[PATCH] exfat: use kvmalloc_array/kvfree instead of kmalloc_array/kfree

[PATCH] exfat: use kvmalloc_array/kvfree instead of kmalloc_array/kfree

[gaoming]

The call stack shown below is a scenario in the Linux 4.19 kernel.
Allocating memory failed where exfat fs use kmalloc_array due 
to system memory fragmentation, while the u-disk was inserted
without recognition.
Devices such as u-disk using the exfat file system are pluggable and may be
insert into the system at any time.
However, long-term running systems cannot guarantee the continuity of 
physical memory. Therefore, it's necessary to address this issue.

Binder:2632_6: page allocation failure: order:4,
mode:0x6040c0(GFP_KERNEL|__GFP_COMP), nodemask=(null)
Call trace:
[242178.097582]  dump_backtrace+0x0/0x4
[242178.097589]  dump_stack+0xf4/0x134
[242178.097598]  warn_alloc+0xd8/0x144
[242178.097603]  __alloc_pages_nodemask+0x1364/0x1384
[242178.097608]  kmalloc_order+0x2c/0x510
[242178.097612]  kmalloc_order_trace+0x40/0x16c
[242178.097618]  __kmalloc+0x360/0x408
[242178.097624]  load_alloc_bitmap+0x160/0x284
[242178.097628]  exfat_fill_super+0xa3c/0xe7c
[242178.097635]  mount_bdev+0x2e8/0x3a0
[242178.097638]  exfat_fs_mount+0x40/0x50
[242178.097643]  mount_fs+0x138/0x2e8
[242178.097649]  vfs_kern_mount+0x90/0x270
[242178.097655]  do_mount+0x798/0x173c
[242178.097659]  ksys_mount+0x114/0x1ac
[242178.097665]  __arm64_sys_mount+0x24/0x34
[242178.097671]  el0_svc_common+0xb8/0x1b8
[242178.097676]  el0_svc_handler+0x74/0x90
[242178.097681]  el0_svc+0x8/0x340

By analyzing the exfat code,we found that continuous physical memory is
not required here,so kvmalloc_array is used can solve this problem.

Signed-off-by: gaoming <gaoming20@hihonor.com>
---
 fs/exfat/balloc.c | 4 ++--
 fs/exfat/dir.c    | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c
index 9f42f25fab92..a183558cb7a0 100644
--- a/fs/exfat/balloc.c
+++ b/fs/exfat/balloc.c
@@ -69,7 +69,7 @@ static int exfat_allocate_bitmap(struct super_block *sb,
 	}
 	sbi->map_sectors = ((need_map_size - 1) >>
 			(sb->s_blocksize_bits)) + 1;
-	sbi->vol_amap = kmalloc_array(sbi->map_sectors,
+	sbi->vol_amap = kvmalloc_array(sbi->map_sectors,
 				sizeof(struct buffer_head *), GFP_KERNEL);
 	if (!sbi->vol_amap)
 		return -ENOMEM;
@@ -84,7 +84,7 @@ static int exfat_allocate_bitmap(struct super_block *sb,
 			while (j < i)
 				brelse(sbi->vol_amap[j++]);
 
-			kfree(sbi->vol_amap);
+			kvfree(sbi->vol_amap);
 			sbi->vol_amap = NULL;
 			return -EIO;
 		}
diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c
index 957574180a5e..5cbb78d0a2a2 100644
--- a/fs/exfat/dir.c
+++ b/fs/exfat/dir.c
@@ -649,7 +649,7 @@ int exfat_put_dentry_set(struct exfat_entry_set_cache *es, int sync)
 			brelse(es->bh[i]);
 
 	if (IS_DYNAMIC_ES(es))
-		kfree(es->bh);
+		kvfree(es->bh);
 
 	return err;
 }
@@ -888,7 +888,7 @@ int exfat_get_dentry_set(struct exfat_entry_set_cache *es,
 
 	num_bh = EXFAT_B_TO_BLK_ROUND_UP(off + num_entries * DENTRY_SIZE, sb);
 	if (num_bh > ARRAY_SIZE(es->__bh)) {
-		es->bh = kmalloc_array(num_bh, sizeof(*es->bh), GFP_KERNEL);
+		es->bh = kvmalloc_array(num_bh, sizeof(*es->bh), GFP_KERNEL);
 		if (!es->bh) {
 			brelse(bh);
 			return -ENOMEM;
-- 
2.17.1

