FAILED: patch "[PATCH] rust: lockdep: Remove support for dynamically allocated" failed to apply to 6.6-stable tree

FAILED: patch "[PATCH] rust: lockdep: Remove support for dynamically allocated" failed to apply to 6.6-stable tree

[gregkh]

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 966944f3711665db13e214fef6d02982c49bb972
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025031632-divorcee-duly-868e@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 966944f3711665db13e214fef6d02982c49bb972 Mon Sep 17 00:00:00 2001
From: Mitchell Levy <levymitchell0@gmail.com>
Date: Fri, 7 Mar 2025 15:27:00 -0800
Subject: [PATCH] rust: lockdep: Remove support for dynamically allocated
 LockClassKeys

Currently, dynamically allocated LockCLassKeys can be used from the Rust
side without having them registered. This is a soundness issue, so
remove them.

Fixes: 6ea5aa08857a ("rust: sync: introduce `LockClassKey`")
Suggested-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Mitchell Levy <levymitchell0@gmail.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250307232717.1759087-11-boqun.feng@gmail.com

diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs
index 3498fb344dc9..16eab9138b2b 100644
--- a/rust/kernel/sync.rs
+++ b/rust/kernel/sync.rs
@@ -30,28 +30,20 @@
 unsafe impl Sync for LockClassKey {}
 
 impl LockClassKey {
-    /// Creates a new lock class key.
-    pub const fn new() -> Self {
-        Self(Opaque::uninit())
-    }
-
     pub(crate) fn as_ptr(&self) -> *mut bindings::lock_class_key {
         self.0.get()
     }
 }
 
-impl Default for LockClassKey {
-    fn default() -> Self {
-        Self::new()
-    }
-}
-
 /// Defines a new static lock class and returns a pointer to it.
 #[doc(hidden)]
 #[macro_export]
 macro_rules! static_lock_class {
     () => {{
-        static CLASS: $crate::sync::LockClassKey = $crate::sync::LockClassKey::new();
+        static CLASS: $crate::sync::LockClassKey =
+            // SAFETY: lockdep expects uninitialized memory when it's handed a statically allocated
+            // lock_class_key
+            unsafe { ::core::mem::MaybeUninit::uninit().assume_init() };
         &CLASS
     }};
 }

Re: FAILED: patch "[PATCH] rust: lockdep: Remove support for dynamically allocated" failed to apply to 6.6-stable tree

[Boqun Feng]

Hi Greg,

On Sun, Mar 16, 2025 at 08:15:32AM +0100, gregkh@linuxfoundation.org wrote:
> 
> The patch below does not apply to the 6.6-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.
> 
> To reproduce the conflict and resubmit, you may use the following commands:
> 
> git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
> git checkout FETCH_HEAD
> git cherry-pick -x 966944f3711665db13e214fef6d02982c49bb972

It's weird because `cherry-pick` works for me:

$ git cherry-pick -x 966944f3711665db13e214fef6d02982c49bb972
Auto-merging rust/kernel/sync.rs
[stable-6.6 f5771e91eac3] rust: lockdep: Remove support for dynamically allocated LockClassKeys
 Author: Mitchell Levy <levymitchell0@gmail.com>
 Date: Fri Mar 7 15:27:00 2025 -0800
 1 file changed, 4 insertions(+), 6 deletions(-)

my base is 594a1dd5138a ("Linux 6.6.83").

I checked the original commit in Linus' tree, it removes the `impl
Default` which doesn't exist in 6.6, however it seems my `cherry-pick`
can realise and fix this! Anyway I will send the fixed patch soon.

