linux-kernel - Re: [PATCH RFC] ipmi: use vzalloc instead of kmalloc for user creation

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Date:   Fri, 17 Apr 2020 21:00:06 -0500
From:   Corey Minyard <minyard@....org>
To:     Feng Tang <feng.tang@...el.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        openipmi-developer@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] ipmi: use vzalloc instead of kmalloc for user
 creation

On Fri, Apr 17, 2020 at 01:01:29PM +0800, Feng Tang wrote:
> We met mulitple times of failure of staring bmc-watchdog,
> due to the runtime memory allocation failure of order 4.

I'm beginning to think that using srcu was a bad idea.  It made things
cleaner and easier, but it eats tons of memory.  Sigh.

Applied, at least for a fix for now.

Thanks,

-corey

> 
>      bmc-watchdog: page allocation failure: order:4, mode:0x40cc0(GFP_KERNEL|__GFP_COMP), nodemask=(null),cpuset=/,mems_allowed=0-1
>      CPU: 1 PID: 2571 Comm: bmc-watchdog Not tainted 5.5.0-00045-g7d6bb61d6188c #1
>      Hardware name: Intel Corporation S2600WFT/S2600WFT, BIOS SE5C620.86B.00.01.0015.110720180833 11/07/2018
>      Call Trace:
>       dump_stack+0x66/0x8b
>       warn_alloc+0xfe/0x160
>       __alloc_pages_slowpath+0xd3e/0xd80
>       __alloc_pages_nodemask+0x2f0/0x340
>       kmalloc_order+0x18/0x70
>       kmalloc_order_trace+0x1d/0xb0
>       ipmi_create_user+0x55/0x2c0 [ipmi_msghandler]
>       ipmi_open+0x72/0x110 [ipmi_devintf]
>       chrdev_open+0xcb/0x1e0
>       do_dentry_open+0x1ce/0x380
>       path_openat+0x305/0x14f0
>       do_filp_open+0x9b/0x110
>       do_sys_open+0x1bd/0x250
>       do_syscall_64+0x5b/0x1f0
>       entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> Using vzalloc/vfree for creating ipmi_user heals the
> problem.
> 
> Signed-off-by: Feng Tang <feng.tang@...el.com>
> ---
>  drivers/char/ipmi/ipmi_msghandler.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
> index c48d8f0..96f1573 100644
> --- a/drivers/char/ipmi/ipmi_msghandler.c
> +++ b/drivers/char/ipmi/ipmi_msghandler.c
> @@ -1153,7 +1153,7 @@ static void free_user_work(struct work_struct *work)
>  					      remove_work);
>  
>  	cleanup_srcu_struct(&user->release_barrier);
> -	kfree(user);
> +	vfree(user);
>  }
>  
>  int ipmi_create_user(unsigned int          if_num,
> @@ -1185,7 +1185,7 @@ int ipmi_create_user(unsigned int          if_num,
>  	if (rv)
>  		return rv;
>  
> -	new_user = kmalloc(sizeof(*new_user), GFP_KERNEL);
> +	new_user = vzalloc(sizeof(*new_user));
>  	if (!new_user)
>  		return -ENOMEM;
>  
> @@ -1232,7 +1232,7 @@ int ipmi_create_user(unsigned int          if_num,
>  
>  out_kfree:
>  	srcu_read_unlock(&ipmi_interfaces_srcu, index);
> -	kfree(new_user);
> +	vfree(new_user);
>  	return rv;
>  }
>  EXPORT_SYMBOL(ipmi_create_user);
> -- 
> 2.7.4
>