Re: [PATCH] exfat: use kvmalloc_array/kvfree instead of kmalloc_array/kfree

[Namjae Jeon]

2023-07-05 18:15 GMT+09:00, gaoming <gaoming20@hihonor.com>:
> The call stack shown below is a scenario in the Linux 4.19 kernel.
> Allocating memory failed where exfat fs use kmalloc_array due
> to system memory fragmentation, while the u-disk was inserted
> without recognition.
> Devices such as u-disk using the exfat file system are pluggable and may be
> insert into the system at any time.
> However, long-term running systems cannot guarantee the continuity of
> physical memory. Therefore, it's necessary to address this issue.
>
> Binder:2632_6: page allocation failure: order:4,
> mode:0x6040c0(GFP_KERNEL|__GFP_COMP), nodemask=(null)
> Call trace:
> [242178.097582]  dump_backtrace+0x0/0x4
> [242178.097589]  dump_stack+0xf4/0x134
> [242178.097598]  warn_alloc+0xd8/0x144
> [242178.097603]  __alloc_pages_nodemask+0x1364/0x1384
> [242178.097608]  kmalloc_order+0x2c/0x510
> [242178.097612]  kmalloc_order_trace+0x40/0x16c
> [242178.097618]  __kmalloc+0x360/0x408
> [242178.097624]  load_alloc_bitmap+0x160/0x284
> [242178.097628]  exfat_fill_super+0xa3c/0xe7c
> [242178.097635]  mount_bdev+0x2e8/0x3a0
> [242178.097638]  exfat_fs_mount+0x40/0x50
> [242178.097643]  mount_fs+0x138/0x2e8
> [242178.097649]  vfs_kern_mount+0x90/0x270
> [242178.097655]  do_mount+0x798/0x173c
> [242178.097659]  ksys_mount+0x114/0x1ac
> [242178.097665]  __arm64_sys_mount+0x24/0x34
> [242178.097671]  el0_svc_common+0xb8/0x1b8
> [242178.097676]  el0_svc_handler+0x74/0x90
> [242178.097681]  el0_svc+0x8/0x340
>
> By analyzing the exfat code,we found that continuous physical memory is
> not required here,so kvmalloc_array is used can solve this problem.
>
> Signed-off-by: gaoming <gaoming20@hihonor.com>
> ---
>  fs/exfat/balloc.c | 4 ++--
>  fs/exfat/dir.c    | 4 ++--
>  2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c
> index 9f42f25fab92..a183558cb7a0 100644
> --- a/fs/exfat/balloc.c
> +++ b/fs/exfat/balloc.c
> @@ -69,7 +69,7 @@ static int exfat_allocate_bitmap(struct super_block *sb,
>  	}
>  	sbi->map_sectors = ((need_map_size - 1) >>
>  			(sb->s_blocksize_bits)) + 1;
> -	sbi->vol_amap = kmalloc_array(sbi->map_sectors,
> +	sbi->vol_amap = kvmalloc_array(sbi->map_sectors,
>  				sizeof(struct buffer_head *), GFP_KERNEL);
>  	if (!sbi->vol_amap)
>  		return -ENOMEM;
> @@ -84,7 +84,7 @@ static int exfat_allocate_bitmap(struct super_block *sb,
>  			while (j < i)
>  				brelse(sbi->vol_amap[j++]);
>
> -			kfree(sbi->vol_amap);
> +			kvfree(sbi->vol_amap);
>  			sbi->vol_amap = NULL;
>  			return -EIO;
>  		}
> diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c
> index 957574180a5e..5cbb78d0a2a2 100644
> --- a/fs/exfat/dir.c
> +++ b/fs/exfat/dir.c
> @@ -649,7 +649,7 @@ int exfat_put_dentry_set(struct exfat_entry_set_cache
> *es, int sync)
>  			brelse(es->bh[i]);
>
>  	if (IS_DYNAMIC_ES(es))
> -		kfree(es->bh);
> +		kvfree(es->bh);
>
>  	return err;
>  }
> @@ -888,7 +888,7 @@ int exfat_get_dentry_set(struct exfat_entry_set_cache
> *es,
>
>  	num_bh = EXFAT_B_TO_BLK_ROUND_UP(off + num_entries * DENTRY_SIZE, sb);
>  	if (num_bh > ARRAY_SIZE(es->__bh)) {
> -		es->bh = kmalloc_array(num_bh, sizeof(*es->bh), GFP_KERNEL);
> +		es->bh = kvmalloc_array(num_bh, sizeof(*es->bh), GFP_KERNEL);
Could you please elaborate why you change this to kvmalloc_array also?

