mm_shrinker.scan_objects = ttm_pool_shrinker_scan; mm_shrinker.seeks = 1; - return register_shrinker(&mm_shrinker); + return register_shrinker(&mm_shrinker, "drm-ttm_pool"); } /** diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c index e136d6edc1ed..147c493a989a 100644 --- a/drivers/md/bcache/btree.c +++ b/drivers/md/bcache/btree.c @@ -812,7 +812,7 @@ int bch_btree_cache_alloc(struct cache_set *c) c->shrink.seeks = 4; c->shrink.batch = c->btree_pages * 2; - if (register_shrinker(&c->shrink)) + if (register_shrinker(&c->shrink, "md-bcache:%pU", c->set_uuid)) pr_warn("bcache: %s: could not register shrinker\n", __func__); diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c index 5ffa1dcf84cf..3ff571b20f14 100644 --- a/drivers/md/dm-bufio.c +++ b/drivers/md/dm-bufio.c @@ -1806,7 +1806,8 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign c->shrinker.scan_objects = dm_bufio_shrink_scan; c->shrinker.seeks = 1; c->shrinker.batch = 0; - r = register_shrinker(&c->shrinker); + r = register_shrinker(&c->shrinker, "md-%s:(%u:%u)", slab_name, + MAJOR(bdev->bd_dev), MINOR(bdev->bd_dev)); if (r) goto bad; diff --git a/drivers/md/dm-zoned-metadata.c b/drivers/md/dm-zoned-metadata.c index d1ea66114d14..46648f6100fb 100644 --- a/drivers/md/dm-zoned-metadata.c +++ b/drivers/md/dm-zoned-metadata.c @@ -2944,7 +2944,9 @@ int dmz_ctr_metadata(struct dmz_dev *dev, int num_dev, zmd->mblk_shrinker.seeks = DEFAULT_SEEKS; /* Metadata cache shrinker */ - ret = register_shrinker(&zmd->mblk_shrinker); + ret = register_shrinker(&zmd->mblk_shrinker, "md-meta:(%u:%u)", + MAJOR(dev->bdev->bd_dev), + MINOR(dev->bdev->bd_dev)); if (ret) { dmz_zmd_err(zmd, "Register metadata cache shrinker failed"); goto err; diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 5d09256d7f81..780ae66840b7 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -7414,7 +7414,7 @@ static struct r5conf *setup_conf(struct mddev *mddev) conf->shrinker.count_objects = raid5_cache_count; conf->shrinker.batch = 128; conf->shrinker.flags = 0; - ret = register_shrinker(&conf->shrinker); + ret = register_shrinker(&conf->shrinker, "md-raid5:%s", mdname(mddev)); if (ret) { pr_warn("md/raid:%s: couldn't register shrinker.\n", mdname(mddev)); diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c index 086ce77d9074..c2d2fa114e65 100644 --- a/drivers/misc/vmw_balloon.c +++ b/drivers/misc/vmw_balloon.c @@ -1587,7 +1587,7 @@ static int vmballoon_register_shrinker(struct vmballoon *b) b->shrinker.count_objects = vmballoon_shrinker_count; b->shrinker.seeks = DEFAULT_SEEKS; - r = register_shrinker(&b->shrinker); + r = register_shrinker(&b->shrinker, "vmw-balloon"); if (r == 0) b->shrinker_registered = true; diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index b9737da6c4dd..cba57b1f382f 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -875,7 +875,7 @@ static int virtio_balloon_register_shrinker(struct virtio_balloon *vb) vb->shrinker.count_objects = virtio_balloon_shrinker_count; vb->shrinker.seeks = DEFAULT_SEEKS; - return register_shrinker(&vb->shrinker); + return register_shrinker(&vb->shrinker, "virtio-balloon"); } static int virtballoon_probe(struct virtio_device *vdev) diff --git a/drivers/xen/xenbus/xenbus_probe_backend.c b/drivers/xen/xenbus/xenbus_probe_backend.c index 5abded97e1a7..9c09f89d8278 100644 --- a/drivers/xen/xenbus/xenbus_probe_backend.c +++ b/drivers/xen/xenbus/xenbus_probe_backend.c @@ -305,7 +305,7 @@ static int __init xenbus_probe_backend_init(void) register_xenstore_notifier(&xenstore_notifier); - if (register_shrinker(&backend_memory_shrinker)) + if (register_shrinker(&backend_memory_shrinker, "xen-backend")) pr_warn("shrinker registration failed\n"); return 0; diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 6627dd7875ee..eee3e96d877f 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1815,6 +1815,8 @@ static struct dentry *btrfs_mount_root(struct file_system_type *fs_type, error = -EBUSY; } else { snprintf(s->s_id, sizeof(s->s_id), "%pg", bdev); + shrinker_debugfs_rename(&s->s_shrink, "sb-%s:%s", fs_type->name, + s->s_id); btrfs_sb(s)->bdev_holder = fs_type; if (!strstr(crc32c_impl(), "generic")) set_bit(BTRFS_FS_CSUM_IMPL_FAST, &fs_info->flags); diff --git a/fs/erofs/utils.c b/fs/erofs/utils.c index ec9a1d780dc1..46627cb69abe 100644 --- a/fs/erofs/utils.c +++ b/fs/erofs/utils.c @@ -282,7 +282,7 @@ static struct shrinker erofs_shrinker_info = { int __init erofs_init_shrinker(void) { - return register_shrinker(&erofs_shrinker_info); + return register_shrinker(&erofs_shrinker_info, "erofs-shrinker"); } void erofs_exit_shrinker(void) diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c index 9a3a8996aacf..23167efda95e 100644 --- a/fs/ext4/extents_status.c +++ b/fs/ext4/extents_status.c @@ -1654,7 +1654,8 @@ int ext4_es_register_shrinker(struct ext4_sb_info *sbi) sbi->s_es_shrinker.scan_objects = ext4_es_scan; sbi->s_es_shrinker.count_objects = ext4_es_count; sbi->s_es_shrinker.seeks = DEFAULT_SEEKS; - err = register_shrinker(&sbi->s_es_shrinker); + err = register_shrinker(&sbi->s_es_shrinker, "ext4-es:%s", + sbi->s_sb->s_id); if (err) goto err4; diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 37221e94e5ef..bce02306f7a0 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -4579,7 +4579,7 @@ static int __init init_f2fs_fs(void) err = f2fs_init_sysfs(); if (err) goto free_garbage_collection_cache; - err = register_shrinker(&f2fs_shrinker_info); + err = register_shrinker(&f2fs_shrinker_info, "f2fs-shrinker"); if (err) goto free_sysfs; err = register_filesystem(&f2fs_fs_type); diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index c992d53013d3..dca842379cab 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -2533,7 +2533,7 @@ int __init gfs2_glock_init(void) return -ENOMEM; } - ret = register_shrinker(&glock_shrinker); + ret = register_shrinker(&glock_shrinker, "gfs2-glock"); if (ret) { destroy_workqueue(gfs2_delete_workqueue); destroy_workqueue(glock_workqueue); diff --git a/fs/gfs2/main.c b/fs/gfs2/main.c index 244187e3e70f..b66a3e1ec152 100644 --- a/fs/gfs2/main.c +++ b/fs/gfs2/main.c @@ -148,7 +148,7 @@ static int __init init_gfs2_fs(void) if (!gfs2_trans_cachep) goto fail_cachep8; - error = register_shrinker(&gfs2_qd_shrinker); + error = register_shrinker(&gfs2_qd_shrinker, "gfs2-qd"); if (error) goto fail_shrinker; diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index c0cbeeaec2d1..45e4655c8033 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -1418,7 +1418,8 @@ static journal_t *journal_init_common(struct block_device *bdev, if (percpu_counter_init(&journal->j_checkpoint_jh_count, 0, GFP_KERNEL)) goto err_cleanup; - if (register_shrinker(&journal->j_shrinker)) { + if (register_shrinker(&journal->j_shrinker, "jbd2-journal:(%u:%u)", + MAJOR(bdev->bd_dev), MINOR(bdev->bd_dev))) { percpu_counter_destroy(&journal->j_checkpoint_jh_count); goto err_cleanup; } diff --git a/fs/mbcache.c b/fs/mbcache.c index 97c54d3a2227..0b833da0a9a5 100644 --- a/fs/mbcache.c +++ b/fs/mbcache.c @@ -367,7 +367,7 @@ struct mb_cache *mb_cache_create(int bucket_bits) cache->c_shrink.count_objects = mb_cache_count; cache->c_shrink.scan_objects = mb_cache_scan; cache->c_shrink.seeks = DEFAULT_SEEKS; - if (register_shrinker(&cache->c_shrink)) { + if (register_shrinker(&cache->c_shrink, "mbcache-shrinker")) { kfree(cache->c_hash); kfree(cache); goto err_out; diff --git a/fs/nfs/nfs42xattr.c b/fs/nfs/nfs42xattr.c index e7b34f7e0614..a9bf09fdf2c3 100644 --- a/fs/nfs/nfs42xattr.c +++ b/fs/nfs/nfs42xattr.c @@ -1017,15 +1017,16 @@ int __init nfs4_xattr_cache_init(void) if (ret) goto out2; - ret = register_shrinker(&nfs4_xattr_cache_shrinker); + ret = register_shrinker(&nfs4_xattr_cache_shrinker, "nfs-xattr_cache"); if (ret) goto out1; - ret = register_shrinker(&nfs4_xattr_entry_shrinker); + ret = register_shrinker(&nfs4_xattr_entry_shrinker, "nfs-xattr_entry"); if (ret) goto out; - ret = register_shrinker(&nfs4_xattr_large_entry_shrinker); + ret = register_shrinker(&nfs4_xattr_large_entry_shrinker, + "nfs-xattr_large_entry"); if (!ret) return 0; diff --git a/fs/nfs/super.c b/fs/nfs/super.c index 6ab5eeb000dc..82944e14fcea 100644 --- a/fs/nfs/super.c +++ b/fs/nfs/super.c @@ -149,7 +149,7 @@ int __init register_nfs_fs(void) ret = nfs_register_sysctl(); if (ret < 0) goto error_2; - ret = register_shrinker(&acl_shrinker); + ret = register_shrinker(&acl_shrinker, "nfs-acl"); if (ret < 0) goto error_3; #ifdef CONFIG_NFS_V4_2 diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c index 9cb2d590c036..a605c0e39b09 100644 --- a/fs/nfsd/filecache.c +++ b/fs/nfsd/filecache.c @@ -670,7 +670,7 @@ nfsd_file_cache_init(void) goto out_err; } - ret = register_shrinker(&nfsd_file_shrinker); + ret = register_shrinker(&nfsd_file_shrinker, "nfsd-filecache"); if (ret) { pr_err("nfsd: failed to register nfsd_file_shrinker: %d\n", ret); goto out_lru; diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c index 7da88bdc0d6c..9b31e1103e7b 100644 --- a/fs/nfsd/nfscache.c +++ b/fs/nfsd/nfscache.c @@ -176,7 +176,8 @@ int nfsd_reply_cache_init(struct nfsd_net *nn) nn->nfsd_reply_cache_shrinker.scan_objects = nfsd_reply_cache_scan; nn->nfsd_reply_cache_shrinker.count_objects = nfsd_reply_cache_count; nn->nfsd_reply_cache_shrinker.seeks = 1; - status = register_shrinker(&nn->nfsd_reply_cache_shrinker); + status = register_shrinker(&nn->nfsd_reply_cache_shrinker, + "nfsd-reply:%s", nn->nfsd_name); if (status) goto out_stats_destroy; diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c index 09d1307959d0..e0b659900e70 100644 --- a/fs/quota/dquot.c +++ b/fs/quota/dquot.c @@ -2995,7 +2995,7 @@ static int __init dquot_init(void) pr_info("VFS: Dquot-cache hash table entries: %ld (order %ld," " %ld bytes)\n", nr_hash, order, (PAGE_SIZE << order)); - if (register_shrinker(&dqcache_shrinker)) + if (register_shrinker(&dqcache_shrinker, "dquota-cache")) panic("Cannot register dquot shrinker"); return 0; diff --git a/fs/super.c b/fs/super.c index 60f57c7bc0a6..4fca6657f442 100644 --- a/fs/super.c +++ b/fs/super.c @@ -265,7 +265,7 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags, s->s_shrink.count_objects = super_cache_count; s->s_shrink.batch = 1024; s->s_shrink.flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE; - if (prealloc_shrinker(&s->s_shrink)) + if (prealloc_shrinker(&s->s_shrink, "sb-%s", type->name)) goto fail; if (list_lru_init_memcg(&s->s_dentry_lru, &s->s_shrink)) goto fail; @@ -1288,6 +1288,8 @@ int get_tree_bdev(struct fs_context *fc, } else { s->s_mode = mode; snprintf(s->s_id, sizeof(s->s_id), "%pg", bdev); + shrinker_debugfs_rename(&s->s_shrink, "sb-%s:%s", + fc->fs_type->name, s->s_id); sb_set_blocksize(s, block_size(bdev)); error = fill_super(s, fc); if (error) { @@ -1363,6 +1365,8 @@ struct dentry *mount_bdev(struct file_system_type *fs_type, } else { s->s_mode = mode; snprintf(s->s_id, sizeof(s->s_id), "%pg", bdev); + shrinker_debugfs_rename(&s->s_shrink, "sb-%s:%s", + fs_type->name, s->s_id); sb_set_blocksize(s, block_size(bdev)); error = fill_super(s, data, flags & SB_SILENT ? 