linux-kernel - Re: [PATCH] mm/kmemleak: Fix percpu memory leak detection failure

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Message-ID: <Z3Pdq9_HSZw_BzR1@arm.com>
Date: Tue, 31 Dec 2024 12:03:55 +0000
From: Catalin Marinas <catalin.marinas@....com>
To: Uros Bizjak <ubizjak@...il.com>
Cc: Guo Weikang <guoweikang.kernel@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/kmemleak: Fix percpu memory leak detection failure

On Fri, Dec 27, 2024 at 11:42:49AM +0100, Uros Bizjak wrote:
> On Fri, Dec 27, 2024 at 11:37 AM Uros Bizjak <ubizjak@...il.com> wrote:
> > On Fri, Dec 27, 2024 at 10:23 AM Guo Weikang
> > <guoweikang.kernel@...il.com> wrote:
> > > kmemleak_alloc_percpu gives an incorrect min_count parameter, causing
> > > percpu memory to be considered a gray object.
> > >
> > > Fixes: 8c8685928910 ("mm/kmemleak: use IS_ERR_PCPU() for pointer in the percpu address space")
> > >
> > > Signed-off-by: Guo Weikang <guoweikang.kernel@...il.com>
> >
> > I don't know how 1 turned to 0, the change was definitely unintended.
> 
> Looking at the original patch at [1], it looks like a mismerge to me.
> 
> [1] https://lore.kernel.org/all/20240818210235.33481-2-ubizjak@gmail.com/T/#u

About the same time we had commit 6c99d4eb7c5e ("kmemleak: enable
tracking for percpu pointers") increasing min_count to 1 but in the
merge this got lost.

-- 
Catalin