Thanks.
>  		if (!es->bh) {
>  			brelse(bh);
>  			return -ENOMEM;
> --
> 2.17.1
>
>

答复: [PATCH] exfat: use kvmalloc_array/kvfree instead of kmalloc_array/kfree

[gaoming]

exfat_get_dentry_set could be called after the u-disk have been inserted, 
through exfat_find, __exfat_write_inode functions.
This could happen at any time, which scenario can not guarantee the 
continuity of physical memory.
This bugfix will enhance the robustness of exfat.

Thanks.
-----邮件原件-----
发件人: Namjae Jeon <linkinjeon@kernel.org> 
发送时间: 2023年7月7日 7:10
收件人: gaoming <gaoming20@hihonor.com>
抄送: Sungjong Seo <sj1557.seo@samsung.com>; open list:EXFAT FILE SYSTEM <linux-fsdevel@vger.kernel.org>; open list <linux-kernel@vger.kernel.org>; fengbaopeng <fengbaopeng@hihonor.com>; gaoxu <gaoxu2@hihonor.com>; wangfei 00014658 <wangfei66@hihonor.com>; shenchen 00013118 <harry.shen@hihonor.com>
主题: Re: [PATCH] exfat: use kvmalloc_array/kvfree instead of kmalloc_array/kfree

