linux-kernel - Re: [PATCH RESEND v3 09/10] mm/vma: update vma_assert

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1d360d08-aceb-4d0e-81ce-4544215603f6@suse.cz>
Date: Fri, 23 Jan 2026 17:55:58 +0100
From: Vlastimil Babka <vbabka@...e.cz>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: David Hildenbrand <david@...nel.org>,
 "Liam R . Howlett" <Liam.Howlett@...cle.com>, Mike Rapoport
 <rppt@...nel.org>, Suren Baghdasaryan <surenb@...gle.com>,
 Michal Hocko <mhocko@...e.com>, Shakeel Butt <shakeel.butt@...ux.dev>,
 Jann Horn <jannh@...gle.com>, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, linux-rt-devel@...ts.linux.dev,
 Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
 Will Deacon <will@...nel.org>, Boqun Feng <boqun.feng@...il.com>,
 Waiman Long <longman@...hat.com>,
 Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
 Clark Williams <clrkwllms@...nel.org>, Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH RESEND v3 09/10] mm/vma: update vma_assert_locked() to use
 lockdep

On 1/22/26 14:02, Lorenzo Stoakes wrote:
> +/**
> + * vma_assert_locked() - assert that @vma holds either a VMA read or a VMA write
> + * lock and is not detached.
> + * @vma: The VMA to assert.
> + */
>  static inline void vma_assert_locked(struct vm_area_struct *vma)
>  {
> -	unsigned int mm_lock_seq;
> +	unsigned int refs;
> 
>  	/*
>  	 * See the comment describing the vm_area_struct->vm_refcnt field for
>  	 * details of possible refcnt values.
>  	 */
> -	VM_BUG_ON_VMA(refcount_read(&vma->vm_refcnt) <= 1 &&
> -		      !__is_vma_write_locked(vma, &mm_lock_seq), vma);
> +
> +	/*
> +	 * If read-locked or currently excluding readers, then the VMA is
> +	 * locked.
> +	 */
> +#ifdef CONFIG_LOCKDEP
> +	if (lock_is_held(&vma->vmlock_dep_map))
> +		return;
> +#endif
> +
> +	refs = refcount_read(&vma->vm_refcnt);
> +
> +	/*
> +	 * In this case we're either read-locked, write-locked with temporary
> +	 * readers, or in the midst of excluding readers, all of which means
> +	 * we're locked.
> +	 */
> +	if (refs > 1)
> +		return;
> +
> +	/* It is a bug for the VMA to be detached here. */
> +	VM_BUG_ON_VMA(!refs, vma);
> +

Yeah previously this function was all VM_BUG_ON() but since that's now
frowned upon, can we not do it anymore?
Seem we do have VM_WARN_ON_ONCE_VMA().

> +	/*
> +	 * OK, the VMA has a reference count of 1 which means it is either
> +	 * unlocked and attached or write-locked, so assert that it is
> +	 * write-locked.
> +	 */
> +	vma_assert_write_locked(vma);
>  }
> 
>  static inline bool vma_is_attached(struct vm_area_struct *vma)
> --
> 2.52.0