1 : 0); if (error) { diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c index 0978d01b0ea4..d0c9a09988bc 100644 --- a/fs/ubifs/super.c +++ b/fs/ubifs/super.c @@ -2430,7 +2430,7 @@ static int __init ubifs_init(void) if (!ubifs_inode_slab) return -ENOMEM; - err = register_shrinker(&ubifs_shrinker_info); + err = register_shrinker(&ubifs_shrinker_info, "ubifs-slab"); if (err) goto out_slab; diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index bf4e60871068..4aa9c9cf5b6e 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -1986,7 +1986,8 @@ xfs_alloc_buftarg( btp->bt_shrinker.scan_objects = xfs_buftarg_shrink_scan; btp->bt_shrinker.seeks = DEFAULT_SEEKS; btp->bt_shrinker.flags = SHRINKER_NUMA_AWARE; - if (register_shrinker(&btp->bt_shrinker)) + if (register_shrinker(&btp->bt_shrinker, "xfs-buf:%s", + mp->m_super->s_id)) goto error_pcpu; return btp; diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c index 5269354b1b69..a1941c8b8630 100644 --- a/fs/xfs/xfs_icache.c +++ b/fs/xfs/xfs_icache.c @@ -2201,5 +2201,5 @@ xfs_inodegc_register_shrinker( shrink->flags = SHRINKER_NONSLAB; shrink->batch = XFS_INODEGC_SHRINKER_BATCH; - return register_shrinker(shrink); + return register_shrinker(shrink, "xfs-inodegc:%s", mp->m_super->s_id); } diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c index abf08bbf34a9..c31d57453ceb 100644 --- a/fs/xfs/xfs_qm.c +++ b/fs/xfs/xfs_qm.c @@ -677,7 +677,8 @@ xfs_qm_init_quotainfo( qinf->qi_shrinker.seeks = DEFAULT_SEEKS; qinf->qi_shrinker.flags = SHRINKER_NUMA_AWARE; - error = register_shrinker(&qinf->qi_shrinker); + error = register_shrinker(&qinf->qi_shrinker, "xfs-qm:%s", + mp->m_super->s_id); if (error) goto out_free_inos; diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h index 2ced8149c513..08e6054e061f 100644 --- a/include/linux/shrinker.h +++ b/include/linux/shrinker.h @@ -75,6 +75,7 @@ struct shrinker { #endif #ifdef CONFIG_SHRINKER_DEBUG int debugfs_id; + const char *name; struct dentry *debugfs_entry; #endif /* objs pending delete, per node */ @@ -92,9 +93,11 @@ struct shrinker { */ #define SHRINKER_NONSLAB (1 << 3) -extern int prealloc_shrinker(struct shrinker *shrinker); +extern int __printf(2, 3) prealloc_shrinker(struct shrinker *shrinker, + const char *fmt, ...); extern void register_shrinker_prepared(struct shrinker *shrinker); -extern int register_shrinker(struct shrinker *shrinker); +extern int __printf(2, 3) register_shrinker(struct shrinker *shrinker, + const char *fmt, ...); extern void unregister_shrinker(struct shrinker *shrinker); extern void free_prealloced_shrinker(struct shrinker *shrinker); extern void synchronize_shrinkers(void); @@ -102,6 +105,8 @@ extern void synchronize_shrinkers(void); #ifdef CONFIG_SHRINKER_DEBUG extern int shrinker_debugfs_add(struct shrinker *shrinker); extern void shrinker_debugfs_remove(struct shrinker *shrinker); +extern int __printf(2, 3) shrinker_debugfs_rename(struct shrinker *shrinker, + const char *fmt, ...); #else /* CONFIG_SHRINKER_DEBUG */ static inline int shrinker_debugfs_add(struct