2023-07-05 18:15 GMT+09:00, gaoming <gaoming20@hihonor.com>:
> The call stack shown below is a scenario in the Linux 4.19 kernel.
> Allocating memory failed where exfat fs use kmalloc_array due to 
> system memory fragmentation, while the u-disk was inserted without 
> recognition.
> Devices such as u-disk using the exfat file system are pluggable and 
> may be insert into the system at any time.
> However, long-term running systems cannot guarantee the continuity of 
> physical memory. Therefore, it's necessary to address this issue.
>
> Binder:2632_6: page allocation failure: order:4, 
> mode:0x6040c0(GFP_KERNEL|__GFP_COMP), nodemask=(null) Call trace:
> [242178.097582]  dump_backtrace+0x0/0x4 [242178.097589]  
> dump_stack+0xf4/0x134 [242178.097598]  warn_alloc+0xd8/0x144 
> [242178.097603]  __alloc_pages_nodemask+0x1364/0x1384
> [242178.097608]  kmalloc_order+0x2c/0x510 [242178.097612]  
> kmalloc_order_trace+0x40/0x16c [242178.097618]  __kmalloc+0x360/0x408 
> [242178.097624]  load_alloc_bitmap+0x160/0x284 [242178.097628]  
> exfat_fill_super+0xa3c/0xe7c [242178.097635]  mount_bdev+0x2e8/0x3a0 
> [242178.097638]  exfat_fs_mount+0x40/0x50 [242178.097643]  
> mount_fs+0x138/0x2e8 [242178.097649]  vfs_kern_mount+0x90/0x270 
> [242178.097655]  do_mount+0x798/0x173c [242178.097659]  
> ksys_mount+0x114/0x1ac [242178.097665]  __arm64_sys_mount+0x24/0x34 
> [242178.097671]  el0_svc_common+0xb8/0x1b8 [242178.097676]  
> el0_svc_handler+0x74/0x90 [242178.097681]  el0_svc+0x8/0x340
>
> By analyzing the exfat code,we found that continuous physical memory 
> is not required here,so kvmalloc_array is used can solve this problem.
>
> Signed-off-by: gaoming <gaoming20@hihonor.com>
> ---
>  fs/exfat/balloc.c | 4 ++--
>  fs/exfat/dir.c    | 4 ++--
>  2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c index 
> 9f42f25fab92..a183558cb7a0 100644
> --- a/fs/exfat/balloc.c
> +++ b/fs/exfat/balloc.c
> @@ -69,7 +69,7 @@ static int exfat_allocate_bitmap(struct super_block *sb,
>  	}
>  	sbi->map_sectors = ((need_map_size - 1) >>
>  			(sb->s_blocksize_bits)) + 1;
> -	sbi->vol_amap = kmalloc_array(sbi->map_sectors,
> +	sbi->vol_amap = kvmalloc_array(sbi->map_sectors,
>  				sizeof(struct buffer_head *), GFP_KERNEL);
>  	if (!sbi->vol_amap)
>  		return -ENOMEM;
> @@ -84,7 +84,7 @@ static int exfat_allocate_bitmap(struct super_block *sb,
>  			while (j < i)
>  				brelse(sbi->vol_amap[j++]);
>
> -			kfree(sbi->vol_amap);
> +			kvfree(sbi->vol_amap);
>  			sbi->vol_amap = NULL;
>  			return -EIO;
>  		}
> diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c index 
> 957574180a5e..5cbb78d0a2a2 100644
> --- a/fs/exfat/dir.c
> +++ b/fs/exfat/dir.c
> @@ -649,7 +649,7 @@ int exfat_put_dentry_set(struct 
> exfat_entry_set_cache *es, int sync)
>  			brelse(es->bh[i]);
>
>  	if (IS_DYNAMIC_ES(es))
> -		kfree(es->bh);
> +		kvfree(es->bh);
>
>  	return err;
>  }
> @@ -888,7 +888,7 @@ int exfat_get_dentry_set(struct 
> exfat_entry_set_cache *es,
>
>  	num_bh = EXFAT_B_TO_BLK_ROUND_UP(off + num_entries * DENTRY_SIZE, sb);
>  	if (num_bh > ARRAY_SIZE(es->__bh)) {
> -		es->bh = kmalloc_array(num_bh, sizeof(*es->bh), GFP_KERNEL);
> +		es->bh = kvmalloc_array(num_bh, sizeof(*es->bh), GFP_KERNEL);
Could you please elaborate why you change this to kvmalloc_array also?

Thanks.
>  		if (!es->bh) {
>  			brelse(bh);
>  			return -ENOMEM;
> --
> 2.17.1
>
>

Re: 答复: [PATCH] exfat: use kvmalloc_array/kvfree instead of kmalloc_array/kfree

[Namjae Jeon]