Regards,
Boqun

> # <resolve conflicts, build, test, etc.>
> git commit -s
> git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025031632-divorcee-duly-868e@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..
> 
> Possible dependencies:
> 
> 
> 
> thanks,
> 
> greg k-h
> 
> ------------------ original commit in Linus's tree ------------------
> 
> From 966944f3711665db13e214fef6d02982c49bb972 Mon Sep 17 00:00:00 2001
> From: Mitchell Levy <levymitchell0@gmail.com>
> Date: Fri, 7 Mar 2025 15:27:00 -0800
> Subject: [PATCH] rust: lockdep: Remove support for dynamically allocated
>  LockClassKeys
> 
> Currently, dynamically allocated LockCLassKeys can be used from the Rust
> side without having them registered. This is a soundness issue, so
> remove them.
> 
> Fixes: 6ea5aa08857a ("rust: sync: introduce `LockClassKey`")
> Suggested-by: Alice Ryhl <aliceryhl@google.com>
> Signed-off-by: Mitchell Levy <levymitchell0@gmail.com>
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
> Signed-off-by: Ingo Molnar <mingo@kernel.org>
> Reviewed-by: Benno Lossin <benno.lossin@proton.me>
> Cc: stable@vger.kernel.org
> Link: https://lore.kernel.org/r/20250307232717.1759087-11-boqun.feng@gmail.com
> 
> diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs
> index 3498fb344dc9..16eab9138b2b 100644
> --- a/rust/kernel/sync.rs
> +++ b/rust/kernel/sync.rs
> @@ -30,28 +30,20 @@
>  unsafe impl Sync for LockClassKey {}
>  
>  impl LockClassKey {
> -    /// Creates a new lock class key.
> -    pub const fn new() -> Self {
> -        Self(Opaque::uninit())
> -    }
> -
>      pub(crate) fn as_ptr(&self) -> *mut bindings::lock_class_key {
>          self.0.get()
>      }
>  }
>  
> -impl Default for LockClassKey {
> -    fn default() -> Self {
> -        Self::new()
> -    }
> -}
> -
>  /// Defines a new static lock class and returns a pointer to it.
>  #[doc(hidden)]
>  #[macro_export]
>  macro_rules! static_lock_class {
>      () => {{
> -        static CLASS: $crate::sync::LockClassKey = $crate::sync::LockClassKey::new();
> +        static CLASS: $crate::sync::LockClassKey =
> +            // SAFETY: lockdep expects uninitialized memory when it's handed a statically allocated
> +            // lock_class_key
> +            unsafe { ::core::mem::MaybeUninit::uninit().assume_init() };
>          &CLASS
>      }};
>  }
> 

Re: FAILED: patch "[PATCH] rust: lockdep: Remove support for dynamically allocated" failed to apply to 6.6-stable tree

[Greg KH]

On Tue, Mar 18, 2025 at 10:59:58AM -0700, Boqun Feng wrote:
> Hi Greg,
> 
> On Sun, Mar 16, 2025 at 08:15:32AM +0100, gregkh@linuxfoundation.org wrote:
> > 
> > The patch below does not apply to the 6.6-stable tree.
> > If someone wants it applied there, or to any other stable or longterm
> > tree, then please email the backport, including the original git commit
> > id to <stable@vger.kernel.org>.
> > 
> > To reproduce the conflict and resubmit, you may use the following commands:
> > 
> > git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
> > git checkout FETCH_HEAD
> > git cherry-pick -x 966944f3711665db13e214fef6d02982c49bb972
> 
> It's weird because `cherry-pick` works for me:
> 
> $ git cherry-pick -x 966944f3711665db13e214fef6d02982c49bb972
> Auto-merging rust/kernel/sync.rs
> [stable-6.6 f5771e91eac3] rust: lockdep: Remove support for dynamically allocated LockClassKeys
>  Author: Mitchell Levy <levymitchell0@gmail.com>
>  Date: Fri Mar 7 15:27:00 2025 -0800
>  1 file changed, 4 insertions(+), 6 deletions(-)
> 
> my base is 594a1dd5138a ("Linux 6.6.83").
> 
> I checked the original commit in Linus' tree, it removes the `impl
> Default` which doesn't exist in 6.6, however it seems my `cherry-pick`
> can realise and fix this! Anyway I will send the fixed patch soon.

