linux-kernel - Re: [PATCH 5.15] udf: Allocate name buffer in directory iterator on heap

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Message-ID: <ZzZB9-DX7IWbfSXs@sashalap>
Date: Thu, 14 Nov 2024 13:31:19 -0500
From: Sasha Levin <sashal@...nel.org>
To: Sergey Senozhatsky <senozhatsky@...omium.org>
Cc: stable@...r.kernel.org, linux-kernel@...r.kernel.org,
	Jan Kara <jack@...e.cz>, kernel test robot <lkp@...el.com>
Subject: Re: [PATCH 5.15] udf: Allocate name buffer in directory iterator on
 heap

On Wed, Nov 13, 2024 at 01:30:35PM +0900, Sergey Senozhatsky wrote:
>From: Jan Kara <jack@...e.cz>
>
>[ Upstream commit 0aba4860b0d0216a1a300484ff536171894d49d8 ]
>
>Currently we allocate name buffer in directory iterators (struct
>udf_fileident_iter) on stack. These structures are relatively large
>(some 360 bytes on 64-bit architectures). For udf_rename() which needs
>to keep three of these structures in parallel the stack usage becomes
>rather heavy - 1536 bytes in total. Allocate the name buffer in the
>iterator from heap to avoid excessive stack usage.
>
>Link: https://lore.kernel.org/all/202212200558.lK9x1KW0-lkp@intel.com
>Reported-by: kernel test robot <lkp@...el.com>
>Signed-off-by: Jan Kara <jack@...e.cz>

Your S-O-B is missing, but also it doesn't build:

fs/udf/directory.c: In function 'udf_fiiter_init':
fs/udf/directory.c:251:25: error: implicit declaration of function 'kmalloc'; did you mean 'kvmalloc'? [-Werror=implicit-function-declaration]
   251 |         iter->namebuf = kmalloc(UDF_NAME_LEN_CS0, GFP_KERNEL);
       |                         ^~~~~~~
       |                         kvmalloc
fs/udf/directory.c:251:23: warning: assignment to 'uint8_t *' {aka 'unsigned char *'} from 'int' makes pointer from integer without a cast [-Wint-conversion]
   251 |         iter->namebuf = kmalloc(UDF_NAME_LEN_CS0, GFP_KERNEL);
       |                       ^
fs/udf/directory.c: In function 'udf_fiiter_release':
fs/udf/directory.c:315:9: error: implicit declaration of function 'kfree'; did you mean 'kvfree'? [-Werror=implicit-function-declaration]
   315 |         kfree(iter->namebuf);
       |         ^~~~~
       |         kvfree

-- 
Thanks,
Sasha