linux-kernel - Re: [PATCH v2] ipc/sem: do not sleep with a spin lock held

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Date:   Mon, 3 Jan 2022 10:27:08 +0100
From:   Jiri Slaby <jirislaby@...nel.org>
To:     cgel.zte@...il.com, manfred@...orfullife.com
Cc:     stable@...r.kernel.org, akpm@...ux-foundation.org, arnd@...db.de,
        chi.minghao@....com.cn, dbueso@...e.de,
        linux-kernel@...r.kernel.org, rdunlap@...radead.org,
        shakeelb@...gle.com, unixbhaskar@...il.com, vvs@...tuozzo.com,
        zealci@....com.cn
Subject: Re: [PATCH v2] ipc/sem: do not sleep with a spin lock held

On 23. 12. 21, 4:12, cgel.zte@...il.com wrote:
> From: Minghao Chi <chi.minghao@....com.cn>
> 
> We can't call kvfree() with a spin lock held, so defer it.

Sorry, defer what?

There are attempts to fix kvfree instead, not sure which of these 
approaches (fix kvfree or its callers) won in the end?

> Fixes: fc37a3b8b438 ("[PATCH] ipc sem: use kvmalloc for sem_undo
> allocation")
> 
> Reported-by: Zeal Robot <zealci@....com.cn>
> Signed-off-by: Minghao Chi <chi.minghao@....com.cn>
> ---
> changelog since v2:
> + Fixes: fc37a3b8b438 ("[PATCH] ipc sem: use kvmalloc for sem_undo
> + allocation")
>   ipc/sem.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/ipc/sem.c b/ipc/sem.c
> index 6693daf4fe11..0dbdb98fdf2d 100644
> --- a/ipc/sem.c
> +++ b/ipc/sem.c
> @@ -1964,6 +1964,7 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid)
>   	 */
>   	un = lookup_undo(ulp, semid);
>   	if (un) {
> +		spin_unlock(&ulp->lock);
>   		kvfree(new);
>   		goto success;
>   	}


-- 
js
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