2023-07-07 11:27 GMT+09:00, gaoming <gaoming20@hihonor.com>:
> exfat_get_dentry_set could be called after the u-disk have been inserted,
> through exfat_find, __exfat_write_inode functions.
> This could happen at any time, which scenario can not guarantee the
> continuity of physical memory.
> This bugfix will enhance the robustness of exfat.
I'm sorry, but I understood that it was changed even though you didn't
find any particular problem. I think there will not be issues like
allocation-bitmap allocation failures. I will delete this code and
apply it. If you don't agree, please explain how much memory is
allocated here.
Thanks.
>
> Thanks.
> -----邮件原件-----
> 发件人: Namjae Jeon <linkinjeon@kernel.org>
> 发送时间: 2023年7月7日 7:10
> 收件人: gaoming <gaoming20@hihonor.com>
> 抄送: Sungjong Seo <sj1557.seo@samsung.com>; open list:EXFAT FILE SYSTEM
> <linux-fsdevel@vger.kernel.org>; open list <linux-kernel@vger.kernel.org>;
> fengbaopeng <fengbaopeng@hihonor.com>; gaoxu <gaoxu2@hihonor.com>; wangfei
> 00014658 <wangfei66@hihonor.com>; shenchen 00013118
> <harry.shen@hihonor.com>
> 主题: Re: [PATCH] exfat: use kvmalloc_array/kvfree instead of
> kmalloc_array/kfree
>
> 2023-07-05 18:15 GMT+09:00, gaoming <gaoming20@hihonor.com>:
>> The call stack shown below is a scenario in the Linux 4.19 kernel.
>> Allocating memory failed where exfat fs use kmalloc_array due to
>> system memory fragmentation, while the u-disk was inserted without
>> recognition.
>> Devices such as u-disk using the exfat file system are pluggable and
>> may be insert into the system at any time.
>> However, long-term running systems cannot guarantee the continuity of
>> physical memory. Therefore, it's necessary to address this issue.
>>
>> Binder:2632_6: page allocation failure: order:4,
>> mode:0x6040c0(GFP_KERNEL|__GFP_COMP), nodemask=(null) Call trace:
>> [242178.097582]  dump_backtrace+0x0/0x4 [242178.097589]
>> dump_stack+0xf4/0x134 [242178.097598]  warn_alloc+0xd8/0x144
>> [242178.097603]  __alloc_pages_nodemask+0x1364/0x1384
>> [242178.097608]  kmalloc_order+0x2c/0x510 [242178.097612]
>> kmalloc_order_trace+0x40/0x16c [242178.097618]  __kmalloc+0x360/0x408
>> [242178.097624]  load_alloc_bitmap+0x160/0x284 [242178.097628]
>> exfat_fill_super+0xa3c/0xe7c [242178.097635]  mount_bdev+0x2e8/0x3a0
>> [242178.097638]  exfat_fs_mount+0x40/0x50 [242178.097643]
>> mount_fs+0x138/0x2e8 [242178.097649]  vfs_kern_mount+0x90/0x270
>> [242178.097655]  do_mount+0x798/0x173c [242178.097659]
>> ksys_mount+0x114/0x1ac [242178.097665]  __arm64_sys_mount+0x24/0x34
>> [242178.097671]  el0_svc_common+0xb8/0x1b8 [242178.097676]
>> el0_svc_handler+0x74/0x90 [242178.097681]  el0_svc+0x8/0x340
>>
>> By analyzing the exfat code,we found that continuous physical memory
>> is not required here,so kvmalloc_array is used can solve this problem.
>>
>> Signed-off-by: gaoming <gaoming20@hihonor.com>
>> ---
>>  fs/exfat/balloc.c | 4 ++--
>>  fs/exfat/dir.c    | 4 ++--
>>  2 files changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c index
>> 9f42f25fab92..a183558cb7a0 100644
>> --- a/fs/exfat/balloc.c
>> +++ b/fs/exfat/balloc.c
>> @@ -69,7 +69,7 @@ static int exfat_allocate_bitmap(struct super_block
>> *sb,
>>  	}
>>  	sbi->map_sectors = ((need_map_size - 1) >>
>>  			(sb->s_blocksize_bits)) + 1;
>> -	sbi->vol_amap = kmalloc_array(sbi->map_sectors,
>> +	sbi->vol_amap = kvmalloc_array(sbi->map_sectors,
>>  				sizeof(struct buffer_head *), GFP_KERNEL);
>>  	if (!sbi->vol_amap)
>>  		return -ENOMEM;
>> @@ -84,7 +84,7 @@ static int exfat_allocate_bitmap(struct super_block
>> *sb,
>>  			while (j < i)
>>  				brelse(sbi->vol_amap[j++]);
>>
>> -			kfree(sbi->vol_amap);
>> +			kvfree(sbi->vol_amap);
>>  			sbi->vol_amap = NULL;
>>  			return -EIO;
>>  		}
>> diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c index
>> 957574180a5e..5cbb78d0a2a2 100644
>> --- a/fs/exfat/dir.c
>> +++ b/fs/exfat/dir.c
>> @@ -649,7 +649,7 @@ int exfat_put_dentry_set(struct
>> exfat_entry_set_cache *es, int sync)
>>  			brelse(es->bh[i]);
>>
>>  	if (IS_DYNAMIC_ES(es))
>> -		kfree(es->bh);
>> +		kvfree(es->bh);
>>
>>  	return err;
>>  }
>> @@ -888,7 +888,7 @@ int exfat_get_dentry_set(struct
>> exfat_entry_set_cache *es,
>>
>>  	num_bh = EXFAT_B_TO_BLK_ROUND_UP(off + num_entries * DENTRY_SIZE, sb);
>>  	if (num_bh > ARRAY_SIZE(es->__bh)) {
>> -		es->bh = kmalloc_array(num_bh, sizeof(*es->bh), GFP_KERNEL);
>> +		es->bh = kvmalloc_array(num_bh, sizeof(*es->bh), GFP_KERNEL);
> Could you please elaborate why you change this to kvmalloc_array also?
>
> Thanks.
>>  		if (!es->bh) {
>>  			brelse(bh);
>>  			return -ENOMEM;
>> --
>> 2.17.1
>>
>>
>

