6.15-stable review patch. If anyone has any objections, please let me know.
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From: Al Viro viro@zeniv.linux.org.uk
commit 3b5260d12b1fe76b566fe182de8abc586b827ed0 upstream.
All versions up to 6.14 did not propagate mount events into detached tree. Shortly after 6.14 a merge of vfs-6.15-rc1.mount.namespace (130e696aa68b) has changed that.
Unfortunately, that has caused userland regressions (reported in https://lore.kernel.org/all/CAOYeF9WQhFDe+BGW=Dp5fK8oRy5AgZ6zokVyTj1Wp4EUiYg...)
Straight revert wouldn't be an option - in particular, the variant in 6.14 had a bug that got fixed in d1ddc6f1d9f0 ("fix IS_MNT_PROPAGATING uses") and we don't want to bring the bug back.
This is a modification of manual revert posted by Christian, with changes needed to avoid reintroducing the breakage in scenario described in d1ddc6f1d9f0.
Cc: stable@vger.kernel.org Reported-by: Allison Karlitskaya lis@redhat.com Tested-by: Allison Karlitskaya lis@redhat.com Acked-by: Christian Brauner brauner@kernel.org Co-developed-by: Christian Brauner brauner@kernel.org Signed-off-by: Al Viro viro@zeniv.linux.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/mount.h | 5 ----- fs/namespace.c | 15 ++------------- fs/pnode.c | 4 ++-- 3 files changed, 4 insertions(+), 20 deletions(-)
--- a/fs/mount.h +++ b/fs/mount.h @@ -7,10 +7,6 @@
extern struct list_head notify_list;
-typedef __u32 __bitwise mntns_flags_t; - -#define MNTNS_PROPAGATING ((__force mntns_flags_t)(1 << 0)) - struct mnt_namespace { struct ns_common ns; struct mount * root; @@ -37,7 +33,6 @@ struct mnt_namespace { struct rb_node mnt_ns_tree_node; /* node in the mnt_ns_tree */ struct list_head mnt_ns_list; /* entry in the sequential list of mounts namespace */ refcount_t passive; /* number references not pinning @mounts */ - mntns_flags_t mntns_flags; } __randomize_layout;
struct mnt_pcp { --- a/fs/namespace.c +++ b/fs/namespace.c @@ -3673,7 +3673,7 @@ static int do_move_mount(struct path *ol if (!(attached ? check_mnt(old) : is_anon_ns(ns))) goto out;
- if (is_anon_ns(ns)) { + if (is_anon_ns(ns) && ns == p->mnt_ns) { /* * Ending up with two files referring to the root of the * same anonymous mount namespace would cause an error @@ -3681,16 +3681,7 @@ static int do_move_mount(struct path *ol * twice into the mount tree which would be rejected * later. But be explicit about it right here. */ - if ((is_anon_ns(p->mnt_ns) && ns == p->mnt_ns)) - goto out; - - /* - * If this is an anonymous mount tree ensure that mount - * propagation can detect mounts that were just - * propagated to the target mount tree so we don't - * propagate onto them. - */ - ns->mntns_flags |= MNTNS_PROPAGATING; + goto out; } else if (is_anon_ns(p->mnt_ns)) { /* * Don't allow moving an attached mount tree to an @@ -3747,8 +3738,6 @@ static int do_move_mount(struct path *ol if (attached) put_mountpoint(old_mp); out: - if (is_anon_ns(ns)) - ns->mntns_flags &= ~MNTNS_PROPAGATING; unlock_mount(mp); if (!err) { if (attached) { --- a/fs/pnode.c +++ b/fs/pnode.c @@ -231,8 +231,8 @@ static int propagate_one(struct mount *m /* skip if mountpoint isn't visible in m */ if (!is_subdir(dest_mp->m_dentry, m->mnt.mnt_root)) return 0; - /* skip if m is in the anon_ns we are emptying */ - if (m->mnt_ns->mntns_flags & MNTNS_PROPAGATING) + /* skip if m is in the anon_ns */ + if (is_anon_ns(m->mnt_ns)) return 0;
if (peers(m, last_dest)) {