shrinker *shrinker) { @@ -110,5 +115,10 @@ static inline int shrinker_debugfs_add(struct shrinker *shrinker) static inline void shrinker_debugfs_remove(struct shrinker *shrinker) { } +static inline __printf(2, 3) +int shrinker_debugfs_rename(struct shrinker *shrinker, const char *fmt, ...) +{ + return 0; +} #endif /* CONFIG_SHRINKER_DEBUG */ #endif /* _LINUX_SHRINKER_H */ diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index c25ba442044a..4b3bf6ebb1eb 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4884,7 +4884,7 @@ static void __init kfree_rcu_batch_init(void) INIT_DELAYED_WORK(&krcp->page_cache_work, fill_page_cache_func); krcp->initialized = true; } - if (register_shrinker(&kfree_rcu_shrinker)) + if (register_shrinker(&kfree_rcu_shrinker, "rcu-kfree")) pr_err("Failed to register kfree_rcu() shrinker!\n"); } diff --git a/mm/huge_memory.c b/mm/huge_memory.c index f9b90a8d7dfa..60d742c33de3 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -423,10 +423,10 @@ static int __init hugepage_init(void) if (err) goto err_slab; - err = register_shrinker(&huge_zero_page_shrinker); + err = register_shrinker(&huge_zero_page_shrinker, "thp-zero"); if (err) goto err_hzp_shrinker; - err = register_shrinker(&deferred_split_shrinker); + err = register_shrinker(&deferred_split_shrinker, "thp-deferred_split"); if (err) goto err_split_shrinker; diff --git a/mm/shrinker_debug.c b/mm/shrinker_debug.c index 1a70556bd46c..781ecbd3d608 100644 --- a/mm/shrinker_debug.c +++ b/mm/shrinker_debug.c @@ -102,7 +102,7 @@ DEFINE_SHOW_ATTRIBUTE(shrinker_debugfs_count); int shrinker_debugfs_add(struct shrinker *shrinker) { struct dentry *entry; - char buf[16]; + char buf[128]; int id; lockdep_assert_held(&shrinker_rwsem); @@ -116,7 +116,7 @@ int shrinker_debugfs_add(struct shrinker *shrinker) return id; shrinker->debugfs_id = id; - snprintf(buf, sizeof(buf), "%d", id); + snprintf(buf, sizeof(buf), "%s-%d", shrinker->name, id); /* create debugfs entry */ entry = debugfs_create_dir(buf, shrinker_debugfs_root); @@ -131,10 +131,53 @@ int shrinker_debugfs_add(struct shrinker *shrinker) return 0; } +int shrinker_debugfs_rename(struct shrinker *shrinker, const char *fmt, ...) +{ + struct dentry *entry; + char buf[128]; + const char *new, *old; + va_list ap; + int ret = 0; + + va_start(ap, fmt); + new = kvasprintf_const(GFP_KERNEL, fmt, ap); + va_end(ap); + + if (!new) + return -ENOMEM; + + down_write(&shrinker_rwsem); + + old = shrinker->name; + shrinker->name = new; + + if (shrinker->debugfs_entry) { + snprintf(buf, sizeof(buf), "%s-%d", shrinker->name, + shrinker->debugfs_id); + + entry = debugfs_rename(shrinker_debugfs_root, + shrinker->debugfs_entry, + shrinker_debugfs_root, buf); + if (IS_ERR(entry)) + ret = PTR_ERR(entry); + else + shrinker->debugfs_entry = entry; + } + + up_write(&shrinker_rwsem); + + kfree_const(old); + + return ret; +} +EXPORT_SYMBOL(shrinker_debugfs_rename); + void shrinker_debugfs_remove(struct shrinker *shrinker) { lockdep_assert_held(&shrinker_rwsem); + kfree_const(shrinker->name); + if (!shrinker->debugfs_entry) return; diff --git a/mm/vmscan.c b/mm/vmscan.c index 35dedff79eb4..97ac6c6c026d 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -608,7 +608,7 @@ static unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, /* * Add a shrinker callback to be called from the vm. */ -int prealloc_shrinker(struct shrinker *shrinker) +static int __prealloc_shrinker(struct shrinker *shrinker) { unsigned int size; int err; @@ -632,8 +632,36 @@ int