答复: 答复: [PATCH] exfat: use kvmalloc_array/kvfree instead of kmalloc_array/kfree

[gaoming]

Ok. Just delete exfat_get_dentry_set modification.
We have checked the mem allocation size really not exceeds one page.

Thanks.

-----邮件原件-----
发件人: Namjae Jeon <linkinjeon@kernel.org> 
发送时间: 2023年7月7日 11:46
收件人: gaoming <gaoming20@hihonor.com>
抄送: Sungjong Seo <sj1557.seo@samsung.com>; open list:EXFAT FILE SYSTEM <linux-fsdevel@vger.kernel.org>; open list <linux-kernel@vger.kernel.org>; fengbaopeng <fengbaopeng@hihonor.com>; gaoxu <gaoxu2@hihonor.com>; wangfei 00014658 <wangfei66@hihonor.com>; shenchen 00013118 <harry.shen@hihonor.com>
主题: Re: 答复: [PATCH] exfat: use kvmalloc_array/kvfree instead of kmalloc_array/kfree

2023-07-07 11:27 GMT+09:00, gaoming <gaoming20@hihonor.com>:
> exfat_get_dentry_set could be called after the u-disk have been 
> inserted, through exfat_find, __exfat_write_inode functions.
> This could happen at any time, which scenario can not guarantee the 
> continuity of physical memory.
> This bugfix will enhance the robustness of exfat.
I'm sorry, but I understood that it was changed even though you didn't find any particular problem. I think there will not be issues like allocation-bitmap allocation failures. I will delete this code and apply it. If you don't agree, please explain how much memory is allocated here.
Thanks.
>
> Thanks.
> -----邮件原件-----
> 发件人: Namjae Jeon <linkinjeon@kernel.org>
> 发送时间: 2023年7月7日 7:10
> 收件人: gaoming <gaoming20@hihonor.com>
> 抄送: Sungjong Seo <sj1557.seo@samsung.com>; open list:EXFAT FILE SYSTEM 
> <linux-fsdevel@vger.kernel.org>; open list 
> <linux-kernel@vger.kernel.org>; fengbaopeng <fengbaopeng@hihonor.com>; 
> gaoxu <gaoxu2@hihonor.com>; wangfei
> 00014658 <wangfei66@hihonor.com>; shenchen 00013118 
> <harry.shen@hihonor.com>
> 主题: Re: [PATCH] exfat: use kvmalloc_array/kvfree instead of 
> kmalloc_array/kfree
>
> 2023-07-05 18:15 GMT+09:00, gaoming <gaoming20@hihonor.com>:
>> The call stack shown below is a scenario in the Linux 4.19 kernel.
>> Allocating memory failed where exfat fs use kmalloc_array due to 
>> system memory fragmentation, while the u-disk was inserted without 
>> recognition.
>> Devices such as u-disk using the exfat file system are pluggable and 
>> may be insert into the system at any time.
>> However, long-term running systems cannot guarantee the continuity of 
>> physical memory. Therefore, it's necessary to address this issue.
>>
>> Binder:2632_6: page allocation failure: order:4, 
>> mode:0x6040c0(GFP_KERNEL|__GFP_COMP), nodemask=(null) Call trace:
>> [242178.097582]  dump_backtrace+0x0/0x4 [242178.097589]
>> dump_stack+0xf4/0x134 [242178.097598]  warn_alloc+0xd8/0x144 
