linux-kernel - Re: resend----[PATCH] Avoid high order memory allocating with kmalloc, when read large seq file

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Date:	Fri, 01 Feb 2013 11:31:12 +0800
From:	xtu4 <xiaobing.tu@...el.com>
To:	linux-kernel@...r.kernel.org, guifang.tang@...el.com,
	linX.z.chen@...el.com, akpm@...ux-foundation.org,
	yanmin.zhang@...el.com
Subject: Re: resend----[PATCH] Avoid high order memory allocating with kmalloc,
 when read large seq file

On 01/31/2013 02:11 PM, xtu4 wrote:
> [SEQ_FILE] Avoid high order memory allocating with kmalloc
>  when read large seq file
>
> currently, when dumpstate access /proc/xxx/binder , this binder 
> include lots of info,
> it will use seq_read in kernel, in this function, it will trigger high 
> order memory alloc,
> when read binder info or other large file, this will cause memory 
> presure when system
> don't have contious high order memory, it will lead to high kswap 
> workload to reclaim the
> page. so change kmalloc to vmalloc, it can avoid contiously high order 
> memory allocating.
> [ 4356.532357] dumpstate: page allocation failure: order:4, mode:0x40d0
> [ 4356.532400] Pid: 18256, comm: dumpstate Tainted: G         C 
> 3.0.34-141128-g4be7088 #1
> [ 4356.532416] Call Trace:
> [ 4356.532443]  [<c185c836>] ? printk+0x1d/0x1f
> [ 4356.532467]  [<c12cde1f>] warn_alloc_failed+0xbf/0xf0
> [ 4356.532491]  [<c12d0aba>] __alloc_pages_nodemask+0x4ba/0x6a0
> [ 4356.532521]  [<c12d0d1c>] __get_free_pages+0x1c/0x30
> [ 4356.532541]  [<c12f51e1>] kmalloc_order_trace+0x21/0xd0
> [ 4356.532561]  [<c131d0f7>] ? seq_read+0x137/0x390
> [ 4356.532579]  [<c12f549a>] __kmalloc+0x20a/0x230
> [ 4356.532596]  [<c131d0f7>] ? seq_read+0x137/0x390
> [ 4356.532616]  [<c12d343c>] ? put_page+0x2c/0x40
> [ 4356.532634]  [<c12f4a7d>] ? kfree+0xcd/0x160
> [ 4356.532655]  [<c18656cd>] ? mutex_unlock+0xd/0x10
> [ 4356.532675]  [<c131d109>] seq_read+0x149/0x390
> [ 4356.532697]  [<c130062c>] vfs_read+0x8c/0x160
> [ 4356.532716]  [<c131cfc0>] ? seq_lseek+0x180/0x180
> [ 4356.532735]  [<c130073d>] sys_read+0x3d/0x70
> [ 4356.532755]  [<c1866e91>] syscall_call+0x7/0xb
> [ 4356.532777]  [<c1860000>] ? log_dir_items+0x33d/0x40c
>
> the m->size is very huge
> <3>[ 1185.457656, 1] xiaobing >> seq_read: m->size 8192
> <3>[ 1185.463462, 1] xiaobing >> seq_read: m->size 16384
> <3>[ 1185.470472, 1] xiaobing >> seq_read: m->size 32768
> <3>[ 1185.481201, 0] xiaobing >> seq_read: m->size 8192
> <3>[ 1185.488071, 0] xiaobing >> seq_read: m->size 16384
> <3>[ 1185.495892, 0] xiaobing >> seq_read: m->size 32768
> <3>[ 1185.504841, 0] xiaobing >> seq_read: m->size 65536
> <3>[ 1185.517180, 0] xiaobing >> seq_read: m->size 131072
> <3>[ 1185.536286, 0] xiaobing >> seq_read: m->size 262144
>
> some times even more then 262144 byte
>
> Signed-off-by: xiaobing tu <xiaobing.tu@...el.com>
> Change-Id: I892c97d02cf25e59b23c9bc68dff754ea01c1d56
> ---
>  fs/seq_file.c |   22 +++++++++++++++++-----
>  1 files changed, 17 insertions(+), 5 deletions(-)
>
> diff --git a/fs/seq_file.c b/fs/seq_file.c
> index dba43c3..19df826 100644
> --- a/fs/seq_file.c
> +++ b/fs/seq_file.c
> @@ -12,7 +12,7 @@
>
>  #include <asm/uaccess.h>
>  #include <asm/page.h>
> -
> +#include <linux/mm.h>
>  /**
>   *    seq_open -    initialize sequential file
>   *    @file: file we initialize
> @@ -116,7 +116,13 @@ static int traverse(struct seq_file *m, loff_t 
> offset)
>  Eoverflow:
>      m->op->stop(m, p);
>      kfree(m->buf);
> -    m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
> +
> +    is_vmalloc_addr(m->buf) ? vfree(m->buf) : kfree(m->buf);
> +    m->size <<= 1;
> +    if (m->size <= (2 * PAGE_SIZE))
> +        m->buf = kmalloc(m->size, GFP_KERNEL);
> +    else
> +        m->buf = vmalloc(m->size);
>      return !m->buf ? -ENOMEM : -EAGAIN;
>  }
>
> @@ -209,8 +215,14 @@ ssize_t seq_read(struct file *file, char __user 
> *buf, size_t size, loff_t *ppos)
>          if (m->count < m->size)
>              goto Fill;
>          m->op->stop(m, p);
> -        kfree(m->buf);
> -        m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
> +        is_vmalloc_addr(m->buf) ? vfree(m->buf) : kfree(m->buf);
> +        m->size <<= 1;
> +        if (m->size > 2 * PAGE_SIZE)
> +            m->buf = vmalloc(m->size);
> +        else
> +            m->buf = kmalloc(m->size, GFP_KERNEL);
> +
> +
>          if (!m->buf)
>              goto Enomem;
>          m->count = 0;
> @@ -325,7 +337,7 @@ EXPORT_SYMBOL(seq_lseek);
>  int seq_release(struct inode *inode, struct file *file)
>  {
>      struct seq_file *m = file->private_data;
> -    kfree(m->buf);
> +    is_vmalloc_addr(m->buf) ? vfree(m->buf) : kfree(m->buf);
>      kfree(m);
>      return 0;
>  }

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