Re: [PATCH v22 07/16] xfs: Handle krealloc errors in xlog_recover_add_to_cont_trans

Allison Henderson
2021-07-30T09:17:49Z

On 7/29/21 1:27 AM, Chandan Babu R wrote:
> On 27 Jul 2021 at 11:50, Allison Henderson wrote:
>> Because xattrs can be over a page in size, we need to handle possible
>> krealloc errors to avoid warnings. If the allocation does fail, fall
>> back to kmem_alloc_large, with a memcpy.
>>
>> The warning:
>> WARNING: CPU: 1 PID: 20255 at mm/page_alloc.c:3446
>> get_page_from_freelist+0x100b/0x1690
>>
>> is caused when sizes larger that a page are allocated with the
>> __GFP_NOFAIL flag option. We encounter this error now because attr
>> values can be up to 64k in size. So we cannot use __GFP_NOFAIL, and
>> we need to handle the error code if the allocation fails.
>>
>
> Looks good to me.
>
> Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Alrighty, thanks!

Allison

>
>> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
>> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
>> ---
>> fs/xfs/xfs_log_recover.c | 10 +++++++++-
>> 1 file changed, 9 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
>> index 12118d5..1212fa1 100644
>> --- a/fs/xfs/xfs_log_recover.c
>> +++ b/fs/xfs/xfs_log_recover.c
>> @@ -2088,7 +2088,15 @@ xlog_recover_add_to_cont_trans(
>> old_ptr = item->ri_buf[item->ri_cnt-1].i_addr;
>> old_len = item->ri_buf[item->ri_cnt-1].i_len;
>>
>> - ptr = krealloc(old_ptr, len + old_len, GFP_KERNEL | __GFP_NOFAIL);
>> + ptr = krealloc(old_ptr, len + old_len, GFP_KERNEL);
>> + if (ptr == NULL) {
>> + ptr = kmem_alloc_large(len + old_len, KM_ZERO);
>> + if (ptr == NULL)
>> + return -ENOMEM;
>> +
>> + memcpy(ptr, old_ptr, old_len);
>> + }
>> +
>> memcpy(&ptr[old_len], dp, len);
>> item->ri_buf[item->ri_cnt-1].i_len += len;
>> item->ri_buf[item->ri_cnt-1].i_addr = ptr;
>
>