prealloc_shrinker(struct shrinker *shrinker) return 0; } +#ifdef CONFIG_SHRINKER_DEBUG +int prealloc_shrinker(struct shrinker *shrinker, const char *fmt, ...) +{ + va_list ap; + int err; + + va_start(ap, fmt); + shrinker->name = kvasprintf_const(GFP_KERNEL, fmt, ap); + va_end(ap); + if (!shrinker->name) + return -ENOMEM; + + err = __prealloc_shrinker(shrinker); + if (err) + kfree_const(shrinker->name); + + return err; +} +#else +int prealloc_shrinker(struct shrinker *shrinker, const char *fmt, ...) +{ + return __prealloc_shrinker(shrinker); +} +#endif + void free_prealloced_shrinker(struct shrinker *shrinker) { +#ifdef CONFIG_SHRINKER_DEBUG + kfree_const(shrinker->name); +#endif if (shrinker->flags & SHRINKER_MEMCG_AWARE) { down_write(&shrinker_rwsem); unregister_memcg_shrinker(shrinker); @@ -654,15 +682,39 @@ void register_shrinker_prepared(struct shrinker *shrinker) up_write(&shrinker_rwsem); } -int register_shrinker(struct shrinker *shrinker) +static int __register_shrinker(struct shrinker *shrinker) { - int err = prealloc_shrinker(shrinker); + int err = __prealloc_shrinker(shrinker); if (err) return err; register_shrinker_prepared(shrinker); return 0; } + +#ifdef CONFIG_SHRINKER_DEBUG +int register_shrinker(struct shrinker *shrinker, const char *fmt, ...) +{ + va_list ap; + int err; + + va_start(ap, fmt); + shrinker->name = kvasprintf_const(GFP_KERNEL, fmt, ap); + va_end(ap); + if (!shrinker->name) + return -ENOMEM; + + err = __register_shrinker(shrinker); + if (err) + kfree_const(shrinker->name); + return err; +} +#else +int register_shrinker(struct shrinker *shrinker, const char *fmt, ...) +{ + return __register_shrinker(shrinker); +} +#endif EXPORT_SYMBOL(register_shrinker); /* diff --git a/mm/workingset.c b/mm/workingset.c index 592569a8974c..a5e84862fc86 100644 --- a/mm/workingset.c +++ b/mm/workingset.c @@ -625,7 +625,7 @@ static int __init workingset_init(void) pr_info("workingset: timestamp_bits=%d max_order=%d bucket_order=%u\n", timestamp_bits, max_order, bucket_order); - ret = prealloc_shrinker(&workingset_shadow_shrinker); + ret = prealloc_shrinker(&workingset_shadow_shrinker, "mm-shadow"); if (ret) goto err; ret = __list_lru_init(&shadow_nodes, true, &shadow_nodes_key, diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c index 5d5fc04385b8..f24b71568e83 100644 --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -2217,7 +2217,8 @@ static int zs_register_shrinker(struct zs_pool *pool) pool->shrinker.batch = 0; pool->shrinker.seeks = DEFAULT_SEEKS; - return register_shrinker(&pool->shrinker); + return register_shrinker(&pool->shrinker, "mm-zspool:%s", + pool->name); } /** diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c index 682fcd24bf43..04e7b55fe0d9 100644 --- a/net/sunrpc/auth.c +++ b/net/sunrpc/auth.c @@ -874,7 +874,7 @@ int __init rpcauth_init_module(void) err = rpc_init_authunix(); if (err < 0) goto out1; - err = register_shrinker(&rpc_cred_shrinker); + err = register_shrinker(&rpc_cred_shrinker, "sunrpc_cred"); if (err < 0) goto out2; return 0; -- cgit v1.2.3 From bbf535fd6f06b94b9d07ed6f09397a936d4a58d8 Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Tue, 31 May 2022 20:22:27 -0700 Subject: mm: shrinkers: add scan interface for shrinker debugfs Add a scan interface which allows to trigger scanning of a particular shrinker and specify memcg and numa node. It's useful for testing, debugging and profiling of a specific scan_objects() callback. Unlike alternatives (creating a real memory pressure and dropping caches via /proc/sys/vm/drop_caches) this