Yeah, git is smart, patch is not:

patching file rust/kernel/sync.rs
Hunk #1 FAILED at 30.
1 out of 1 hunk FAILED -- rejects in file rust/kernel/sync.rs

:(

thanks for the fixup.

greg k-h

[PATCH 6.6.y] rust: lockdep: Remove support for dynamically allocated LockClassKeys

[Boqun Feng]

From: Mitchell Levy <levymitchell0@gmail.com>

Currently, dynamically allocated LockCLassKeys can be used from the Rust
side without having them registered. This is a soundness issue, so
remove them.

Fixes: 6ea5aa08857a ("rust: sync: introduce `LockClassKey`")
Suggested-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Mitchell Levy <levymitchell0@gmail.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250307232717.1759087-11-boqun.feng@gmail.com
(cherry picked from commit 966944f3711665db13e214fef6d02982c49bb972)
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
---
 rust/kernel/sync.rs | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs
index d219ee518eff..8b40589b1028 100644
--- a/rust/kernel/sync.rs
+++ b/rust/kernel/sync.rs
@@ -26,11 +26,6 @@
 unsafe impl Sync for LockClassKey {}
 
 impl LockClassKey {
-    /// Creates a new lock class key.
-    pub const fn new() -> Self {
-        Self(Opaque::uninit())
-    }
-
     pub(crate) fn as_ptr(&self) -> *mut bindings::lock_class_key {
         self.0.get()
     }
@@ -41,7 +36,10 @@ pub(crate) fn as_ptr(&self) -> *mut bindings::lock_class_key {
 #[macro_export]
 macro_rules! static_lock_class {
     () => {{
-        static CLASS: $crate::sync::LockClassKey = $crate::sync::LockClassKey::new();
+        static CLASS: $crate::sync::LockClassKey =
+            // SAFETY: lockdep expects uninitialized memory when it's handed a statically allocated
+            // lock_class_key
+            unsafe { ::core::mem::MaybeUninit::uninit().assume_init() };
         &CLASS
     }};
 }
-- 
2.48.1

Re: [PATCH 6.6.y] rust: lockdep: Remove support for dynamically allocated LockClassKeys

[Sasha Levin]

[ Sasha's backport helper bot ]

Hi,

Summary of potential issues:
⚠️ Found matching upstream commit but patch is missing proper reference to it

Found matching upstream commit: 966944f3711665db13e214fef6d02982c49bb972

WARNING: Author mismatch between patch and found commit:
Backport author: Boqun Feng<boqun.feng@gmail.com>
Commit author: Mitchell Levy<levymitchell0@gmail.com>

Status in newer kernel trees:
6.13.y | Present (different SHA1: 3e5d366aabae)
6.12.y | Present (different SHA1: c5b195dd9564)

Note: The patch differs from the upstream commit:
---
1:  966944f371166 ! 1:  b037a70e0eccb rust: lockdep: Remove support for dynamically allocated LockClassKeys
    @@ Commit message
         Reviewed-by: Benno Lossin <benno.lossin@proton.me>
         Cc: stable@vger.kernel.org
         Link: https://lore.kernel.org/r/20250307232717.1759087-11-boqun.feng@gmail.com
    +    (cherry picked from commit 966944f3711665db13e214fef6d02982c49bb972)
    +    Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
     
      ## rust/kernel/sync.rs ##
     @@
    @@ rust/kernel/sync.rs
          pub(crate) fn as_ptr(&self) -> *mut bindings::lock_class_key {
              self.0.get()
          }
    - }
    - 
    --impl Default for LockClassKey {
    --    fn default() -> Self {
    --        Self::new()
    --    }
    --}
    --
    - /// Defines a new static lock class and returns a pointer to it.
    - #[doc(hidden)]
    +@@ rust/kernel/sync.rs: pub(crate) fn as_ptr(&self) -> *mut bindings::lock_class_key {
      #[macro_export]
      macro_rules! static_lock_class {
          () => {{
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.6.y        |  Success    |  Success   |