linux-kernel - Re: [PATCH v8 15/16] mm: make vma cache SLAB_TYPESAFE_BY

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Message-ID: <5p3y2umz7yk3ymedybd3vaxz2f6rz52dzcjiihlyvx7aptxri7@yq2scgci3lyc>
Date: Fri, 10 Jan 2025 15:47:28 -0500
From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
To: Suren Baghdasaryan <surenb@...gle.com>
Cc: akpm@...ux-foundation.org, peterz@...radead.org, willy@...radead.org,
        lorenzo.stoakes@...cle.com, mhocko@...e.com, vbabka@...e.cz,
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Subject: Re: [PATCH v8 15/16] mm: make vma cache SLAB_TYPESAFE_BY_RCU

* Suren Baghdasaryan <surenb@...gle.com> [250110 15:35]:
> On Fri, Jan 10, 2025 at 11:46 AM 'Liam R. Howlett' via kernel-team
> 
> >
> >     rwsem_acquire_read(old lock)
> >     __refcount_inc_not_zero_limited() fails
> 
> Are we looking at the same code
> (https://lore.kernel.org/all/20250109023025.2242447-12-surenb@google.com/)?
> The sequence should be reversed here like this:
> 
>      if (!__refcount_inc_not_zero_limited())
>               return false;
>      rwsem_acquire_read(old lock)
> 
> and because __refcount_inc_not_zero_limited() fails,
> rwsem_acquire_read(old lock) should never be called.
> 

We are not, I had an older version of the patch from the 7th.

Sorry for the confusion.

Thanks,
Liam