Re: [PATCH 1/2] fs/proc/task_mmu: change lock_vma_range() to return error code

[Lorenzo Stoakes <ljs@kernel.org>]

On Fri, Jun 05, 2026 at 06:57:28PM -0700, Suren Baghdasaryan wrote:
> To correctly propagate error code from lock_vma_range(), change it to
> return the error code instead of the boolean. This simplifies error
> propagation code.
>
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>

Logic LGTM, couple nits below, but:

Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>

> ---
>  fs/proc/task_mmu.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index d32408f7cd5e..023422fcee12 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -162,13 +162,13 @@ static void unlock_ctx_vma(struct proc_maps_locking_ctx *lock_ctx)
>  	}
>  }
>
> -static inline bool lock_vma_range(struct seq_file *m,
> -				  struct proc_maps_locking_ctx *lock_ctx)
> +static inline int lock_vma_range(struct seq_file *m,

Could drop the unnecessary inline here while we're here.

> +				 struct proc_maps_locking_ctx *lock_ctx)
>  {
>  	rcu_read_lock();
>  	reset_lock_ctx(lock_ctx);
>
> -	return true;
> +	return 0;
>  }
>
>  static inline void unlock_vma_range(struct proc_maps_locking_ctx *lock_ctx)
> @@ -245,10 +245,10 @@ static inline void unlock_ctx_mm(struct proc_maps_locking_ctx *lock_ctx)
>  	mmap_read_unlock(lock_ctx->mm);
>  }
>
> -static inline bool lock_vma_range(struct seq_file *m,
> +static inline int lock_vma_range(struct seq_file *m,

Same comment as above.

>  				  struct proc_maps_locking_ctx *lock_ctx)
>  {
> -	return lock_ctx_mm(lock_ctx) == 0;
> +	return lock_ctx_mm(lock_ctx);
>  }
>
>  static inline void unlock_vma_range(struct proc_maps_locking_ctx *lock_ctx)
> @@ -311,6 +311,7 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
>  	struct proc_maps_locking_ctx *lock_ctx;
>  	loff_t last_addr = *ppos;
>  	struct mm_struct *mm;
> +	int err;
>
>  	/* See m_next(). Zero at the start or after lseek. */
>  	if (last_addr == SENTINEL_VMA_END)
> @@ -328,11 +329,12 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
>  		return NULL;
>  	}
>
> -	if (!lock_vma_range(m, lock_ctx)) {
> +	err = lock_vma_range(m, lock_ctx);
> +	if (err) {
>  		mmput(mm);
>  		put_task_struct(priv->task);
>  		priv->task = NULL;
> -		return ERR_PTR(-EINTR);
> +		return ERR_PTR(err);
>  	}
>
>  	/*
>
> base-commit: e178a530a81621a29efbca49b3b78202a18236e4
> --
> 2.54.0.1032.g2f8565e1d1-goog
>