Messages in this thread Patch in this message | | | From | Konstantin Khorenko <> | Subject | [PATCH RFC 1/1] kernfs: keep kernfs node alive for __kernfs_remove() | Date | Tue, 16 Apr 2019 18:53:35 +0300 |
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__kernfs_remove() which is called under kernfs_mutex, assumes nobody kills kernfs node whie it's working on it and "get"s current kernfs node for that.
But we hit a warning in kernfs_get(): kn->counter == 0 already: ------------[ cut here ]------------ WARNING: CPU: 2 PID: 63923 at fs/kernfs/dir.c:377 kernfs_get+0x2f/0x40 ... Call Trace: [<ffffffffa7f92e67>] dump_stack+0x19/0x1b [<ffffffffa78987b8>] __warn+0xd8/0x100 [<ffffffffa78988fd>] warn_slowpath_null+0x1d/0x20 [<ffffffffa7aecaff>] kernfs_get+0x2f/0x40 [<ffffffffa7aed233>] __kernfs_remove+0x113/0x260 [<ffffffffa7aee201>] kernfs_remove+0x21/0x30 [<ffffffffa7af1010>] sysfs_remove_dir+0x50/0x80 [<ffffffffa7b9fb38>] kobject_del+0x18/0x50 [<ffffffffa7a38a4d>] sysfs_slab_remove+0x3d/0x50 [<ffffffffa79f1e6b>] do_kmem_cache_release+0x3b/0x70 [<ffffffffa79f2aa1>] memcg_destroy_kmem_caches+0xb1/0xf0 [<ffffffffa7a4ed5c>] mem_cgroup_css_free+0x4c/0x280 [<ffffffffa79377fc>] cgroup_free_fn+0x4c/0x120 [<ffffffffa78bc222>] process_one_work+0x182/0x440 [<ffffffffa78bd3d6>] worker_thread+0x126/0x3c0 [<ffffffffa78c4441>] kthread+0xd1/0xe0
This could be for example because of kernfs_notify_workfn() which does kernfs_put(kn) out of kernfs_mutex held section, so move kernfs_put(kn) under the mutex.
Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com> --- fs/kernfs/file.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c index ae948aaa4c53..ab9c7e2064cc 100644 --- a/fs/kernfs/file.c +++ b/fs/kernfs/file.c @@ -915,8 +915,8 @@ static void kernfs_notify_workfn(struct work_struct *work) iput(inode); } - mutex_unlock(&kernfs_mutex); kernfs_put(kn); + mutex_unlock(&kernfs_mutex); goto repeat; } -- 2.15.1
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