Andrei Vagin <avagin@xxxxxxxxxx> writes: > The reason of this optimization is that umount() can hold namespace_sem > for a long time, this semaphore is global, so it affects all users. > Recently Eric W. Biederman added a per mount namespace limit on the > number of mounts. The default number of mounts allowed per mount > namespace at 100,000. Currently this value is allowed to construct a tree > which requires hours to be umounted. I am going to take a hard look at this as this problem sounds very unfortunate. My memory of going through this code before strongly suggests that changing the last list_for_each_entry to list_for_each_entry_reverse is going to impact the correctness of this change. The order of traversal is important if there are several things mounted one on the other that are all being unmounted. Now perhaps your other changes have addressed that but I haven't looked closely enough to see that yet. > @@ -454,7 +473,7 @@ int propagate_umount(struct list_head *list) > list_for_each_entry_reverse(mnt, list, mnt_list) > mark_umount_candidates(mnt); > > - list_for_each_entry(mnt, list, mnt_list) > + list_for_each_entry_reverse(mnt, list, mnt_list) > __propagate_umount(mnt); > return 0; > } Eric -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