interface allows to interact with only one shrinker at once. Also, if a shrinker is misreporting the number of objects (as some do), it doesn't affect scanning. [roman.gushchin@linux.dev: improve typing, fix arg count checking] Link: https://lkml.kernel.org/r/YpgKttTowT22mKPQ@carbon [akpm@linux-foundation.org: fix arg count checking] Link: https://lkml.kernel.org/r/20220601032227.4076670-7-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin Acked-by: Muchun Song Cc: Christophe JAILLET Cc: Dave Chinner Cc: Hillf Danton Cc: Kent Overstreet Signed-off-by: Andrew Morton --- Documentation/admin-guide/mm/shrinker_debugfs.rst | 39 ++++++++++-- mm/shrinker_debug.c | 74 +++++++++++++++++++++++ 2 files changed, 109 insertions(+), 4 deletions(-) (limited to 'mm/shrinker_debug.c') diff --git a/Documentation/admin-guide/mm/shrinker_debugfs.rst b/Documentation/admin-guide/mm/shrinker_debugfs.rst index 1e0e5bdb8179..3887f0b294fe 100644 --- a/Documentation/admin-guide/mm/shrinker_debugfs.rst +++ b/Documentation/admin-guide/mm/shrinker_debugfs.rst @@ -5,14 +5,16 @@ Shrinker Debugfs Interface ========================== Shrinker debugfs interface provides a visibility into the kernel memory -shrinkers subsystem and allows to get information about individual shrinkers. +shrinkers subsystem and allows to get information about individual shrinkers +and interact with them. For each shrinker registered in the system a directory in **/shrinker/** is created. The directory's name is composed from the shrinker's name and an unique id: e.g. *kfree_rcu-0* or *sb-xfs:vda1-36*. -Each shrinker directory contains the **count** file, which allows to trigger -the *count_objects()* callback for each memcg and numa node (if applicable). +Each shrinker directory contains **count** and **scan** files, which allow to +trigger *count_objects()* and *scan_objects()* callbacks for each memcg and +numa node (if applicable). Usage: ------ @@ -43,7 +45,7 @@ Usage: $ cd sb-btrfs\:vda2-24/ $ ls - count + count scan 3. *Count objects* @@ -102,3 +104,32 @@ Usage: 2877 84 0 293 1 0 735 8 0 + +4. *Scan objects* + + The expected input format:: + + + + For a non-memcg-aware shrinker or on a system with no memory + cgrups **0** should be passed as cgroup id. + :: + + $ cd /sys/kernel/debug/shrinker/ + $ cd sb-btrfs\:vda2-24/ + + $ cat count | head -n 5 + 1 212 0 + 21 97 0 + 55 802 5 + 2367 2 0 + 225 13 0 + + $ echo "55 0 200" > scan + + $ cat count | head -n 5 + 1 212 0 + 21 96 0 + 55 752 5 + 2367 2 0 + 225 13 0 diff --git a/mm/shrinker_debug.c b/mm/shrinker_debug.c index 781ecbd3d608..e5b40c43221d 100644 --- a/mm/shrinker_debug.c +++ b/mm/shrinker_debug.c @@ -99,6 +99,78 @@ static int shrinker_debugfs_count_show(struct seq_file *m, void *v) } DEFINE_SHOW_ATTRIBUTE(shrinker_debugfs_count); +static int shrinker_debugfs_scan_open(struct inode *inode, struct file *file) +{ + file->private_data = inode->i_private; + return nonseekable_open(inode, file); +} + +static ssize_t shrinker_debugfs_scan_write(struct file *file, + const char __user *buf, + size_t size, loff_t *pos) +{ + struct shrinker *shrinker = file->private_data; + unsigned long nr_to_scan = 0, ino, read_len; + struct shrink_control sc = { + .gfp_mask = GFP_KERNEL, + }; + struct mem_cgroup *memcg = NULL; + int nid; + char kbuf[72]; + ssize_t ret; + + read_len = size < (sizeof(kbuf) - 1) ? size : (sizeof(kbuf) - 1); + if (copy_from_user(kbuf, buf, read_len)) + return -EFAULT; + kbuf[read_len] = '\0'; + + if (sscanf(kbuf, "%lu %d %lu", &ino, &nid, &nr_to_scan) != 3) + return -EINVAL; + + if (nid < 0 || nid >= nr_node_ids) + return -EINVAL; + + if (nr_to_scan == 0) + return size; + + if (shrinker->flags & SHRINKER_MEMCG_AWARE) { + memcg = mem_cgroup_get_from_ino(ino); + if (!memcg || IS_ERR(memcg)) + return -ENOENT; + + if (!mem_cgroup_online(memcg)) { + mem_cgroup_put(memcg); + return -ENOENT; + } + } else if (ino != 0) { + return -EINVAL; + } + + ret = down_read_killable(&shrinker_rwsem); + if (ret) { + mem_cgroup_put(memcg); + return ret; + } + + sc.nid = nid; + sc.memcg = memcg; + sc.nr_to_scan = nr_to_scan; + sc.nr_scanned = nr_to_scan; + + shrinker->scan_objects(shrinker, &sc); + + up_read(&shrinker_rwsem); + mem_cgroup_put(memcg); + + return size; +} + +static const struct file_operations shrinker_debugfs_scan_fops = { + .owner = THIS_MODULE, + .open = shrinker_debugfs_scan_open, + .write = shrinker_debugfs_scan_write, +}; + int shrinker_debugfs_add(struct shrinker *shrinker) { struct dentry *entry; @@ -128,6 +200,8 @@ int shrinker_debugfs_add(struct shrinker *shrinker) debugfs_create_file("count", 0220, entry, shrinker, &shrinker_debugfs_count_fops); + debugfs_create_file("scan", 0440, entry, shrinker, + &shrinker_debugfs_scan_fops); return 0; } -- cgit v1.2.3 From 14773bfa70e67f4d4ebd60e60cb6e25e8c84d4c0 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Wed, 20 Jul 2022 23:47:55 +0900 Subject: mm: shrinkers: fix double kfree on shrinker name syzbot is reporting double kfree() at free_prealloced_shrinker() [1], for destroy_unused_super() calls free_prealloced_shrinker() even if prealloc_shrinker() returned an error. Explicitly clear shrinker name when prealloc_shrinker() called kfree(). [roman.gushchin@linux.dev: zero shrinker->name in all cases where shrinker->name is freed] Link: https://lkml.kernel.org/r/YtgteTnQTgyuKUSY@castle Link: https://syzkaller.appspot.com/bug?extid=8b481578352d4637f510 [1] Link: https://lkml.kernel.org/r/ffa62ece-6a42-2644-16cf-0d33ef32c676@I-love.SAKURA.ne.jp Fixes: e33c267ab70de424 ("mm: shrinkers: provide shrinkers with names") Reported-by: syzbot Signed-off-by: Tetsuo Handa Acked-by: Roman Gushchin Signed-off-by: Andrew Morton --- mm/shrinker_debug.c | 1 + mm/vmscan.c | 9 +++++++-- 2 files changed, 8 insertions(+), 2 deletions(-) (limited to 'mm/shrinker_debug.c') diff --git a/mm/shrinker_debug.c b/mm/shrinker_debug.c index e5b40c43221d..b05295bab322 100644 --- a/mm/shrinker_debug.c +++ b/mm/shrinker_debug.c @@ -251,6 +251,7 @@ void shrinker_debugfs_remove(struct shrinker *shrinker) lockdep_assert_held(&shrinker_rwsem); kfree_const(shrinker->name); + shrinker->name = NULL; if (!shrinker->debugfs_entry) return; diff --git a/mm/vmscan.c b/mm/vmscan.c index f58761cea0a0..fbb4108250ee 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -644,8 +644,10 @@ int prealloc_shrinker(struct shrinker *shrinker, const char *fmt, ...) return -ENOMEM; err = __prealloc_shrinker(shrinker); - if (err) + if (err) { kfree_const(shrinker->name); + shrinker->name = NULL; + } return err; } @@ -660,6 +662,7 @@ void free_prealloced_shrinker(struct shrinker *shrinker) { #ifdef CONFIG_SHRINKER_DEBUG kfree_const(shrinker->name); + shrinker->name = NULL; #endif if (shrinker->flags & SHRINKER_MEMCG_AWARE) { down_write(&shrinker_rwsem); @@ -704,8 +707,10 @@ int register_shrinker(struct shrinker *shrinker, const char *fmt, ...) return -ENOMEM; err = __register_shrinker(shrinker); - if (err) + if (err) { kfree_const(shrinker->name); + shrinker->name = NULL; + } return err; } #else -- cgit v1.2.3