Re: [PATCH] Input: evdev - convert kzalloc()/vzalloc() to kvzalloc()

From: Miles Chen <miles.chen@mediatek.com>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: <linux-input@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-mediatek@lists.infradead.org>, <wsd_upstream@mediatek.com>
Subject: Re: [PATCH] Input: evdev - convert kzalloc()/vzalloc() to kvzalloc()
Date: Thu, 5 Dec 2019 10:22:28 +0800	[thread overview]
Message-ID: <1575512548.12233.5.camel@mtkswgap22> (raw)
In-Reply-To: <20191118054727.31045-1-miles.chen@mediatek.com>

Hi,

Gentle ping.

note:
We can also observe this issue in kernel-4.4, kernel-4.9, and
kernel-4.14.

   Miles

On Mon, 2019-11-18 at 13:47 +0800, Miles Chen wrote:
> We observed a large(order-3) allocation in evdev_open() and it may
> cause an OOM kenrel panic in kzalloc(), before we getting to the
> vzalloc() fallback.
> 
> Fix it by converting kzalloc()/vzalloc() to kvzalloc() to avoid the
> OOM killer logic as we have a vmalloc fallback.
> 
> InputReader invoked oom-killer: gfp_mask=0x240c2c0
> (GFP_KERNEL|__GFP_NOWARN|__GFP_COMP|__GFP_ZERO), nodemask=0, order=3,
> oom_score_adj=-900
> ...
> (dump_backtrace) from (show_stack+0x18/0x1c)
> (show_stack) from (dump_stack+0x94/0xa8)
> (dump_stack) from (dump_header+0x7c/0xe4)
> (dump_header) from (out_of_memory+0x334/0x348)
> (out_of_memory) from (__alloc_pages_nodemask+0xe9c/0xeb8)
> (__alloc_pages_nodemask) from (kmalloc_order_trace+0x34/0x128)
> (kmalloc_order_trace) from (__kmalloc+0x258/0x36c)
> (__kmalloc) from (evdev_open+0x5c/0x17c)
> (evdev_open) from (chrdev_open+0x100/0x204)
> (chrdev_open) from (do_dentry_open+0x21c/0x354)
> (do_dentry_open) from (vfs_open+0x58/0x84)
> (vfs_open) from (path_openat+0x640/0xc98)
> (path_openat) from (do_filp_open+0x78/0x11c)
> (do_filp_open) from (do_sys_open+0x130/0x244)
> (do_sys_open) from (SyS_openat+0x14/0x18)
> (SyS_openat) from (__sys_trace_return+0x0/0x10)
> ...
> Normal: 12488*4kB (UMEH) 6984*8kB (UMEH) 2101*16kB (UMEH) 0*32kB
> 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 139440kB
> HighMem: 206*4kB (H) 131*8kB (H) 42*16kB (H) 2*32kB (H) 0*64kB
> 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 2608kB
> ...
> Kernel panic - not syncing: Out of memory and no killable processes...
> 
> Signed-off-by: Miles Chen <miles.chen@mediatek.com>
> ---
>  drivers/input/evdev.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
> index d7dd6fcf2db0..cf5d7d63fd48 100644
> --- a/drivers/input/evdev.c
> +++ b/drivers/input/evdev.c
> @@ -484,10 +484,7 @@ static int evdev_open(struct inode *inode, struct file *file)
>  	struct evdev_client *client;
>  	int error;
>  
> -	client = kzalloc(struct_size(client, buffer, bufsize),
> -			 GFP_KERNEL | __GFP_NOWARN);
> -	if (!client)
> -		client = vzalloc(struct_size(client, buffer, bufsize));
> +	client = kvzalloc(struct_size(client, buffer, bufsize), GFP_KERNEL);
>  	if (!client)
>  		return -ENOMEM;
>  