linux-kernel - Re: [PATCH v4 12/22] lib/stackdepot: use read/write lock

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Date: Sat, 13 Jan 2024 01:19:36 -0800
From: Andi Kleen <ak@...ux.intel.com>
To: Marco Elver <elver@...gle.com>
Cc: Andrey Konovalov <andreyknvl@...il.com>,
	Oscar Salvador <osalvador@...e.de>, andrey.konovalov@...ux.dev,
	Andrew Morton <akpm@...ux-foundation.org>,
	Alexander Potapenko <glider@...gle.com>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Vlastimil Babka <vbabka@...e.cz>, kasan-dev@...glegroups.com,
	Evgenii Stepanov <eugenis@...gle.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Andrey Konovalov <andreyknvl@...gle.com>
Subject: Re: [PATCH v4 12/22] lib/stackdepot: use read/write lock

On Sat, Jan 13, 2024 at 10:12:21AM +0100, Marco Elver wrote:
> On Sat, 13 Jan 2024 at 02:24, Andi Kleen <ak@...ux.intel.com> wrote:
> >
> > On Fri, Jan 12, 2024 at 11:15:05PM +0100, Marco Elver wrote:
> > > +             /*
> > > +              * Stack traces of size 0 are never saved, and we can simply use
> > > +              * the size field as an indicator if this is a new unused stack
> > > +              * record in the freelist.
> > > +              */
> > > +             stack->size = 0;
> >
> > I would use WRITE_ONCE here too, at least for TSan.
> 
> This is written with the pool_lock held.

..which doesn't help because the readers don't take it?

-Andi