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From: "Liam R. Howlett" <Liam.Howlett@oracle.com>
To: Josh Law <hlcj1234567@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Alice Ryhl <aliceryhl@google.com>,
	Andrew Ballance <andrewjballance@gmail.com>,
	Josh Law <objecting@objecting.org>,
	maple-tree@lists.infradead.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] lib/maple_tree: fix always-true condition in mas_erase()
Date: Tue, 31 Mar 2026 23:24:00 -0400	[thread overview]
Message-ID: <lma6r3ah4e6v4sreszmbkrcfrxzu7dvhuuzemtkw63v2e6yyj7@a5sys3xfpzpv> (raw)
In-Reply-To: <20260312184054.23481-2-objecting@objecting.org>

* Josh Law <hlcj1234567@gmail.com> [260312 14:41]:
> The condition (!mas_is_active(mas) || !mas_is_start(mas)) is always
> true because ma_active and ma_start are distinct enum values -- a
> state can never be both simultaneously. This causes mas_erase() to
> unconditionally reset the status to ma_start, discarding a valid
> active walk position.
> 
> Change || to && so the reset only fires when the state is neither
> active nor start, matching the equivalent guard in mas_walk().

This should be a function, then.

With a test case, if possible.

> 
> Signed-off-by: Josh Law <objecting@objecting.org>


> ---
>  lib/maple_tree.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index 87a2ba6468ca..9727dcefbf65 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -5574,7 +5574,7 @@ void *mas_erase(struct ma_state *mas)
>  	unsigned long index = mas->index;
>  	MA_WR_STATE(wr_mas, mas, NULL);
>  
> -	if (!mas_is_active(mas) || !mas_is_start(mas))
> +	if (!mas_is_active(mas) && !mas_is_start(mas))
>  		mas->status = ma_start;
>  
>  write_retry:
> -- 
> 2.34.1
> 


  reply	other threads:[~2026-04-01  3:24 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-12 18:40 [PATCH 1/3] lib/maple_tree: fix potential NULL dereference in mas_pop_node() Josh Law
2026-03-12 18:40 ` [PATCH 2/3] lib/maple_tree: fix always-true condition in mas_erase() Josh Law
2026-04-01  3:24   ` Liam R. Howlett [this message]
2026-03-12 20:45 ` [PATCH 1/3] lib/maple_tree: fix potential NULL dereference in mas_pop_node() Andrew Morton
2026-03-12 20:49   ` Josh Law
2026-03-12 20:56     ` Josh Law
2026-03-12 21:14       ` Josh Law
2026-03-12 23:00     ` Alice Ryhl
2026-03-12 23:22   ` Pedro Falcato
2026-03-13  7:17     ` Josh Law
2026-03-13  9:05       ` Pedro Falcato
2026-03-13 16:11         ` Josh Law

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