>> [242178.097603]  __alloc_pages_nodemask+0x1364/0x1384
>> [242178.097608]  kmalloc_order+0x2c/0x510 [242178.097612] 
>> kmalloc_order_trace+0x40/0x16c [242178.097618]  __kmalloc+0x360/0x408 
>> [242178.097624]  load_alloc_bitmap+0x160/0x284 [242178.097628] 
>> exfat_fill_super+0xa3c/0xe7c [242178.097635]  mount_bdev+0x2e8/0x3a0 
>> [242178.097638]  exfat_fs_mount+0x40/0x50 [242178.097643]
>> mount_fs+0x138/0x2e8 [242178.097649]  vfs_kern_mount+0x90/0x270 
>> [242178.097655]  do_mount+0x798/0x173c [242178.097659] 
>> ksys_mount+0x114/0x1ac [242178.097665]  __arm64_sys_mount+0x24/0x34 
>> [242178.097671]  el0_svc_common+0xb8/0x1b8 [242178.097676]
>> el0_svc_handler+0x74/0x90 [242178.097681]  el0_svc+0x8/0x340
>>
>> By analyzing the exfat code,we found that continuous physical memory 
>> is not required here,so kvmalloc_array is used can solve this problem.
>>
>> Signed-off-by: gaoming <gaoming20@hihonor.com>
>> ---
>>  fs/exfat/balloc.c | 4 ++--
>>  fs/exfat/dir.c    | 4 ++--
>>  2 files changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c index
>> 9f42f25fab92..a183558cb7a0 100644
>> --- a/fs/exfat/balloc.c
>> +++ b/fs/exfat/balloc.c
>> @@ -69,7 +69,7 @@ static int exfat_allocate_bitmap(struct super_block 
>> *sb,
>>  	}
>>  	sbi->map_sectors = ((need_map_size - 1) >>
>>  			(sb->s_blocksize_bits)) + 1;
>> -	sbi->vol_amap = kmalloc_array(sbi->map_sectors,
>> +	sbi->vol_amap = kvmalloc_array(sbi->map_sectors,
>>  				sizeof(struct buffer_head *), GFP_KERNEL);
>>  	if (!sbi->vol_amap)
>>  		return -ENOMEM;
>> @@ -84,7 +84,7 @@ static int exfat_allocate_bitmap(struct super_block 
>> *sb,
>>  			while (j < i)
>>  				brelse(sbi->vol_amap[j++]);
>>
>> -			kfree(sbi->vol_amap);
>> +			kvfree(sbi->vol_amap);
>>  			sbi->vol_amap = NULL;
>>  			return -EIO;
>>  		}
>> diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c index
>> 957574180a5e..5cbb78d0a2a2 100644
>> --- a/fs/exfat/dir.c
>> +++ b/fs/exfat/dir.c
>> @@ -649,7 +649,7 @@ int exfat_put_dentry_set(struct 
>> exfat_entry_set_cache *es, int sync)
>>  			brelse(es->bh[i]);
>>
>>  	if (IS_DYNAMIC_ES(es))
>> -		kfree(es->bh);
>> +		kvfree(es->bh);
>>
>>  	return err;
>>  }
>> @@ -888,7 +888,7 @@ int exfat_get_dentry_set(struct 
>> exfat_entry_set_cache *es,
>>
>>  	num_bh = EXFAT_B_TO_BLK_ROUND_UP(off + num_entries * DENTRY_SIZE, sb);
>>  	if (num_bh > ARRAY_SIZE(es->__bh)) {
>> -		es->bh = kmalloc_array(num_bh, sizeof(*es->bh), GFP_KERNEL);
>> +		es->bh = kvmalloc_array(num_bh, sizeof(*es->bh), GFP_KERNEL);
> Could you please elaborate why you change this to kvmalloc_array also?
>
> Thanks.
>>  		if (!es->bh) {
>>  			brelse(bh);
>>  			return -ENOMEM;
>> --
>> 2.17.1
>>
>>
>