On Mon, May 09, 2022 at 11:38:17AM -0700, Roman Gushchin wrote:
> 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.
>
> After this change the shrinker debugfs directory looks like:
> $ cd /sys/kernel/debug/shrinker/
> $ ls
> dqcache-16 sb-hugetlbfs-17 sb-rootfs-2 sb-tmpfs-50
> kfree_rcu-0 sb-hugetlbfs-33 sb-securityfs-6 sb-tracefs-13
> sb-aio-20 sb-iomem-12 sb-selinuxfs-22 sb-xfs:vda1-36
> sb-anon_inodefs-15 sb-mqueue-21 sb-sockfs-8 sb-zsmalloc-19
> sb-bdev-3 sb-nsfs-4 sb-sysfs-26 shadow-18
> sb-bpf-32 sb-pipefs-14 sb-tmpfs-1 thp_deferred_split-10
> sb-btrfs:vda2-24 sb-proc-25 sb-tmpfs-27 thp_zero-9
> sb-cgroup2-30 sb-proc-39 sb-tmpfs-29 xfs_buf-37
> sb-configfs-23 sb-proc-41 sb-tmpfs-35 xfs_inodegc-38
^^^^^^^^^^^^^^
These XFS shrinkers are also per-block device like the superblock.
They need to read like "sb-xfs:vda1-36". and even though it is not
in this list, the xfs dquot shrinker will need this as well.
> sb-dax-11 sb-proc-45 sb-tmpfs-40 zspool-34
> sb-debugfs-7 sb-proc-46 sb-tmpfs-42
> sb-devpts-28 sb-proc-47 sb-tmpfs-43
> sb-devtmpfs-5 sb-pstore-31 sb-tmpfs-44
The proc and tmpfs shrinkers have the same problem - what instance
do they actually refer to?
> diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
> index e1afb9e503e1..5645e92df0c9 100644
> --- a/fs/xfs/xfs_buf.c
> +++ b/fs/xfs/xfs_buf.c
> @@ -1986,7 +1986,7 @@ 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"))
> goto error_pcpu;
> return btp;
>
> diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
> index bffd6eb0b298..d0c4e74ff763 100644
> --- a/fs/xfs/xfs_icache.c
> +++ b/fs/xfs/xfs_icache.c
> @@ -2198,5 +2198,5 @@ xfs_inodegc_register_shrinker(
> shrink->flags = SHRINKER_NONSLAB;
> shrink->batch = XFS_INODEGC_SHRINKER_BATCH;
>
> - return register_shrinker(shrink);
> + return register_shrinker(shrink, "xfs_inodegc");
> }
> diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
> index f165d1a3de1d..93ded9e81f49 100644
> --- a/fs/xfs/xfs_qm.c
> +++ b/fs/xfs/xfs_qm.c
> @@ -686,7 +686,7 @@ 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");
> if (error)
> goto out_free_inos;
Yeah, these all have a xfs_mount passed to them, so the superblock is
easily accessible here (mp->m_super)....
Cheers,
Dave.
--
Dave Chinner
dchinner@xxxxxxxxxx
